Investigation of Straw and Clay Buildings. Indoor Climate, Energy Consumption and Renovation.

Investigation of Straw and Clay Buildings.

Indoor Climate, Energy Consumption and Renovation.

Study Cases in Crete and Denmark

Rasmus Gonnsen & Laurynas Marcinkus MSc Thesis February 2016

PREFACE We were very fortunate to have Jørn Toftum as supervisor and thank him a lot for seeing the potentials of this thesis and for the trust he showed to us. We would like to express our gratitude to Archanes Project for hosting us for two months and letting us to measure the house (LSC). We thank Myrto (STONE house), Paula (Konkyliehuset) and Lars and Helle (Spunkhuset) for allowing us to measure their houses and for the information they shared with us. Many thanks to Herbert Gruber for the information that he shared and for promoting the questionnaire to ASBN and FASBA accossiations.

Without Bill Christensen, Max Vittrup Jensen, Lars Keller and the strawbale associations it would not be possible to spread the questionnaire so far and collect so many replies. We thank all the participants for filling the questionnaire of 165 questions! We thank Christian Gonnsen, Paul, Yann and Lucilla for translating the questionnaires. Our thanks go to one of the smokiest bars in Copenhagen, “The Moose” allowed us to prepare specimens for the tobacco smoke experiments very well. Special thanks to Giorgos Papadakis, Hilary, Simone, Dimitris, Mathilde, Linards for actively assisting in the correction phase of the report. We thank our co-supervisor Christian Rønne and the professors in ICIEE department who actively supported us, Carsten Røde, Pawel Wargocki and Gabriel Bekö. Many thanks for the generous support to Despoina, Marco, Gaia, Sam, Gabriel, Alina, Mario, Mitsos, Perellas, Ilias, David, Andre, Dushan, Anna, Peter, and many others that may not be remembered right now. Sincere thanks to our parents and families for the unconditional support and the possibility to be here today at all.

Last but not least, Archanes Project is generously offering the SLC house for long-term measurements.

An open collaboration with universities having an interest in the specific technique is offered as well.

A long-term online monitoring can also be a part of a specific investigation.

ABSTRACT An overall understanding of how straw and clay can be used as building materials seems to be a crucial need for the prosperity and wealth of modern societies. Whether structures made of clay and straw comply with local regulations for the energy consumption and indoor climate remains an open question. Straw, a natural waste material being in abundance was examined as a building insulating material. It was found that it can be used in natural buildings, but also to renovate conventional housing. In the study case of this report, only by implementing a wall made of 18cm thick straw reduced 37% the energy consumption and paid back the total amount of the investment in 4.5 years.

Clay, another material that can be found in nature, was examined concerning an element that can regulate indoor climate. It was found that in a cold and humid climate internal clay plaster can successfully regulate the relative humidity keeping it stable in the range of 40-55%. While in warm and humid climate it actively regulated the relative humidity among the spaces of the house (60-75%) within its absorption capacity. A new technique similar to the SLC (Straw Light Clay) was examined and named as Light Straw Clay (LSC). This technique combines a low Îť-value (0,054 W/mK) with a low density (40-50 kg/m3) allowing to save significant amounts of straw. The clay/straw study case houses in Denmark but also in Crete (Greece) were found to perform within the indoor climate ranges suggested by the DS/EN15251. Secondary findings left open issues to criticize the adaptive thermal comfort model, and the air tightness in building envelopes.

Keywords: Straw Bale, Clay Plaster, Light Straw Clay, Energy Simulations, Indoor Climate, Indoor Air Quality, IAQ, Renovation, Questionnaire, Energy Consumption, Stone House, Study Cases, Warm Humid Climate, Cold Humid Climate, Crete, Denmark.

ABBREVIATIONS clo – clothing level CO2e – equivalent carbon dioxide cp - specific heat capacity [J/(kg⋅K)] IAQ – indoor air quality IWEC2 - International Weather for Energy Calculations 2.0 (weather file format) LSC – light straw clay EMC – equilibrium moisture content met – metabolic rate n – air change rate [h-1] PAQ – perceived air quality ppm – parts per million RH – relative humidity [%] R’w – sound reduction index sd - diffusion equivalent air layer thickness [m] SLC – straw light clay u-value – Thermal transmittance [W/(m2*K]

Greek λ- thermal conductivity [W/(m*K)] μ – vapor diffusion coefficient ρ – Density [kg/m2]

CONTENTS 1

Introduction .................................................................................................................................... 1

Objective ................................................................................................................................................. 3 2

Construction materials.................................................................................................................... 4 2.1

2.1.1

What is straw? ................................................................................................................ 4

2.1.2

Embodied energy and CO2 emissions............................................................................. 4

2.1.3

Straw Bales ...................................................................................................................... 6

2.2

3

Clay .......................................................................................................................................... 7

2.2.1

What is clay? ................................................................................................................... 7

2.2.2

Composition tests ........................................................................................................... 8

2.2.3

Facts about loam ............................................................................................................. 8

Building technology....................................................................................................................... 10 3.1

History ................................................................................................................................... 10

3.2

Structural Systems – Building Methods ................................................................................ 13

3.2.1

Loadbearing – (Nebraska technique) ............................................................................ 13

3.2.2

Frame structure (non-loadbearing system or infill bale walls) ..................................... 13

3.2.3

Light-weight frame and loadbearing............................................................................. 14

3.2.4

Straw-light clay (SLC) ..................................................................................................... 15

3.2.5

Thermal façade – Wrapping .......................................................................................... 16

3.3

4

Straw ....................................................................................................................................... 4

Straw bale Roof and floor ..................................................................................................... 18

3.3.1

Roof ............................................................................................................................... 18

3.3.2

Floor .............................................................................................................................. 19

3.4

Thermal properties ............................................................................................................... 20

3.5

Fire safety.............................................................................................................................. 20

3.6

Acoustics ............................................................................................................................... 21

3.7

Structural behavior and seismic............................................................................................ 22

3.8

Straw decomposition ............................................................................................................ 22

3.9

European Learning Partnership for Professional Training in Straw Bale Building ................ 23

Internet survey around the globe ................................................................................................. 24 4.1

Targeted group...................................................................................................................... 24

4.2

The questionnaire ................................................................................................................. 24

4.3

Method ................................................................................................................................. 25

4.3.1

Climate zones separation .............................................................................................. 25

4.3.2

Analysis of the categories ............................................................................................. 26

4.4

4.4.1

General .......................................................................................................................... 27

4.4.1

Building features ........................................................................................................... 29

4.4.2

Systems ......................................................................................................................... 32

4.4.3

Indoor climate ............................................................................................................... 33

4.4.4

Problems ....................................................................................................................... 35

4.5 5

Improvements ....................................................................................................................... 36

PAQ experiment on clay plaster and painted gypsum board ....................................................... 39 5.1

Materials and method .......................................................................................................... 39

5.1.1

Chambers ...................................................................................................................... 39

5.1.2

Specimens ..................................................................................................................... 40

5.1.3

Exposure........................................................................................................................ 41

5.2

Experimental protocol .......................................................................................................... 42

5.2.1

Questionnaire ............................................................................................................... 42

5.2.2

Panelists ........................................................................................................................ 42

5.3

6

Results ................................................................................................................................... 27

Results and discussion .......................................................................................................... 42

5.3.1

PAQ Acceptability, Odor Intensity and Irritation in the nose ....................................... 43

5.3.2

Origin of the odor.......................................................................................................... 45

5.3.3

Discussion...................................................................................................................... 45

5.3.4

Conclusions ................................................................................................................... 45

Study cases in Crete ...................................................................................................................... 46 6.1

Evaluation of thermal comfort.............................................................................................. 46

6.1.1

Criteria........................................................................................................................... 46

6.1.2

Temperature ................................................................................................................. 46

6.1.3

Relative humidity .......................................................................................................... 48

6.2

Specification of the area ....................................................................................................... 49

6.3

Study cases ............................................................................................................................ 50

6.3.1

Light straw clay house (LSC) .......................................................................................... 50

6.3.2

Traditional stone house ................................................................................................ 52

6.4

Measurements ...................................................................................................................... 54

6.4.1

Overview ....................................................................................................................... 54

6.4.2

Data analysis ................................................................................................................. 54

6.5

6.5.1

Outdoor conditions ....................................................................................................... 56

6.5.2

CO2 concentration ......................................................................................................... 58

6.5.3

Measurements of LSC during 11.08.2015 – 19.09.2015 ............................................... 59

6.5.4

Comparison of LSC and STONE during the period of 20.09.2015 – 03.11.2015 ........... 61

6.5.5

Evaluation of thermal comfort IN LSC house during 11.08.2015 – 19.09.2015............ 67

6.5.6

Evaluation of thermal comfort in LSC and STONE during 20.09.2015 – 03.11.2015 .... 68

6.5.7

Discussion on adaptive and prescriptive thermal comfort models .............................. 69

6.6 7

8

Results ................................................................................................................................... 55

Conclusions ........................................................................................................................... 69

Study cases in Denmark ................................................................................................................ 70 7.1

Outdoor measurements........................................................................................................ 70

7.2

Fri og Fro ............................................................................................................................... 71

7.2.1

Konkyliehuset ................................................................................................................ 73

7.2.2

Spunkhuset.................................................................................................................... 74

7.3

Measurements and comparison to the reference house. .................................................... 76

7.4

Air Change Rate..................................................................................................................... 81

7.5

Evaluation of indoor climate ................................................................................................. 82

7.6

Discussion.............................................................................................................................. 83

7.7

Conclusions ........................................................................................................................... 83

Energy simulations for study case in Crete ................................................................................... 84 8.1

Experiment on thermal conductivity of infill of LSC walls .................................................... 84

8.1.1 8.2

Specimens ............................................................................................................................. 85

8.2.1

Results ........................................................................................................................... 86

8.2.2

Discussion...................................................................................................................... 86

8.3

Inputs for simulations ........................................................................................................... 87

8.3.1

Climate data .................................................................................................................. 87

8.3.2

Geometry and Structural details ................................................................................... 87

8.3.3

Occupancy schedules and operation strategies ........................................................... 89

8.4

Results ................................................................................................................................... 89

8.4.1

Comparison of energy consumption between STONE and LSC houses ........................ 89

8.4.2

Optimization of LSC house ............................................................................................ 90

8.5 9

Methodology ................................................................................................................. 84

Discussion - Conclusion ......................................................................................................... 91

Straw as a solution in low-cost Renovations ................................................................................ 93

9.1

Implementation .................................................................................................................... 94

9.1.1

The Stone houses .......................................................................................................... 94

9.1.1

Thermal faรงade (wrapping) ........................................................................................... 97

9.1.2

Renovated Roof............................................................................................................. 99

9.1.3

Overall ......................................................................................................................... 101

9.1.4

Discussion.................................................................................................................... 103

9.1.5

Conclusions ................................................................................................................. 103

9.2

Existing example ................................................................................................................. 104

10

Conclusions ............................................................................................................................. 107

11

References .............................................................................................................................. 109

Appendix A. Internet survey around the globe................................................................................... 113 Appendix B. PAQ Experiment.............................................................................................................. 115 Appendix C. Thermal conductivity experiment .................................................................................. 118 Appendix D. Renovation ..................................................................................................................... 119 Appendix E. Study cases in Crete. ............................................................ Error! Bookmark not defined.

Appendix F. Study cases in Denmark. ...................................................... Error! Bookmark not defined.

List of Figures Figure 1. The nine Planetary Boundaries. (adapted by Steffen et al. Science (2015) in (Wulffeld 2015). ................................................................................................................................................................ 1 Figure 2. Final energy consumption by sector, 2010. (Source IEA, 2010). ............................................. 1 Figure 3. COP 21 Paris 2015. ................................................................................................................... 2 Figure 4. CO2 emissions in manufacturing 1kg from 24 common building materials. “Positive overall CO2 emissions indicate a net CO2 source and negative overall CO2 emissions indicate a net CO2 sink.”

(Adapted by MacMath, R. (2000) ........................................................................................................... 5 Figure 5. Common straw bales (adapted by King, 2006). ....................................................................... 6 Figure 6. Straw bale orientation. ............................................................................................................ 6 Figure 7. Sedimentation test adapted by MNBB, (2012). ....................................................................... 8 Figure 8. Absorption of samples, 15mm thick, at temperature of 21°C and sudden increase of humidity from 50% to 80% (adapted by Minke (2000). ......................................................................................... 9 Figure 9. Effect of the thickness of loam layers at a temperature of 21°C on their rate of absorption after sudden rise in humidity from 50% to 80% (adapted by Minke (2000). ......................................... 9 Figure 10. λ values of loam in density of 300-2200kg/m3. (adapted by Volhard, 1983 in Minke, 2000). ................................................................................................................................................................ 9 Figure 11. Burritt Mansion, Huntsville, Alabama, USA, (adapted by Ammons, 2013). ........................ 11 Figure 12. Pilgrim holiness Church, Arthur, Nebraska, (adapted by Carter, 2012)............................... 11 Figure 13. Strohpolis a 3 storey straw bale building in Germany (source: www.environmentandsociety.org on 11.12.2015). .............................................................................. 12 Figure 14. “Norddeutsches Zentrum für Nachhaltiges Bauen” a five-story straw bale in Germany (source: esbg2015.eu)........................................................................................................................... 12 Figure 15. Loadbearing wall system (adopted by Minke and Mahlke 2005). ....................................... 13 Figure 16. Non-loadbearing wall system adopted by (Minke and Mahlke 2005)................................. 14 Figure 17 Lightweight frame wall (adapted by Jones B., 2001). ........................................................... 14 Figure 18. Timber frame filled with straw/clay mixture. Picture adopted by "The Archanes Project". .............................................................................................................................................................. 15 Figure 19. SLC before plastering in Archanes, Crete, Greece. Picture adopted by "The Archanes Project". ................................................................................................................................................ 16 Figure 20. Thermal facade (wrapping) .................................................................................................. 16 Figure 21. Wrapping workshop in Paleokastro showcasing different methods of wrapping. Held by Minoeco and Herbert Gruber. (picture by Author). ............................................................................. 17 Figure 22. Green straw bale roof (adapted by (Minke and Mahlke 2005). .......................................... 18 Figure 23. Roof system - straw bales between rafters, with vapor barrier. (Adapted by Minke and Mahlke 2005). ....................................................................................................................................... 18 Figure 24. Roof system - straw bales between rafters, with OSB. (Adapted by Minke and Mahlke 2005). .............................................................................................................................................................. 18 Figure 25. Low budget floor construction (adapted by Minke and Mahlke 2005). .............................. 19 Figure 26. Straw bale floor – ventilated (adopted by Minke and Mahlke 2005). ................................ 19 Figure 27. Straw bale floor – ventilated (adapted by Minke and Mahlke 2005). ................................. 19

Figure 28. 45cm thick straw bale wall with a density of 120-130 kg/m3. Earth render of 2.5-3.5cm.

Compared to Concrete and sand-lime masonry walls. (Technical University of Eindhoven, Netherlands in Minke and Mahlke 2005). ................................................................................................................. 21 Figure 29 EU learning partnership for professional training in straw bale building. ............................ 23 Figure 30. Dichotomization process for indoor climate assessment ................................................... 26 Figure 31. Survey collection by region .................................................................................................. 27 Figure 32. Age of responders ................................................................................................................ 27 Figure 33. Who built it. ......................................................................................................................... 28 Figure 34. Alternative Electricity and Heating ...................................................................................... 28 Figure 35. Frame material ..................................................................................................................... 29 Figure 36. External wall's stucco material ............................................................................................ 29 Figure 37. External wall finishing material ............................................................................................ 29 Figure 38. Vapor and wind barriers ...................................................................................................... 30 Figure 39. Internal wall's stucco material ............................................................................................. 30 Figure 40. Roof materials ...................................................................................................................... 31 Figure 41. Roof type by type ................................................................................................................. 31 Figure 42. Flooring ................................................................................................................................ 31 Figure 43. Wall's Elevation from the ground ........................................................................................ 31 Figure 44. Heating system by type ........................................................................................................ 32 Figure 45. Ventilation system ............................................................................................................... 32 Figure 46. Indoor air quality in summer ............................................................................................... 33 Figure 47. Indoor air quality in winter .................................................................................................. 33 Figure 48. Sketch used to calculate the overhang's length .................................................................. 37 Figure 49. Rain screens placed. Air can freely circulate........................................................................ 38 Figure 50. Upper window flashing ........................................................................................................ 38 Figure 51. The glass chamber with a clay plaster specimen. ................................................................ 39 Figure 52. Clay plaster specimens: OSB base with first (left) and second (right) layer. ........................ 41 Figure 53. PAQ evaluation results of painted gypsum and clay plaster on acceptability, odor intensity and nose irritation. ............................................................................................................................... 43 Figure 54. Paired comparison of painted gypsum and clay plaster on acceptability, odor intensity and nose irritation. Positive values indicate hypothesis C1>G1 and C0>G0 is true. .................................... 44 Figure 55. Origin of the odor. ................................................................................................................ 45 Figure 56. Operative temperature ranges for three categories of the DS/EN 15251 adaptive thermal comfort model. ..................................................................................................................................... 48 Figure 57. Location of Archanes in Crete. ............................................................................................. 49 Figure 58. Average (24 hours mean) temperatures and precipitation in Archanes. [yr.no] ................. 49 Figure 59. Archanes village from mountain Youchtas (picture by Author). ......................................... 50 Figure 60.Visual representation of LSC house in Archanes, Crete, Greece. ......................................... 50 Figure 61. LSC house: top left – north façade, top right – south façade, middle – south façade and Mt. Youchtas and Archanes village in the valley, bottom – dining room.................................................... 51 Figure 62. LSC house: ground floor plan. .............................................................................................. 52 Figure 63. Location of the STONE house in Archanes. .......................................................................... 52 Figure 64. STONE house: left – backyard and the adjacent building from the south, right – living room. .............................................................................................................................................................. 53 Figure 65. STONE house: Ground floor plan.......................................................................................... 53

Figure 66. STONE house: First floor plan. .............................................................................................. 53 Figure 67. Outdoor temperature and relative humidity during 11.08.2015 – 03.11.2015. .................. 56 Figure 68. CO2 concentration in LSC house during 11.08.2015 – 03.11.2015. ..................................... 57 Figure 69. CO2 concentration in STONE house during 20.09.2015 – 03.11.2015. ................................ 57 Figure 70. Temperature in LSC house during 11.08 – 09.19. ................................................................ 59 Figure 71. Relative humidity in LSC house during 11.08 – 09.19. ......................................................... 60 Figure 72. Moisture content in LSC house during 11.08 – 09.19........................................................... 60 Figure 73. Temperature in LSC and STONE houses during 05.10 – 13.10. ............................................ 61 Figure 74. Temperature in LSC and STONE houses during 20.10 – 28.10. ............................................ 61 Figure 75. Temperature in LSC and STONE houses during 20.09 – 03.11. ............................................ 62 Figure 76. Relative humidity in LSC and STONE houses during 05.10 – 13.10. ..................................... 63 Figure 77. Relative humidity in LSC and STONE houses during 20.10 – 28.10. ..................................... 63 Figure 78. Relative humidity in LSC and STONE houses during 20.09 – 03.11. ..................................... 64 Figure 79. Moisture content in LSC and STONE houses during 05.10 – 13.10. .................................... 65 Figure 80. Moisture content in LSC and STONE houses during 20.10 – 28.10. ..................................... 65 Figure 81. Moisture content in LSC and STONE houses during 20.09 – 03.11. ..................................... 66 Figure 82. Outdoor measurements exported by Hobo data logger. .................................................... 70 Figure 83. Outdoor measurements plotted as a function of cumulative frequency for the period of 12.15.2015-12.17.2015 ......................................................................................................................... 71 Figure 84. Wooden house built from recycled timber and tiles. .......................................................... 71 Figure 85. Fri og fro village .................................................................................................................... 71 Figure 86. Straw bale house with green roof in Fri og Fro (picture by Author) .................................... 72 Figure 87. House in Fri og Fro built from recycled timber (picture by Author) .................................... 72 Figure 88. Straw bale house. The association's community center. (Picture by Author) ..................... 72 Figure 89. House in Fri og Fro made of recycled wood insulated with paper wool and covered with scrap scaffolding plates. (Picture by Author) ........................................................................................ 72 Figure 90. Straw bale house in Fri of Fro (picture by Author) .............................................................. 72 Figure 91. Konlyliehuset (picture accessed by Paula-Line Schmidt in 2015) ........................................ 73 Figure 92. Spunkhuset (picture by Author)........................................................................................... 74 Figure 93. Outdoor measurements for reference house plotted as a function of cumulative frequency for the period of 25.10.2010 - 26.11.2010 ........................................................................................... 75 Figure 94. Temperatures comparison plotted as a function of cumulative frequency for the period of 15.11.2015 – 17.12.2015 ...................................................................................................................... 76 Figure 95. Relative humidity comparison plotted as a function of cumulative frequency for the period of 15.11.2015 – 17.12.2015 .................................................................................................................. 77 Figure 96. Moisture content comparison plotted as a function of cumulative frequency for the period of 15.11.2015 – 17.12.2015 .................................................................................................................. 78 Figure 97. CO2 concentration comparison plotted as a function of cumulative frequency for the period of 15.11.2015 - 17.12.2015 ................................................................................................................... 78 Figure 98. Temperature daily fluctuations plotted as a function of cumulative frequency for the period of 15.11.2015 - 17.12.2015 ................................................................................................................... 79 Figure 99. Relative humidity daily fluctuations plotted as a function of cumulative frequency for the period of 15.11.2015-17.12.2015 ......................................................................................................... 80 Figure 100 Moisture content daily fluctuation plotted as a function of cumulative frequency for the period of 15.11.2015- 17.12.2015 ........................................................................................................ 80

Figure 101. CO2 decay curve for 3 days ................................................................................................ 81 Figure 102. Construction of the guarded hot plate apparatus. ............................................................ 84 Figure 103. Left – specimens in a box before drying. Right – specimen ready for the experiment. .... 85 Figure 104. Thermal conductivity measurements. ................................................................................ 86 Figure 105. Left –3D model of the LSC house. Right – 3D model of the STONE house. ....................... 87 Figure 106. Left – pergola in construction. Right – opening of a taken out window. .......................... 90 Figure 107. U-value and temperature profile calculated by U-wert. Material properties changed by the author in accordance to (Eppelbaum, L. 2014) ..................................................................................... 95 Figure 108. Humidity profile of Limestone wall calculated by U-wert. Material properties changed by the author in accordance to (Eppelbaum, L. 2014) .............................................................................. 95 Figure 109. Temperature profile of Limestone wall calculated by U-wert. Material properties changed by the author in accordance to (Eppelbaum, L. 2014).......................................................................... 95 Figure 110. Monthly delivered energy for the actual house - simulated in IDAICE software .............. 96 Figure 111. Envelope transmittion for the actual house - simulated in IDAICE software. .................. 96 Figure 112. U-value and temperature profile for a new wall element with straw insulation of 18cm calculated by U-wert ............................................................................................................................. 97 Figure 113. Humidity profile for new wall element with straw insulation of 18cm calculated by U-wert .............................................................................................................................................................. 97 Figure 114. Temperature profile for new wall element with straw insulation of 18cm calculated by Uwert ....................................................................................................................................................... 98 Figure 115. Renovated stone house (wall) - Monthly delivered energy simulated in IDAICE software .............................................................................................................................................................. 98 Figure 116. U-value and temperature profile for a new flat roof element with straw insulation of 20cm calculated by U-wert ............................................................................................................................. 99 Figure 117. U-value and temperature profile for new multi-pitched roof element with straw insulation of 20cm calculated by U-wert ............................................................................................................. 100 Figure 118. Renovated STONE house (wall & roof) - Monthly delivered energy simulated in IDAICE software .............................................................................................................................................. 100 Figure 119. Net savings (t) = cost (t) - savings (t) ................................................................................ 102 Figure 120. Wall assembly. Conic wooden spacers at every 2 straw bale rows, enhancing compression and stability......................................................................................................................................... 104 Figure 121. A 3 family house renovated with straw in Emmering, Germany, 2007 (before renovation) (accessed by Jörn Schöbe) .................................................................................................................. 105 Figure 122. A 3 family house renovated with straw in Emmering, Germany, 2016 (after renovation) .. (picture by Author) ............................................................................................................................. 105 Figure 123. Section A-A (accessed by Jörg Schöbel, 1.1.1016) ........................................................... 106 Figure 124. Roof and window detail (accessed by Jörg Schöbel, 1.1.1016) ....................................... 106 Figure 125. East/West windows size .................................................................................................. 113 Figure 126. North window size ........................................................................................................... 113 Figure 127. South window size ........................................................................................................... 114 Figure 128. Shading type..................................................................................................................... 114 Figure 129. Shadings' orientation ....................................................................................................... 114 Figure 130. Questionnaire of PAQ experiment ................................................................................... 115 Figure 131. Answers of PAQ questionnaire sorted by paramteres and exposure to smoke (1) or any (0) pallotants. ........................................................................................................................................... 116

Figure 132. Raw data of PAQ questionnaire. ...................................................................................... 116 Figure 133. Raw data of PAQ questionnaire. ...................................................................................... 117 Figure 134. Voltage through termal pile measurements for straw specimen rinsed with water (density – 38,6 kg/m3). ...................................................................................................................................... 118 Figure 135. Voltage through termal pile measurements for straw specimen rinsed with water (density – 56,2 kg/m3). ...................................................................................................................................... 118 Figure 136. Temperature profile for pitched renovated roof............................................................. 119 Figure 137. Humidity profile for pitched renovated roof ................................................................... 119 Figure 138. Temperature profile for renovated flat roof ................................................................... 120 Figure 139. Humidity profile for renovated flat roof .......................................................................... 120 Figure 140 1Rst floor (accessed by Jörg Schöbel, 1-1-1016)............................................................... 121 Figure 141. Ground floor (accessed by Jörg Schöbel, 1-1-1016) ........................................................ 121 Figure 142. Attic (accessed by Jörg Schöbel, 1-1-1016) ...................................................................... 121

List of Tables Table 1. Loam's particles defined depending the diameter. (Minke, 2000). .......................................... 7 Table 2. Thermal conductivity (Îť) tests on straw. ................................................................................. 20 Table 3. Survey completion by visitors ................................................................................................. 27 Table 4. Who built it in region .............................................................................................................. 28 Table 5. Alternative energy usage in region. ........................................................................................ 28 Table 6. Problems reported by region .................................................................................................. 29 Table 7. Wall insulation thickness in accordance with the region........................................................ 30 Table 8. Roof insulation thickness by region ........................................................................................ 31 Table 9. Heating systems by region ...................................................................................................... 32 Table 10. Indoor Air Quality perception and associated to ventilation habits ..................................... 34 Table 11. Building related problems ..................................................................................................... 34 Table 12. Percentage of problems identified in accordance to small or lack of overhang................... 35 Table 13. Chemical composition of the clay used in the experiment. ................................................... 40 Table 14. Wilcoxon signed rank test (Woolson, R. F. 2008) results for C1=G1 and C0=G0 hypotheses. .............................................................................................................................................................. 44 Table 15. Description of the applicability of the categories (DS/EN 15251, Table 1). .......................... 46 Table 16. Temperature ranges of prescriptive model (DS/EN 15251 Table A.3). ................................. 47 Table 17. Recommended humidity levels in occupied spaces (DS/EN 15251, Table B.6) ................... 48 Table 18. Occupancy, occupancy schedules, ventilation strategies for LSC and STONE houses. ......... 58 Table 19. Amount of time within categories for temperature ranges in LSC house (prescriptive model). .............................................................................................................................................................. 67 Table 20. Amount of time within categories for temperature ranges in LSC house (adaptive model). .............................................................................................................................................................. 67 Table 21. Amount of time within categories for relative humidity ranges in LSC house. .................... 67 Table 22. Amount of time within categories for temperature ranges in LSC and STONE houses (prescriptive model). ............................................................................................................................. 68 Table 23. Amount of time within categories for temperature ranges in LSC and STONE houses (adaptive model). .................................................................................................................................................. 68 Table 24. Amount of time within categories for relative humidity ranges in LSC and STONE houses. 68 Table 25. Outdoor conditions for the period of 15.11 2015 - 17.12.2015 ........................................... 70 Table 26. Occupancy schedule .............................................................................................................. 75 Table 27 Calculated Air changes per hour ............................................................................................ 81 Table 28 Thermal comfort classification according to DS/EN15251 .................................................... 82 Table 29 Relative humidity classification according to DS/EN15251 ................................................... 82 Table 30 CO2 concentration classification according to DS/EN15251 ................................................. 83 Table 31. Average monthly climate data for Heraklion. ....................................................................... 87 Table 32. Geometry and structural details of STONE and LSC houses. ................................................ 87 Table 33.External and internal walls construction definitions of LSC house. ....................................... 88 Table 34.External and internal walls construction definitions of STONE house................................... 88 Table 35. Occupancy, occupancy schedules, ventilation strategies of LSC and STONE houses for simulations. ........................................................................................................................................... 89 Table 36. Energy consumption and adaptive thermal comfort results of STONE and LSC................... 89

Table 37. Energy consumption and adaptive thermal comfort results of optimization of the LSC house. .............................................................................................................................................................. 91 Table 38. Annual delivered energy for the actual house - simulated in IDAICE software .................... 96 Table 39. Renovated stone house (wall) – Annual delivered energy simulated in IDAICE software.... 98 Table 40. Renovation Costs for Thermal façade (based on local prices, January 2016) ....................... 98 Table 41. Renovated STONE house (wall & roof) – Annual delivered energy simulated in IDAICE software .............................................................................................................................................. 100 Table 42. Renovation Costs for Thermal façade & Roof (based on local prices, January 2016)......... 101 Table 43. Thermal comfort for actual and renovated stone house. Renovated compared to the actual house................................................................................................................................................... 101 Table 44. Annual savings from heating after renovating .................................................................... 102 Table 45. Costs for renovating Jörg Schöbel house in straw. ............................................................. 106

Introduction

1 INTRODUCTION A series of devastating hazards thread environment in a global scale. Anthropogenic activities are jeopardizing the planet’s well-being.

A group of eighteen researchers from many global institutes, including the University of Stockholm and the University of Copenhagen, show that four of the nine planetary boundaries (i.e., climate change, loss of biosphere integrity, land-system change, altered biogeochemical cycles) (Figure 1) have been crossed. Moreover, three of these boundaries are not examined yet. This transgress have reached to a level where global environmental change cannot anymore be ignored. It is therefore need for a transformative change into sustainable initiatives and paradigms.

(Rockström et al. 2009).

According to Figure 2, the building sector globaly contributes to 35% of the total energy consumption and the same counts for the CO2 emissions. As a consequence, the reduction of the energy consumption by the existing buildings would be a key priority for any country and community that is struggling to save money and reduce its overall CO2 emissions. According to the European Commission, 68% of the total gas consumption comes from building stocks. The reduction of the energy consumption (EU, 2011), CO2 emissions and the energy imports from abroad can be accomplished by renovating the existing buildings.

Figure 1. The nine Planetary Boundaries. (adapted by Steffen et al. Science (2015) in (Wulffeld 2015).

Figure 2. Final energy consumption by sector, 2010. (Source IEA, 2010).

Debates in the academic circles and not only stands for demolishing the “problematic” poorly insulated buildings and building new - energy efficient ones. Nevertheless, this practice can lead to higher rates of CO2 emissions (Power, 2008). Demolishing requires energy by itself as an action, requires energy to sort out the material (trash) (recycling or not), to excavate and assemble raw materials, labor energy, transportation, etc.

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Introduction

Figure 3. COP 21 Paris 2015.

On December 12, 2015, the Conference of Parties in Paris acknowledged climate change as a real problem for the first time. 196 countries agreed to act together for a sustainable green solution for limiting global warmth. In short, the focus in the future will be to encourage both the market and the financial growth driven by low carbon investments. Moreover, in article 4 paragraph 1 of the agreement it is stated the need to achieve a balance between sources and sinks of greenhouse gasses. (COP21, 2015)

"A net CO2 sink is a material which contains an amount of carbon in its mass greater than the equivalent amount of CO2 released during related raw material acquisition, transportation, manufacture and distribution” (MacMath, R. 2000) A poorly insulated building is considered to be a source of greenhouse gasses whilst a well-insulated house built out of low embodied energy materials such as straw, it can become a sink of greenhouse gasses (Wihan J., 2007). Transforming the CO2 sources into sinks could be a very promising solution that can bring us closer towards achieving a balance.

This thesis supports the notion that straw can be a very promising material regarding the construction of new houses and the optimization of the existing “problematic” buildings.

The first chapter of this study consists of literature research. Many studies perform tests to show that structures consisting of straw can comply with building regulations for safety and comfort for many countries (e.g. Germany, Austria). After having a theoretical understanding of the physics of those structures, the next step was to investigate what is happening in practice. A survey with the help of 70 participants filling in a questionnaire showed what kind of building’s characteristics and systems that the people chose to have, and how the occupants would assess their own indoor environment.

The next chapter presents the study cases that were measured in regards to temperature, humidity and CO2 in Crete (Greece) and Denmark. These study cases are examined in order to establish a link between theory and experience in practice. Two houses in Crete, the first made of straw and the other of stone were compared in IDAICE simulation software. Optimized energy-wise solutions are provided for the straw-house. In Denmark, two straw bale houses were measured in regards to the same parameters and compared to a typical Danish conventional house. The later supports the hypothesis that straw and clay plaster regulates and keep in constant levels the indoor’s temperature and humidity.

Finally, the idea of renovating existing houses using straw as insulation was examined. The example of the stone-house in Crete is used to demonstrate approximately the annual energy savings in comparison with the expenses to build the thermal façade revealing the payback period of the investment.

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Objective

OBJECTIVE This thesis examines thoroughly the construction, potential indoor climate pollutants and hazards related to straw and clay buildings. Since in many cases those buildings are been built by nonprofessionals self-builders, it is necessary to make use of their practice and investigate the potential of these buildings. In recent years, many researchers have proposed changes that are strongly related to the renovation of existing conventional houses. Furthermore, an important aspect to examine is whether the use of straw and clay can be feasible concerning energy savings.

The following questions about straw and clay buildings are raised and examined throughout the report:      

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How do they perform regarding indoor climate and energy consumption?

Can the selected case studies confirm the theoretical background?

How do clay and straw perform in different climates? Is a warm and humid climate challenging the indoor environment? How would it be for a cold and humid environment?

In comparison to local conventional/traditional buildings, are these structures performing in a better or worse way?

Can an energy-wise-renovated house with a great amount of thermal mass (suitable for warm climates) withstand the excessive heat stored within its structure?

What is the payback of a renovation case study?

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2 CONSTRUCTION MATERIALS 2.1 STRAW 2.1.1

WHAT IS STRAW?

Straw is the agricultural waste product after the grain and chaff have been removed from the cereal plants. Straw is about the half of the total cereal crops that is not used by the farmers cultivating rice, rye, wheat, barley and oats. Straw is a tubular plant structure, between the root system and the grain head. In fact, straw and hay are different. Hay is grown especially for feeding livestock and cut before seed. In many places, e.g., New Zealand, the farmers are burning the straw because as they report, the crop will produce more the upcoming year. This, however, is proven wrong in Williams et al. (2013) Straw bales (straw compressed and wrapped together) are a byproduct of our food production, which according to the Food and Agriculture Organization of the UN (FAOSTAT, 2013) is the largest food group for human consumption.

Straw is a lignocellulosic material, like wood, consisting of the following constituents. Cellulose (about 40% of its volume), hemicellulose (approx. 25%), Ash (approx. 20%), lignin (approx. 15%) and possesses a waxy, water-repellent skin.

Building-wise, each type of straw gives different characteristics. For instance, barley straw performs best among the rest, in regards to thermal insulation. Rice straw, which has the highest concentration of silica, is more resistant to decay. Due to the slightly barbed surface of rice straw, the straw fibers have the effect of “grabbing” each other and hence the straw bales will have a better coherency.

2.1.2

EMBODIED ENERGY AND CO2 EMISSIONS

(Embodied energy is the energy that is used throughout whole production chain giving an indication of the greenhouse gas emission levels).

Straw is a renewable and regenerated resource with an extremely low embodied energy, especially when it is compared to other building materials such as bricks, steel or concrete. Straw’s embodied energy is 4 kW/m3 whereas the conventional bricks’ is 1462 kW/m3 (Brojan, 2013 in Kalogiannaki E. 2015)

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Figure 4. CO2 emissions in manufacturing 1kg from 24 common building materials. “Positive overall CO2 emissions indicate a net CO2 source and negative overall CO2 emissions indicate a net CO2 sink.” (Adapted by MacMath, R. (2000)

The embodied energy of baled straw is 0.24MJ/kg (Magwood, 2004 in Wihan J., 2007). Since, 1MJ of embodied energy equivalent to 0.098 kg of CO2 (Balderstone, 2005 in Wihan J., 2007), baled straw yields 0.023kg of CO2.

Wihan J. (2007) showed that straw has a 60% of carbon by weight. In contact with oxygen, 1 kg of carbon produces 3.7 kg of CO2 (Wilhelm, 2004 in Wihan J., 2007). Hence, 0.6*3.7 yields 2.22kg of stored CO2 in 1kg of straw. When the stored CO2 is deducted from the straw’s embodied CO2 per 1 kg of straw, it is clearly seen that straw has a -2.197 of CO2 emissions.

Wihan J. (2007) in his calculations proves that “the local straw is a net CO2 sink” (Wihan J., 2007).

Gonzales (2013) in his study case in Patagonia proved that the embodied energies and CO2 for a straw bale structured wall and for a wall covered by straw/clay blocks are 28MJ and 2.5kg CO2e/m2 and respectively 40MJ and 3.4 kg CO2e/ m2. For a common wall made of fire bricks, those values would be 141 MJ/m2 and 38 kg CO2e/m2(Gonzales, 2013). These results change in different studies since the embodied energy is influenced by a number of factors change according to the type of construction.

Those factors might be the distance that the transportation of the materials took place, the machinery for baling the straw, usage of pesticides and many other.

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Figure 5. Common straw bales (adapted by King, 2006).

2.1.3

STRAW BALES

The bales are the masses of straw compressed by a machine into rectangular or circular blocks. Metal wires or polypropylene twines are used to hold the bales together. Some builders refer to the number of strings when they refer to the bale size. 2-string or 3-string are the most common but also larger bales that are used for building purposes.

There are numerous debates around the world on the way that straw bales are stacked to build a wall (TLSJ, 2014). It can either be flat stacked, on-edge or on-end. All have different advantages and disadvantages and, therefore, the application can vary depending on the needs. 

Flat orientation signifies that the bales are placed with the longest dimension parallel to the wall, and the bales wide dimension creates the wall’s width.  On-edge placement signifies that the shortest bale’s dimension defines the wall’s thickness.  On-end placement signifies that the bale is standing vertical having the longest dimension to the height of the wall.

Orientation defines the number of bales, the Figure 6. Straw bale orientation. thermal performance, the thickness of the wall (wall footprint), the wall’s stability and the string exposure on the wall’s surface.

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The Last Straw journal released a survey that showcases the preference of 46 builders in relation to the orientation of the bales. 43% of the participants use bales laid flat and 23.6% use them on-edge while there was one single answer for the on-end orientation. 19.6% answered that it depends on the project. The participants were in their majority self-builders but also architects, contractors, engineers and skilled laborers. (TLSJ, 2014)

2.2 CLAY 2.2.1

WHAT IS CLAY?

Clay or more accurately spoken loam, is the product of eroded rock in the interior of the earth. Erosion occurs due to natural mechanisms like the movements of water, glaciers (sheet, rill and gully erosions) and winds. The mass movements like landslides and avalanches are not only removing the topsoil but also a great mass of earth and rocks, forcing rocks to grind and break. Other types of erosion occur due to expansion and contraction of freezing water or the rock itself due to low-temperature hydrothermal alteration. Generally grinding mechanisms or weathering mechanisms are those who are responsible for the erosion of rock to occur.

The mixture of different kinds of soil types, such as clay, silt, sand and gravel or stones is called loam.

The particles’ size varies and defines the type of soil.

Table 1. Loam's particles defined depending the diameter. (Minke, 2000).

Loam mixture Clay Silt Sand Gravel and stones

Particle in diameter <0.002mm 0.002mm - 0.06mm 0.06mm - 2mm >2mm

The consistency of the different proportions of soils in the loam is defining the mechanical properties.

Clay in less than 15% of the total weight is considered as lean clayey and more than 30% rich clayey soil. (Minke, 2000) Clay consists of different minerals that are hydrous aluminum phyllosilicates. Magnesium, iron and alkali metals are some of them. Iron gives the red or yellow color on clay, magnesium and lime give a white essence while manganese and organic compounds give a brown or black color.

Clay is the part of the loam that binds everything together as concrete whilst the rest acts as aggregates. The presence of water in the mixture activated the binding action of loam. Loam is lighter that the rest, next comes silt and the heavier compound â&#x20AC;&#x201C; apart from stones and gravel â&#x20AC;&#x201C; is the sand.

In order to avoid organic plant matter, it is suggested to dug out the clay 40cm below the ground level.

The density of the freshly taken clay is 1000-1500 kg/m3. When it is compressed together for instance in soil blocks it is 1700-2200 kg/m3. (Minke, 2000)

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2.2.2

COMPOSITION TESTS

The composition of loam is needed to be known for particular applications. Many tests have been evolved over time in order to help builders to approximate the mechanical properties for the needs of the construction.

These tests are giving results that are rather fast and can be done in situ than accurate.

By using those tests, one can indicate the presence of organic matter, humus, and whether the mixture is sandy or silty. There is also acidity test that reveals the presence of lime. Most of them rely on our human senses. By Figure 7. Sedimentation test adapted by MNBB, smelling the mixture, one can understand the presence (2012). of organic matter and by feeling the mixture on the hand, it can tell if large gravel is present and by rinsing whether the mixture is sandy or silty. Other tests, such as the sedimentation test, approximate the consistency but they also can lead to errors up to 1700% according to the University of Kassel.

(Minke, 2000) 2.2.3

FACTS ABOUT LOAM

Minke (2000) summarizes through experiments and studies what is known about loam as a building material.

Loam is used for thousands of years as a building material with reference buildings going back in 80006000BC (Pumpelly (1908) in Minke (2000)) in Turkistan and 5000BC in Assyria. Other historical examples of earth being used as a building material could be the temple of Rameses II at Gourna, Egypt 3000-2000 years ago and the 4000 years old Great Chinese wall that was originally built on earth and later covered with stones and bricks. In Teotihuacan, Mexico the core of the Sun Pyramid was built with approx. 2 million tons of rammed earth. (Minke, 2000) Although materials from earth are used for thousands of years in the building sector, these are not yet used widely as building materials. Since loamâ&#x20AC;&#x2122;s composition and properties change from place to place, it is hard to use them in a standardized way.

These materials that can be reused if they stay unburned. Walls made of earth are normally hardened by outdoor conditions. When they are placed back in the water, they become soft again, regaining the original plasticity and the rest of their mechanical and physical properties. Therefore, loam cannot be considered as a waste which can threat the environment. Moreover, it requires only 1% of the energy to have it ready to use in situ of the energy used to manufacture and transport industrialized products such as burned bricks or reinforced concrete. Therefore, greenhouse gasses emissions are reduced significantly.

Another important fact is that loam preserves timber and other organic materials that are in contact with it. Both the low equilibrium moisture content (EMC) of 0.4% to 6% by weight and the high capillarity that loam possesses, helps the organic matter to be kept dry and not being attacked by fungus or insects.

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Nevertheless, when using loam for exterior surfaces, it is necessary to protect it against water since it has no water resistant properties.

Due to its high specific heat (cp) of 1.0 kJ/kgK (Minke, 2000), loam can store significant amounts of heat into its structure. The higher the density the more capable of storing heat.

The insulation properties of loam alone are poor because of its high density. The presence of air improves the thermal insulation properties.

Regarding the indoor air quality and comfort, loam regulates the air humidity. A study case of a house in Germany where interior and exterior walls w made of earth showed that the indoor relative humidity was kept constant at 50% all year long with a small fluctuation of 5-10%. The University of Kassel conducted experiments showing that in a wall made of mud bricks, the first 1.5cm thick layer is able to absorb about 300g of water per m2 of the wall surface in 48 hours when the humidity was increased suddenly from 50% to 80%. Under the same conditions, the gypsum absorbs 26-76g/m2 and burned bricks only 6-30g/m2. (Minke, 2000)

Figure 9. Effect of the thickness of loam layers at a temperature of 21°C on their rate of absorption after sudden rise in humidity from 50% to 80% (adapted by Minke (2000).

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Figure 10. λ values of loam in density of 3002200kg/m3. (adapted by Volhard, 1983 in Minke, 2000).

Figure 8. Absorption of samples, 15mm thick, at temperature of 21°C and sudden increase of humidity from 50% to 80% (adapted by Minke (2000).

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3 BUILDING TECHNOLOGY A straw bale wall can be made by putting together the straw bales in a specific way and covering the external surfaces with stucco that that consists of earth/clay or lime, or even cement stucco.

3.1 HISTORY Since the 1990s, the techniques of straw bales started to gain popularity. It is documented to have its pioneer roots in Nebraska’s sandhills in the USA, back in the late 18th century (Steen, 1994). The inhabitants of Nebraska valley were cultivating cereals in a landscape without stones or timber waiting for the arrival of timber via trains at spring time. This gave them the option to build temporary houses made of straw bales, which was a material in abundance. Soon this building technique expanded and builders of that time took it seriously evolving a loadbearing technique, that was later called “Nebraska technique”, that allowed them to carry their roofs onto the straw giving the flexibility to be less dependent on timber. 70 buildings were counted from that period but only 13 were survived after 1993 (Welsch, (1970), cited by Minke and Mahlke, (2005).

Afterwards, it spread to Canada and Australia. Thereinafter, straw bales hooked the interest of Europe and gradually reached Asia and South America. The oldest known straw bale building in Europe was built in 1921 (France). It is a 100 m2 house in Montargis, France known as “Maison Feuillette” (Minke and Mahlke 2005).

The trigger for this building type came since big machinery took over the straw harvest and compressed it, into same dimensioned blocks - bales. This fact made easier to work with this material since the size, compression and hence properties did not differ much from the same farmer’s bales.

The first known two-story structure was built in 1930 (the Huntsville, Alabama, USA). This building functions as a museum today and is named Burritt Mansion. Despite the highly humid climate with very intense rainfalls, it is still standing. (Myhrman & MacDonald, 1997) This exponential increase of interest during the last decade for these buildings is the result of having so many examples throughout the globe, and a small but steadily increase of a number of books and academic research on the topic.

German and Austrian universities were the first (at least in Europe) to study intensively this topic and yield to raise trust towards straw and clay and moved forward to standardize those materials in their national building regulations.

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Figure 11. Burritt Mansion, Huntsville, Alabama, USA, (adapted by Ammons, 2013).

Figure 12. Pilgrim holiness Church, Arthur, Nebraska, (adapted by Carter, 2012).

Pilgrim Holiness Church is a well-known baled biomass building in Arthur, Nebraska. This church is constructed of rye straw bales during 1927-28. Today it serves as a museum. (Carter, 2012)

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Figure 13. Strohpolis a 3 storey straw bale building in Germany (source: www.environmentandsociety.org on 11.12.2015).

Strohpolis is three story straw bale building which was built in 2005 by the architect Dirk Scharmer. It is located in the eco-village Sieben Linden in Germany, consisting of 539 m2 of floor area and was built with the method of a Straw bale infill structure. The walls made of straw bales of 0,49 x 0,36 x 0,85m were used achieving an U-value of 0.14 W/m2K.

Figure 14. “Norddeutsches Zentrum für Nachhaltiges Bauen” a five-story straw bale in Germany (source: esbg2015.eu)

The North German Center for Sustainable Construction (NZNB), built by the architects Thomas Isselhard and Dirk Scharmer, is the first plastered straw bale structure of five stories in 2014 consisting of a floor area of 1800 m2. The project costs were 4.4 Million Euro. The achieved annual energy consumption per square meter is less than 10 kW/h. (Youtube, 2015) 12

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3.2 STRUCTURAL SYSTEMS â&#x20AC;&#x201C; BUILDING METHODS 3.2.1

LOADBEARING â&#x20AC;&#x201C; (NEBRASKA TECHNIQUE)

During the loadbearing technique, the loads from the roof are carried by the straw bale walls and are transmitted into the foundation.

The main reason for building in this way is simplicity. This method is the most fun way of building with bales, requires very little knowledge of constructions, therefore, it is accessible especially to self-builders.

Other reasons include the use of timber gets much lowering the price of the project. Mistakes can easier be corrected even in later stages. Curves and non-square shapes are not hard to achieve for a little extra cost. Less technical skills and planning efforts are required. Finally, the building erection takes less time since carpeting is less demanded.

A disadvantage that gives space for questioning this method to use is the fact that during the building process the walls are exposed to weather Figure 15. Loadbearing wall system (adopted by Minke and Mahlke 2005). conditions and, therefore, the planning is harder.

This method is generally not suggested for large constructions. Another limitation is that the aperture area cannot exceed 50% of the total wall surface and the maximum spanning is 6 meters. (Wanerk C., 2003) Many countries are not giving building permissions for this method due to lack of authorization even though there are no proofs of fire, stability or durability hazards. Local planning authorization seems to be closer to superstitious perception rather than reasonable scientific argumentation. In the meantime, other European countries have adopted their permission like Great Britain, Austria, Denmark, France, Ireland, Holland and Switzerland.

3.2.2

FRAME STRUCTURE (NON-LOADBEARING SYSTEM OR INFILL BALE WALLS)

In this technique, the loads are transmitted to the foundation through the frame that is either timber, steel or even reinforced concrete. The role of the straw bales is serving only for insulation purposes, no structural value.

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This way of building is favoring larger, taller and more complicated structures. The advantage over the loadbearing technique is that the roof can be finished before dealing with the bales. In this way, the bales have a dry, weatherproof place to be stored and the work is not weather dependent anymore. Another reason that it can be preferable building technique is that since the frame is made out of conventional materials, timber, steel or concrete, it can be more suitable for countries where the building regulations can pose problems. The bales can be placed either on the outside of the framing or frame-type or around it. Windows and doors, in this case, are integrated into the frame. (Jones B., 2001) Figure 16. Non-loadbearing wall system adopted by (Minke and Mahlke 2005).

There are some disadvantages over the Nebraska method, such as the requirement of wider foundation and deeper embrasures. High level of carpentry is required in this method and the large amount of timber sometimes is a reason to opt out this method.

Other reasons are the man power required to lift and place the whole straw bales, and the possible holes in the corners are adding problems to plastering afterwards.

3.2.3

LIGHT-WEIGHT FRAME AND LOADBEARING

Barbara Jones B. was the pioneer of this method that took into account a way of using the loadbearing method by taking out the disadvantage of the weather dependence. She introduced this method that uses a light-weight timber framework that will temporarily secure the roofing system. By using temporary bracing and/or acrow props to ensure stability until the straw bales are placed. Straw and timber work together in carrying the vertical loads from the roof. Timber posts are placed in corners and on the side of openings. Compression of the straw bales increases the rigidity, hence the more compressed they are the better. Therefore, the straw bales are suggested to be placed externally that is more feasible to be compressed after the Figure 17 Lightweight frame wall (adapted by Jones B., 2001). bracings are taken out.

This method provides greater stability for openings than the loadbearing method while exposure to weather condition is not present. Moreover, the framework can be built off site. Compared to the post and beam method the amount of timber is reduced.

A disadvantage is that for some parts technical knowledge is required. (Jones B., 2001)

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3.2.4

STRAW-LIGHT CLAY (SLC)

Straw-light clay is a technique that is using many elements of techniques that are evolved through history from many civilizations. Many examples can be found in Africa, Asia, Middle East, Europe and America. There are many buildings that are still standing and were built 500-1000 years ago with earth as the main material and often being mixed with straw and other fibers. Very often as well there is a combination with timber framing.

The last years there is, small but rapidly growing, need to research those techniques and making an effort in quantifying the material properties of the SLC. It is a technique that utilizes loose straw and clay into a wooden framing. For this technique clay and straw are mixed with many proportional variations giving different results in terms of thermal properties. The straw/clay mixture is stuffed in between of the timber frame as can be seen in Fig. 18 Small horizontal studs are used to secure the mixture into the buildings frame.

Figure 18. Timber frame filled with straw/clay mixture. Picture adopted by "The Archanes Project".

According to Minke (2000), a light straw clay walls have a density from 400 to 1200 kg/m3. The German standards (DIN 18951) refer to lightweight loam when clay with lightweight aggregates is in density less than 1200 kg/m3. The more fibers are used the less clay is needed and the mixtureâ&#x20AC;&#x2122;s density becomes smaller. When the clay presence is less, the thermal properties of the mixture are enhanced.

The low amount of clay means that the mixture is just wet straw with water containing clay. By rinsing the straw with water, it releases the silica that bonds the straw together in a hard block form. This ability of the straw is taken into consideration for many builders that are building blocks/bricks that are used in the same way as traditional brickwork techniques are done.

Making use of thermal mass and thermal insulation, builders can easily customize the wall systems in different ways according to the design. Variation such as the use of wood chips, seaweed, reeds, sawdust cork or other materials are used as well.

The amount of straw used is less in comparison with a straw bale structure and no special machinery or tools are needed. The actual building process is taking less effort and lower material costs. It requires less manpower to place the insulating material and buildings can be built with a higher level of accuracy compared to the Nebraska technique.

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Figure 19. SLC before plastering in Archanes, Crete, Greece. Picture adopted by "The Archanes Project".

A problem that is often encountered is the time needed for the wall to dry out. Unlike to straw bale structure, the insulation here needs to be dried out before being rendered. In theory, it seems a very time-consuming process, nevertheless, if planned correctly it does not prolong the process. When the last wall is ready filled, the first wall is usually dried out and ready for plastering.

3.2.5

THERMAL FAĂ&#x2021;ADE â&#x20AC;&#x201C; WRAPPING

This technique is used for renovation purposes. It has been developed the recent years low-cost renovation, which is considered by many households. Local workshops are expanding the knowledge and leave space for evolving the technique in alternative materials. Vertical studs are attached to the original façade and straw bales are squeezed in between of them. Width between the studs is determined by the size of the bales. If the thinner layer of insulation is desired that the smaller dimension of the straw bale, bales are gently untied and flakes of straw are desired thickness is used.

Horizontal battens secure the infill between the studs as it is more loose material.

Figure 20. Thermal facade (wrapping)

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Instead of timber battens wood wool or other boards (heraklith), tied bamboos or reeds, etc. can be used. Afterwards, lime or clay plaster with limewash or other water repellent technique is used for the finish. On the bottom of the structure, gravel is placed to make sure that any paternal water can drain and move freely to find its egress.

Figure 21. Wrapping workshop in Paleokastro showcasing different methods of wrapping. Held by Minoeco and Herbert Gruber. (picture by Author).

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3.3 STRAW BALE ROOF AND FLOOR 3.3.1

ROOF

Flat roofs are not recommended, since their detailing and the upcoming maintenance will be a hard task, moreover, the risk of leaking is still huge.

It is highly recommended to design large overhangs that will protect the wall system from the driven rain. There are no good arguments for not using large overhangs neither for cold nor for warm climates. The overhang will protect the earthen plastered wall from being washed out or the cement stucco of getting water saturated.

Rainwater can penetrate either horizontally from the walls or vertically from a malfunctioned roof-to-wall joint. The difference is that in the first case where water comes in horizontally, the straw bales will get wet on their surface and not further in. This amount of water will quickly dry out whereas the vertical water penetration can lead to serious mold problems since the water flows directly to the core of the straw bale where it is very hard to dry out.

Figure 22. Green straw bale roof (adapted by (Minke and Mahlke 2005).

The general design of the roofing system for this type of buildings is not particularly different to the one of other conventional buildings.

If straw bales are to be used for the roof, it has to be taken into account at the planning stage that the height of the rafters is equal to the height of the chosen bale and the distance from rafter to rafter should be equal to the length of the straw bale. This will simplify the structure and a simple installation will be feasible.

Figure 23. Roof system - straw bales between rafters, with vapor barrier. (Adapted by Minke and Mahlke 2005).

The U-value of a roof structure with a 35cm in height straw bale, will around 0.14 to 0.16 W/m2K. (Minke and Mahlke 2005) Green roofs (Fig. 22) are not causing any problems.

Neither concerning the loads nor the moisture propagation as long the design and the proper Figure 24. Roof system - straw bales between installation is done correctly. The root barrier will keep rafters, with OSB. (Adapted by Minke and Mahlke the direct contact with soil, moisture and rooting system 2005). away from the straw bales.

The typical build-up can be seen in Figures 23 & 24 can be seen the typical roof build up. It normally consists of panels below the rafters with a vapor barrier. In case for preferring a lower budget roof, OSB or Heraklith boards can be used since they have a high resistance to water vapor diffusion.

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3.3.2

FLOOR

Straw bales have been used as floor insulating material since a long time and proving a tight shield effect for the structures. There are some considerations before choosing to do so.

It has to be ensured that no rising moisture can occur from the ground. This can be avoided by several ways. A low budget floor construction would be to place the bales on pallets that are further placed on tires or other materials acting as spacers. Another way could be to place them on top of a thick layer of sea shells or similar materials which have a very low capillary action.

Figure 25. Low budget floor construction (adapted by Minke and Mahlke 2005).

To prevent the formation of condensation, it is important to install vapor barriers under the bales.

According to Minke and Mahlke (2005), the most economical solution for flooring (Fig. 25) that was tested at this test building consists of 10cm heavy gravel directly on the ground, covered with 3cm of sand layer and a moisture barrier. Pallets are used to ensure the ventilated cavity. Above the straw bales can be laid OSB boards, and the joints will be finally sealed with the use of the second layer of OSB on top.

Figure 27. Straw bale floor â&#x20AC;&#x201C; ventilated (adapted

by Minke and Mahlke 2005).

Figure 26. Straw bale floor â&#x20AC;&#x201C; ventilated (adopted by Minke and Mahlke 2005).

Another important parameter is to make sure that the wall will not come in contact with the ground level. As can be seen in the Figure 26, the suggested elevation is above 30cm. The reason for this is to avoid the capillary action that is often the case of a washed out earthen stucco. This is very often the case where moisture is formed on the lower part of the wall.

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3.4 THERMAL PROPERTIES Due to three factors the thermal properties can be found different.

The major factor is the density, the second is the position of the fibers and the last in a lesser degree is the humidity content. In accordance to Minke and Mahlke (2005), the humidity content in the straw has to be less than 15%.

Depending on how the bales are orientated, the insulation properties differ. A straw bale of the same density was measured in regards to λ-value placed with the fibers orientated horizontally and vertically to the wall.

Table 2. Thermal conductivity (λ) tests on straw.

Density, ρ (Kg/m3)

Current study(1)

38.6-56.2

Thermal conductivity, λ (W/mK) Straw parallel to heat Straw perpendicular flow to heat flow 0.044

Current study(2)

45.9

0.056

Munch & Møller, (2004) Munch & Møller, (2004) Minke and Mahlke (2005) Haus der Zukunft (2000) in Munch & Møller, (2004) McCabe (1993) in Munch & Møller, (2004) Sandia National Lab. (1994) in Munch & Møller, (2004)

75

0.057

0.052

90

0.060

0.056

Unspecified

0.060

0.045

Reference

(1)Loose (2)Loose

100

0.038

Approx. 150

0.060

0.048

90

0.05 or 0.06 (unspecified straw direction)

0.05 or 0.06 (unspecified straw direction)

straw rinsed with water. straw rinsed with clayey water.

3.5 FIRE SAFETY A number of tests with respect to fire safety was conducted by many universities and authorized research institutes around the world. Specimens were imposed to fire by testing the performance of the unplastered straw bales, plastered straw bales with different finishes and the plaster itself.

After a number of tests, Theis (2003) showed plastered straw bale walls to have high abilities to resistant to fire damage, flame spread and combustion.

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San Rafael concluded that the specimens imposed to the fire test of 2 hours met the criteria for the fully indicated fire resistance period. The non-loadbearing wall system constructed of wheat straw bales and with 2.5 cm earthen-plaster finishes of 1.2kg/m3 density met successfully the conditions of acceptance. (San, 2007) According to Theis (2003), the “counterintuitive” assumption that a straw bale wall would be suitable as a fire safe material, is strongly argued that “straw is so obviously flammable”. However, fire requires 3 elements: high temperature, fuel, and oxygen.

The compressed straw that comes with a density of 100-120 kg/m3 effectively decreases the oxygen’s ability to feed a fire. Generally, the bales are plastered on both faces to enhance the fire resistivity of the total wall system. The combination of an incombustible surface and an insulating body that does not burn well or melts, brings the straw bale wall to a “very fire-resistive assembly” (Theis, 2003) and possessing the title of “normal inflammability”(Minke and Mahlke 2005).

Austria, Germany, and USA tests rate a loadbearing wall system with earthen render on the interior and lime on the exterior, to an F90 fire rating. (DIN 4102 - B2 / EN 13501) Fire tests regarding the plastercan demonstrate that already an 8-10 mm thick clay plaster yields in a fire-resistant component (DIN 4102 F30) and a flame-retardant surface (B, s1, d0 according to EN 13501-1: 2007). (Scharmer, 2015) Furthermore, from both technically speaking but also building’s regulation-wise, the five-story North German Center for Sustainable Construction (NZNB) building made of straw bales, which was finished in 2014, successfully complied with the regulations for fire safety.

3.6 ACOUSTICS A noise level difference of 43-55 dB was measured for a wall system of 45 cm thick wall earthen rendered on both sides in the Austrian university GrAT by John Glassford. The wall sample was exposed to a frequency spectrum of 500 to 10000 Hz. (Glassford in GrAT, 2001 in Minke and Mahlke 2005) In Denmark measurements were conducted in an existing house in both wall type, straw placed horizontally (straw fibers perpendicular to the plane of the wall) and vertical (straw fibers parallel to

Figure 28. 45cm thick straw bale wall with a density of 120-130 kg/m3. Earth render of 2.5-3.5cm. Compared to Concrete and sand-lime masonry walls. (Technical University of Eindhoven, Netherlands in Minke and Mahlke 2005).

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the plane of the wall). Both were rendered with 4cm of clay. The former showcased a sound reduction index of R’w=52 dB while the later was found to be R’w =46 dB. (Møller, 2006) The flanking transition was measure to obtained values of 53-54dB where the Danish regulations state that for separation walls from apartment to apartment is 52dB and for walls that adjoin two nondetached houses is 55dB (Møller, 2006)

3.7 STRUCTURAL BEHAVIOR AND SEISMIC “The remarkable ability of plaster to resist high in-plane loads was demonstrated during the testing, as was the ability of this material to resist these loads multiple times.” (Obispo SL. 2000) After Kashmir, the devastating earthquake that registered a moment magnitude of 7.6 in Pakistan pm 2005 killed 100,000 people and left 3.5 million people homeless. Pakistan Straw Bale and Appropriate Building (PAKSBAB), among others researched deeply straw bale structures under the seismic loads.

The typical houses that did not withstand the earthquake were in their majority single of two story stories of reinforced stone, masonry concrete blocks or solid bricks. The University of Nevada, Reno (UNR) on 2009 offered their facilities to investigate whether straw bale structures would withstand Kashmir and if it could be a solution for a region with a seismicity as it is in Pakistan.

A full-scale straw bale house was subjected to the shake table simulation. The test-house was single story straw bale walls plastered with clayey soil, chopped straw and reinforced by fishing net. The roof was made of corrugated metal sheets and for the foundation was used sacks of gravel inside a mortar consisted of soil, sand and cement. Snow loads on the roof were substituted by gravel bags that were placed on the roof.

The structure survived after being subjected to 8 earthquakes. With the last being at accelerations of 0.82-g, stronger than the ones at Kashmir earthquake. It made minor damages such as having flakes crumbled off and the plaster cracked. (Donovan et al, 2009) Mar’s (1998) test proved that the prototype vault could meet the strength requirements of the local building code, and also satisfy the code concerning the toughness, the energy absorption, the stability and the safety. Furthermore, it also successfully demonstrated that one could achieve a good structural performance by using composite straw-bale, stucco and wire mesh construction just by utilizing basic engineering principals and mechanisms that using straw as the key component.

Faine’s (2000) full-scale test on the Nebraska style wall showcased that a load-bearing wall system for two stories for residential purposes was subjected to laboratory failure test and complied with the local building regulations. The ultimate failure load was at 73 kN while the safe working load was 40 kN. The equivalent safety factor was 1.82. Regarding the serviceability, it was concluded from the test, that a big influential factor is the compressions of the bales.

3.8 STRAW DECOMPOSITION (Wihan J., 2007) investigated this topic through different approaches such as, computer simulating models, statistical analysis from a questionnaire that was sent to professionals and through his study cases, and literature research.

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His report concludes that even with outdoor’s relative humidity of 78%, the walls of his study case will not provide enough moisture for the microorganisms to break down the straw structure. In order to have a significant straw decomposition, it is needed a long-term water supply ( an environment with relative humidity close to 100%) to the microorganisms.

Wihan (2007) found out that the most frequent source of long-term moisture within the straw bale walls is because of a poor detailing of fenestration and from leakages from a not well-executed roof.

Although driving rain is a causing problem, Wihan’s (2007) findings suggest that is not jeopardizing the straw since it is a short time source and the needed time to dry out is enough. Neither is a problem the condensation due to water vapor diffusion for the same reason.

From Wihan’s (2007) WUFI model it is concluded that in a cold and humid climate, earthen plastered straw bale that is dipped in 50mm of a clay slip at the side of the bales coming in contact with the plaster ensures the driest environment for straw within a wall. Furthermore, for the same climate, it was found that earth plaster is better in keeps lower moisture levels within the straw bale wall rather than lime plaster.

From his survey, it turned out that 72% of the professional straw bale builders would not hesitate in building straw bale buildings in hot and humid climates. Nevertheless, his simulations in his study case showed that on that climate different wall assemblies are performing the same regardless of the plaster type by having the peaks of 98% in the straw that adjoins the interior plaster.

3.9 EUROPEAN LEARNING PARTNERSHIP FOR PROFESSIONAL TRAINING IN STRAW BALE BUILDING A need of professionals straw bale builders was obvious as the interest on this house-types is growing.

Moreover, in order to have residential buildings complying with the EU building code, builders need to have to have basic knowledge. Straw bale association in Europe gathered and brought this need to the surface.

The European Union through the “Lifelong Leaning Programme” is offering courses to professional builders, architects, and engineers who want to become trainers. The aim of it is to establish a straw bale building practice on a European level that can be spread as a coherent knowledge through certified and professionalized courses and workshops. Partners from 9 European countries (FASBA, ASBN, SBN, ARTUR, RFCP LES COMPAILLONS, RCP, STRAWBUILD, COMPLHA and MAGYAR SZALMAÉPITOK EGYESÜLETE) exchange visions, information, knowledge, studies and experience in different techniques for the common objective to promote straw bale building as a sustainable and innovative building method.

Introductive but also specialized courses covering topics in “infill and prefab”, “loadbearing”, “wrapping”, “finishes”, “building physics and sustainability” “concept for the house/design and maintenance” and finally “marketing and communication” are held by the program. The courses last from few days to few weeks and are done through lectures, talks, practice and workshops.(Lifelong Learning Programme, 2016).

Figure 29 EU learning partnership for professional training in straw bale building.

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4 INTERNET SURVEY AROUND THE GLOBE A global survey was distributed to straw/clay house owners in order to examine how this buildings are performing regarding their indoor environment in a perception based assessment. As was studied in precious reports, many surveys were carried out in the past but the targeted group was architects, engineers and professional builders. However, a big portion of those houses are been built by the owners themselves and hence asking professionls might not reflect the absolute reality. As Clay/straw buildings, especially for residential purposes, are thieving the latest years it is important to apply more scientific approach towards the observed trend.

4.1 TARGETED GROUP The participants were found through: 

    

Straw bale associations and Networks of California, Colorado, Nebraska, Ontario, Texas, European Straw bale Network, Austria (ASBN), Belgium, Czech Republic, Denmark, Estonia, France, Germany, Holland, Hungary, Italy (EDILPAGLIA), Norway, Romania, Switzerland, United Kingdom (WISE) , Australia & New Zealand (AUSBALE), GEN-Europe, GEN-International and The Global Straw Building Network (GSBN) International Straw Bale Building Registry (1654 households being registered) Blogs and Journals such as The Last Straw blog and okosamfund.dk Facebook groups on the topics of straw/clay buildings, ecology, architecture, eco villages, permaculture and so on.

Architects, individuals and groups who are leading this field By word of mouth

4.2 THE QUESTIONNAIRE The questionnaire consists of 165 questions. Yes/no, multiple answer and text questions were asked.

At this point, it should be mentioned that the questionnaire was distributed either in a full version or in a format of mandatory questions (indoor environment section). The latter format could be answered in 5-10 minutes. Surprisingly, all the participants filled in the full version and had an average completion time of 35minutes.

Due to the fact that there is a large interest of straw bale buildings from Austria and Germany, the questionnaire was translated into the German language. Moreover, the questionnaire was translated into Lithuanian and French.

Furthermore, the questionnaire was separated in the following four interrelated categories:    

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Building features Systems Problems Indoor environment

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All these categories focus on identifying and gathering a large dataset without having in situ assessments. The investigation took place in order to find out how structural problems, casual habits, energy systems can interrelate with indoor climate issues.

Building features Participants were asked to specify information such as how long time they lived in the house, location, building type, who built it (professionals or themselves), dominants wind’s direction, what kind of materials were used, presence of overhang, roofing, flooring, wall systems and so on.. The purpose of this section was to give a general understanding of the structure, the surroundings, weekly oriented walls that were expected to be mostly affected and to have some general knowledge of the house.

Systems The kind of questions to the participants had to do with the heating/cooling system, the kind of energy (alternative or “on grid”) used, the kind of ventilation strategies they follow, if there are fans in toilets and kitchen, and what size of windows is used for each of the orientations.

Problems This section was devoted to finding out the problems in their structure that could affect the indoor climate. Common problems are reported in the literature and many self-organized forums as for instance the small overhang problem that can lead to cracked or washed out plaster. This section is used to examine the frequency in which these problems occur, and how they affect the inhabitants.

Finally, this section proposes solutions/advice on the reported problems before, during or after the construction process.

Indoor environment The study period was chosen to be either during the summer or during the winter. This choice is based on the global character of this research. Participants were asked questions such as how do they feel in the houses regarding indoor temperature, draught, indoor air quality, and how much time do they spend indoors. Last but not least the owners were asked if they had symptoms like fatigue, headaches, itching/irritated eyes or nose. The answers were examined to find out whether the symptoms are building related or not.

4.3 METHOD 4.3.1

CLIMATE ZONES SEPARATION

As first step, the dataset was separated in accordance to the climate factors.

It should be noticed that most of the replies came from Europe. Therefore, Europe was separated in three zones: south, central and north zone. The fourth zone was Australia and New Zealand in the South hemisphere. The fifth zone was USA.   

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South Europe (Greece, Italy, Spain, Basque country) Central Europe (Austria, Germany, France, Czech republic, Belgium, Poland, Slovenia) North Europe (Denmark, Sweden, Norway, England, Lithuania, Ireland, Estonia)

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 

Australia & New Zealand (Western, South Australia, Queensland, North Island, Blue Mountains) USA (Arizona, Idaho, Colorado, New Mexico, Ontario, California)

4.3.2

ANALYSIS OF THE CATEGORIES

4.3.2.1 Building features and Systems The two first categories, Building features, and Systems were analyzed in percentages.

As first to observe was the kind of the occupants’ habits, energy strategies, and building considerations.

4.3.2.2 Problems The participants in this section were able to report any structural problems and to comment on those.

Questions were related to walls and floors of the structure.

They were asked to describe general structural problems and to report which walls (depending the orientation) present most of the problems. Moreover, their response were checked if the problems were associated with the dominant wind and the lack of overhang.

Problems on the external walls, either on the outer or the inner side, such as cracks and mold propagation were of great importance. Moreover, more specific questions were asked related to the cracks close to the timber frame and their orientation (horizontal or vertical). Here the aim was to spot whether the cracks were dependent on the timber expansion and shrinkage. Expansion and shrinkage on the wood happens either naturally or forced. Forced expansion occurs due to the presence of moisture that could not be released to the ambient.

Every section of questions related to cracks, mold, finishing, and the floor was followed by participants’ comments. Furthermore, notes were taken on the most frequent problems that tend to appear.

4.3.2.3 Indoor climate Firstly, quantitive analysis of the answers was made. Afterwards, the answers were dichotomized in a binary structure, where 0 and 1 are used for positive/negative, large/small frequency and so on.

Figure 30. Dichotomization process for indoor climate assessment

Overall and regional specific analysis were made in accordance with the percentages, median, prevalence and the building’s related symptoms.

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4.4 RESULTS 4.4.1

GENERAL

Background responder’s information Seventy-two responders completed the questionnaire. Sixty-seven of them owned a straw house while the rest five responses were from stone houses, hemp lime and woodchip clay techniques. The sixty-seven straw houses will continue to the analysis phase.

Table 3. Survey completion by visitors

Translated in:

Unique visitors

Collected responses

Completion

English German Lithuanian French

453 82 142 -

50 10 12 -

11% 12% 8% -

The response rate was very low to validate the questionnaire (Bryman, 2008). However, by “unique visitors” (Table 3) it does not mean that all of them were related to straw buildings. The promotion way was very broad, hence, the low response rate is not giving any validation information.

Survey collection by region 60% 40% 20%

43%

25%

10%

10%

10%

0% North Europe Central Europe South Europe

Australia & New Zealand

USA

Figure 31. Survey collection by region

Most of the people completing the questionnaire were between 40-50 years old, whereas between the ages 20-30 were only 3% (Figure 32). Among them 66% were male and 34% female.

3%

87% were owning straw bale houses and 7% light clay straw houses.

28%

49% of the participants were self-builders (with friends and volunteers) and 12% were hiring professional builders.

Age 6%

21%

>70

60-70

15% 27%

50-60

40-50

30-40

20-30

Figure 32. Age of responders

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Table 4. Who built it in region

Who built it Self-built By professionals By supervision of professionals

North Europe

Central Europe

South Europe

66% 0%

24% 29%

57% 0%

Australia & New Zealand 29% 29%

34%

47%

43%

43%

From Table 4 it can be observed that professionals are mostly not preferred in North and South Europe.

In Central Europe, however, it seems that people are more evenly distributed between the self-builders and professionals. This may be a result of the effect of stronger associations in the field. Workshops were given to the public aiming to a cultural acceptance. Moreover, universities (e.g., in Kassel, Vienna and Munich) started research in this field.

USA 57% 14% 29%

Who built it - Global 39%

49%

12% Self build By professionals By supervision of professionals Figure 33. Who built it.

For the question â&#x20AC;&#x153;Is electricity partly or totally coming from an alternative energy system?â&#x20AC;? 37% responded positively while at the same question concerning alternative heating the positive responses were 60% (Figure 34).

Alternative Electricity & Heating - Global alternative electricity system alternative heating system

South Europeans seem to have the highest percentages of alternative energy dependence.

100%

37%

60%

0% 1 Figure 34. Alternative Electricity and Heating Table 5. Alternative energy usage in region.

Alternative Energy North Europe

21% 55%

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Australia & New Zealand Partly or total reliance on alternative electricity system 47% 71% 57% Partly or total reliance on alternative heating system 65% 71% 71% Central Europe

South Europe

USA

29% 43%

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Regarding the problems that arose while people were living for longer periods in their houses, 43% said that no problems were encountered while the rest 57% said that they had minor to larger problems.

These problems are usually cracks, molds or washed out stucco on the external walls (either on the outer or the inner side).(Table 6) Table 6. Problems reported by region

No Yes

Reported problems North Europe Central Europe South Europe Australia & New Zealand 57% 35% 47% 29% 65% 53% 71% 43%

USA 57% 43%

When Table 4 (who built it) is compared to Table 6 (reported problems), it can be seen that South and North Europe come first in the reported problems while in both cases the structures are not been built by professionals.

4.4.1

BUILDING FEATURES

Fig. 35 shows that timber frame was the most popular whereas strawbale loadbearing type houses were 12%. These results include all regionsThis distribution would be not for the south Europe since these regions are affected by earthquakes and have stricter building regulations.

Although in dry regions was expected to have used more earth/clay and in wet climates more lime.

49% of the participants use earth/clay as stucco material whereas 36% use lime. This results are spatially robust. (Fig 36)

1% 0%

Frame - Global

12%

84%

wood

steel

concrete

Figure 35. Frame material

External wall's stucco Global

For the internal stucco (Fig. 37) earth/clay is a preferable option (82%), whereas lime followed (10%).

The role of vapor diffusion of external walls in order to avoid condensation is worth mentioning. During the heating seasons where roomâ&#x20AC;&#x2122;s temperature is higher than the outdoors, condensation is very likely to form if vapor diffusion is not taken into account. Different temperature is, in fact, pressure difference and naure tends to equalize the pressure inside with the one outdoors. This process is called diffusion. Due to vapor pressure gradient, the water vapor in the air will find its way towards outside through the wall systems.

loadbearing

6%

36% 49%

Concrete paste

Earth/clay

Lime

Figure 36. External wall's stucco material

3%

Internal wall's stucco Global

10% 82%

1%

Earth/clay

Gypsum

Lime

Concrete paste

Figure 37. External wall finishing material

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Each material has a resistant to the diffusion of water vapor, the vapor diffusion coefficient (μ). μvalue is dependent on the density and the pore structure. Sd[m], the diffusion equivalent air layer thickness is the product of μ multiplied with the thickness of the respected material.

External wall finishing Global Lime paint 16% Waterglass 4% Linoil Nothing 7%

43%

The vapor diffusion resistance of the outer layer Figure 39. Internal wall's stucco material should be lower than that of the inside, moving from inside to outside it decreases. Earth/clay Vapor/Wind barrier renders present a relatively low μ-value of 6-8 in 6% comparison to cement’s μ-value that is 20-30. For Global a wall that consists of cement as the external Nothing, the plaster is doing the job stucco and earth/clay as the internal, the problem 12% Exterior wind barrier would be that the internal stucco should be significantly thicker than the outer. The vapor 78% Interior vapor resistance, in accordance with physical barrier calculations, should not exceed the value of 5m.

In the case of Sd exceeding the 5m, the potential Figure 38. Vapor and wind barriers humidity will be trapped inside the bales (Minke and Mahlke, 2005). From this relations, it can be concluded that when there is the application of different renders inside and outside it has to be taken into account the Sd-value. For instance, a common wall that consists of an external 3cm lime render (36% of the participants choice) and internally earth/clay render (82%) the later should have a thickness of more than 4,3cm.

It should be noted that a normal vapor barrier has an Sd-value of 10. Moreover, it is mentioned in the bibliography that linoil should be avoided as external finishing. The reason is the very high Sd-value of 1.45 of a single layer of linoil. According to the 4% of the people using it (Figure 38), it is reported that 3 layers were applied, which yield to the Sd-value of 4.35 solely without counting the thickness of the render. In fact, linoil blocks the porous structure of the render and it does not allow it to “breath”.

This will consequently trap moisture inside the wall, thus, create conditions for mold propagation.

Table 7. Wall insulation thickness in accordance with the region

Average (cm) min (cm) max (cm)

North Europe 45.2 20 55

Wall insulation thickness Central South Europe Europe 39.7 44 34 35 54 50

Australia & New Zealand 34.3 18 45

USA 24.3 20 30

13% of participants had flat roofs (Figure 41) even though most recommendations state of not designing flat roofs due to high risk of imperfections and potential water penetration, whereas 15% answered that is not having any overhang.

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Roof type- Global Pitched roof

13%

Roofing material - Global

1%

Metal

Flat roof

79%

10%

6%

Asphalt paper

27%

37%

Green roof Tiles

Barrel vault

15%

Plastic Figure 40. Roof materials

Figure 41. Roof type by type

Table 8. Roof insulation thickness by region

Average (cm) min (cm) max (cm)

North Europe 36.7 15 70

Roof insulation thickness Central South Europe Europe 36.5 23.5 23 5 50 50

30% answered that elevation from the ground was ranging between 0-20cm (Fig. 43). This is a very important parameter that should be taken more into consideration. Many studies (Minke and Mahlke, 2005 & Wihan J., 2007) suggest that the distance between the ground and the start of the wallâ&#x20AC;&#x2122;s render should be minimum equal to 30-35cm in order to protect the stucco from splashing water. Other ways to protect the stucco from the splash water include placing gravel and/or crushed stone bed, or low and dense vegetation at the perimeter. Rising damp can take place when the ground comes in contact with the stucco.

Australia & New Zealand 20.7 7 40

USA 37.6 20 75

Flooring - Global Earth/clay

10% 4%

Wood

21%

Tiles

36%

Concrete

Figure 42. Flooring

Elevation from the ground - Global 13% 9%

Some of the participants reported that usage of recycled materials, such as sea shells and broken glass bottles, have reduced the capillary action.

21% 48%

0cm

about 10-20cm

20cm-50cm

more less 1m

Figure 43. Wall's Elevation from the ground

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4.4.2

4% 13%

SYSTEMS

Ventilation system - Global

Heating system Global

10% 12%

10% 1%

18%

58% 75%

Wood burner Rocket stove (or similar) Gas Other Off grid Other On grid Figure 44. Heating system by type

Natural (windows-doors) Mechanical Hybrid Figure 45. Ventilation system

Fig 44 shows that 76% is using wood burner stoves. Among them 18% are using a more efficient solution, such as rocket stoves and bio mass ovens.

Table 9. Heating systems by region

Wood burner Rocket stove (or similar) Gas Other Off grid Other On grid Heat pump

North Europe 55%

Heating system Central South Europe Europe 59% 57%

Australia & New Zealand 43%

86%

USA

28%

6%

29%

14%

0%

0% 7% 21% 0%

0% 12% 6% 18%

14% 14% 0% 0%

0% 0% 29% 0%

0% 29% 0% 0%

Central Europe is the only region where 18% of the participants are using heat pumps whereas in the USA 86% uses wood burners.

Cooling is mainly achieved by natural ventilation (33% during the night).

Ventilation comes naturally (75%) or mechanically (22%). (Fig. 45)

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4.4.3

INDOOR CLIMATE

Indoor air quality (IAQ) was the most significant outcome. Participants had to choose between “excellent”, “fine” and “stuffy”. “fine” and “stuffy” present the same outcome. Since there was only one answer for “stuffy”, analysis uses “fine” and “excellent”.

One very important question deals with the indoor air quality during winter and summer. The possible answers were “excellent”, “fine” or “stuffy”.

Considering that the occupants built the houses themselves, it was expected that this fact could lead them to give biased answers in favor of “excellent” and “fine”. As it can be seen in Figure 46 and 47 the answers given agree with the previous hypothesis. The aim of the question was to figure out whether their perception regarding the IAQ could be affected by their habits during this period, by the chosen systems or by the building features.

Indoor Air Quality Summer 1% Excellent

21%

Fine 78%

Stuffy

Figure 46. Indoor air quality in summer

Indoor Air Quality - Winter 1% Excellent Fine

19% 79%

Stuffy

Figure 47. Indoor air quality in winter

Figures 46 & 47 show that 20% of the people perceived IAQ as “fine”. Parameters such as temperature, draft, structural-moisture problems, systems and ventilation habits, were assessed in order to find out whether there was correlation among them.

Moisture, structural problems and systems found not to be correlated with each others and were discarded from this analysis.

The next parameter to be discarded was temperature. Too low/high temperature but also varying temperature was found not to play any role on the perception of the IAQ as “fine”.

Ventilation habits were further analyzed. There were two questions in each season related to ventilation habits. 



33

How many times a day do you open the windows (approximate estimation)? o 1 o 2 o 3 o 4 o More than 5 How much time do you keep the windows open every time (approximate estimation)? o Less than 2 minutes o Less than 5 minutes o More than 5 minutes

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After the dichotomization process, 1 and 2 times of opening the window were assigned to “0” and the rest to “1”. Regarding the duration of each time, “Less than 2 minutes” was decided to correspond to “0” and the other two options to “1”.

The next step was to sum up those two questions. When the result was zero then the corresponding text indicates “low ventilation”, when the result was 1, the text indicates “medium ventilation” and when the result is 2 the text indicates “high ventilation”.

When this was set, the correlation between “fine” and “ventilation habits” could take place.

Table 10 summarises air quality perception and the associated ventilation habits.

Table 10. Indoor Air Quality perception and associated to ventilation habits

Summer. Associating "fine IAQ" with ventilation habits

Winter. Associating "fine IAQ" with ventilation habits

People perceived "fine" IAQ

21%

19%

Providing “High ventilation”

29%

13%

Providing “Medium ventilation” Providing “Low ventilation”

57% 14%

47% 40%

During the winter, ventilation needs to be improved in order to have better indoor air quality. 87% of the participants, who stated “fine” IAQ did not provide adequate ventilation. Whilst during the summer, the same parameter corresponded to 71% of the participants.

The chi square test (Siegel S.,1956) was used to identify if there was a relationship between “Low ventilation” and “Fine”. The test was particularly used for the winter period. The test showeded that 0.02 > than the significance level (0.05) and, therefore, the null hypothesis cannot be accepted. Thus, it is concluded that there is a potential relationship between “Low ventilation” and “Fine”.

According to the given answers, no building related prevalence was detected (1%max). (Table 11) Median 1 refers to people stating that they “never” had the aforementioned symptom. Whilst Median 2 refers to “sometimes (weekly)”, Median 3 to “often (weekly)” and finally Median 4 to “daily”. It is worth mentioning that participants stating to have the symptom “fatigue” and “headache” often, daily or sometimes, report in the comments section that it is due to other reasons like “young children (bad nights), hours of computer work” or “symptoms related to multi-allergies”.

Table 11. Building related problems

Symptoms

Fatigue?

Headache?

Itching, burning or irritation in eyes?

Irritated, stuffy or running nose?

Dry or itchy skin?

Prevalence

16%

4%

0%

0%

0%

1%

0%

0%

0%

1%

1

1

1

1

1

Building related prevalence Median

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4.4.4

PROBLEMS

In this section, presence of mold was mainly assessed in relation to the wind driven rain. Although, Wihan, J. (2007) concludes that the rain driven water will dry out before the start of straw decomposition, the analisys shows correlation to problems and hence increased need of buildingâ&#x20AC;&#x2122;s maintenance. The 57% of the reported problems were either minor, like small cracks, or more severe, such as mold on walls, vertical and horizontal cracks and washed out stucco.

The first taking into account, was the problems been reported on the wall affected by the dominant winds. It was found that 28% of the total number of participants reported that they did not have any overhangs or the overhangs were not properly oriented towards the direction of the dominant winds.

Thereinafter, it was found that among the 28% of those reporting lack of overhangs, a significant 42% reported problems on the plaster (cracks and molds)(Table 12).

Whilst, those who said that they had overhangs and that problems occurred only on the wall orientated to the dominant wind direction were assumed to have a relatively small overhangs. This group was found to consist of 16% of the total responders.

Table 12. Percentage of problems identified in accordance to small or lack of overhang

Percentage

Lack of protected wind driven Problems found where rain? (no overhangs where lack of protection against dominant winds are coming) wind driven rain 28% 42%

Moreover, 42% of the total responders reported horizontal cracks and 22% vertical cracks respectively. 30% of the total reported cracks near the timber frame and 19% reported washed or pealed out finishing of the external part of the walls.

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4.5 IMPROVEMENTS After many reported problems and due to the significantly large percentage of self-builders, it was decided to use this section in order to find practical and simple solutions for them in order to reduce the needed maintenance of their houses.

Breathable walls (wet climates) Materials like linoil that block the pores of the plaster should be avoided. The accumulated moisture, which can be caused by different reasons such as vapor pressure, will not be able to dry out and that could lead to cracks.

Breathable (vapor permeable) materials on the exterior façade, such as lime are preferable. This will effectively provide a coating on the wall that will not allow water to come in. At the same time, moisture from the wall can escape out. This issue is described in depth in chapter 5.4.2.

Another suggestion could be to use glass water (sodium silicate) coating on the last layer of the plaster.

Another suggestion could be to use glass water (sodium silicate) coating on the last layer of the plaster. This option is more suitable in cases of wind driven rain and does not affect permeability but repels water away.

Clay is permeable and hydrophilic material. Its property allows water to be absorbed and stored in it.

These characteristics work well for keeping moisture away from timber frame and straw. However, it needs an egress for taking out the water. For instance, if for any reason water penetrates into the straw, clay will absorb it and release it to the environment. If the exterior stucco is made of a material that does not allow the porous to breathe, the moisture will be trapped inside and crack the stucco or form mold on the wall.

Straw bale compression It is obvious enough that when the compression in uneven, the stucco does behave the same and cracks. Pay attention on having the same compression at least on the same wall if not everywhere.

Overhang Many people reported of having small overhang, having realized this only after their first year living in the new house. This seems to be a very common mistake probably because the overhang is mainly perceived as simply being a shading element.

It is extremely important for the overhang to have adequate length. This will keep the wind driven rain away from the biggest part of the wall.

In what follows, simple methods will be presented in order to estimate overhangâ&#x20AC;&#x2122;s adequate length.

First of all, overhang can be defined as an effective shading element. So the first step is to find out the proper length in order to keep the building protected from the sun in warm summer days (avoid overheating problems) and at the same time to allow the light to get in during the winter.

1. By visiting http://www.sunearthtools.com/dp/tools/pos_sun.php#chartP one can find out the angle of sunâ&#x20AC;&#x2122;s rays from the first to the last day of the summer period when the building have to be protected from overheating.

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2. For example, for a house that is going to be built in Spain it is necessary to keep the sun out from June- August. In the first of June at 12:00 the sun has an angle of approximately 66° of the sun’s elevation above the horizon and in August, 30 at the same hour sun’s elevation is 57°.

3. The selection of the lowest angle will automatically cover all the higher angles. In this example, this would be the 57° angle.

4. A simple sketch of the window wall helps in a significant way.

First a line starting from the bottom of the window (B point) and having the found degrees (57 degrees) has to be drawn. Afterwards, the overhang extends from the top of the wall to the line (A point). For this example an overhang of 1.23m could help to avoid overheating in the summer and also allow direct light to penetrate during the winter (all angles below 57°).

This particular overhang can keep the wind Figure 48. Sketch used to calculate the overhang's driven rain of a certain wind speed, only close to length the bottom of the wall the rain will fall.

From the questionnaire is quite evident that almost all the participants knew the dominant wind’s direction. This is an important information that can solve a lot of problems. It is essential to protect the wall from the wind driven rain that will come with pressure and cause problems to stucco by washing it out and cracking it. In that way, mold propagation can start in the straw or on the timber frame. Therefore, the wall that is exposed to the dominant winds should be dealt with extra care. The overhang over that wall should be longer than the designed shutter. 10-20% extension could be added to it as a minimum. It is a good idea to find out whether the new extended overhang blocks the sun rays that can warm the house during the winter.

Let’s see that on the same example. With 20% increased overhang this should be 1.48m in length.

This covers angles more than 48.5 degrees and will block sun’s rays from the first of April (before the spring equinox when sun’s elevation is 50 degrees above the horizon). This design protects the wall against wind driven rain. On the other hand, useful warmth could be lost during spring. Hence, it is essential to be critical of what is needed and what can be sacrificed.

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Rain screens Perhaps another suggestion for those who suffer from wind-driven-rain is to cover the affected wall with rain screens. In this way, the overhang can have a smaller length (it is not suggested to remove it completely).

Rain screens can be made out of many different materials. Important here is to maintain a ventilated cavity between the plaster and the rain screen and let the plaster breathe. A good advice here is to place the studs in a way that air can freely circulate behind the screens as shown in the Figure 49.

Figure 49. Rain screens placed.

Air can freely circulate.

Windowsills Some of the participants reported problems with their windows.

Mark from Colorado stated: “After 8 years there is some water degradation of the earth plaster under each lower corner of the windows apparently due to water dripping off the windows.”

It is always a good idea to take special care with the detailing of the windows. Not well placed windows and doors lead up to thermal Figure 50. Upper window flashing bridges. Thermal bridges can cause huge heat loses and affect the energy consumption and indoor environment even in houses with extra insulated walls. Installing a proper flashing over and under the window frame will effectively reduce potential reasons for cracks and mold propagation.

People also reported cracks on the stucco close to the window sills. This may be due to short overhang, lack of flashing, or as few people reported during the construction, because of gaps filling with stucco instead of straw.  Installing with care windows and doors and designing the details will reduce significantly thermal bridges.  Installing flashings over and under window frames (Fig. 50).  Filling the gaps with straw instead of render.

Wood burners Another important issue to address is the fact that wood burners need to be regularly and properly maintained.

According to the questionnaire, 80% of the participants are using wood burners, rocket stoves or something similar to heat their space, whilst only a 10% is using “on-grid” sources (Fig. 44). Poorly constructed or maintained wood stoves lead to poor indoor environment and can cause severe health problems. It is important to know the quality of the wood and its origin.

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PAQ experiment on clay plaster and painted gypsum board

5 PAQ EXPERIMENT ON CLAY PLASTER AND PAINTED GYPSUM BOARD A study by (Darling et al. 2012) has shown that clay plaster can actively reduce indoor ozone levels and result in a better indoor air quality (IAQ). Unfortunately, there is a lack of studies on other pollutants and the effect on IAQ by clay in general. Numerous studies have shown the hazards of thirdhand smoking (THS) (Matt et al. 2011) with the emphasis on carcinogenic compounds (RamĂ­rez et al.

2014). However, in some countries, e.g. Greece, smoking indoors is still a very common tradition.

During the authorsâ&#x20AC;&#x2122; stay in the measured straw and clay house in Crete, the occupants were occasionally smoking indoors. However, after the smoke was removed by natural ventilation, the smoky or other strong unpleasant odor could not be observed anymore. As clay plaster is a porous material, it should adsorb various gasses produced during smoking to the surface and cause thirdhand smoking (THS) by reemitting pollutants to the environment afterwards. This leads to a hypothesis that clay plaster might be adsorbing various chemicals of tobacco smoke and reemitting different THS pollutants from the usual THS tracers (Singer et al. 2002) or doing it at lower rates. In addition, the plaster might have a positive effect on IAQ after an exposure to smoke. A simple experiment on perceived air quality (PAQ) was planned. Conventional internal finishing of a painted gypsum board and a clay plaster were compared after exposure to smoke as well as without the exposure.

5.1 MATERIALS AND METHOD Four specimens were prepared for the experiment. Two painted gypsum boards and two clay plastered OSB boards. One of each kind was exposed to smoke in a public location in Copenhagen.

5.1.1

CHAMBERS

Four glass chambers were used in the experiment. Each consists of a glass structure, metal rack for hanging specimens, two metal meshes for filtering air and a plastic fan. All materials used inside were chosen to have no or a very low adsorbance to the surfaces. The chambers are constructed in a way that the fan sucks the air from the outside through a hole in the top lid and blows it through the volume where specimens are hung on the rack. Afterwards, it goes out of the chamber through a cone on the other side of the intake hole. Since the chamber is not perfectly airtight, some of the air might be recirculating inside the chamber, but it was assumed as a negligible value. The airflow is regulated by the speed of the fan and an adjustable area of the intake hole. During the experiment, the chambers were covered with an opaque material to hide specimens from the panelists.

Figure 51. The glass chamber with a clay plaster specimen.

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PAQ experiment on clay plaster and painted gypsum board

The air velocities were measured in the middle top of the cone by an anemometer and recalculated to an airflow. The standard airflow for evaluating IAQ from the cone is around 1 l/s, but all the chambers were set to 1,5 l/s rate based on observations during a test run. This ensured that the intensity of the odors reaching the nose was high enough to identify them. The chosen velocity is considered not to have a significant difference on PAQ due to the cooling effect in the nose.

All the glass chambers were put in one room with a ventilation rate of 2,95 h-1. During the experiment, the temperature of the air inside was kept constant at 20 °C. 5.1.2

SPECIMENS

The aim was to imitate the finish of an internal wall. The actual specimens’ size was determined by the size of glass chambers – 30x70 cm. The surface area of the one-sided plate was calculated to be a representative area in the chamber of four actual walls in a 5x5x3 m room. The other side of the board was covered with an aluminum tape without any VOC emissions and specially designed not to emit any smell.

Painted gypsum board Gyprock ERGO 13mm gypsum boards were used for the base of the specimens. They were painted with the acrylic water-borne “Lady Pure Color” paint from JOTUM, which is currently one of the most popular paints for interior surfaces on the Danish market. Prior to the painting, a primer was applied to the boards. Afterwards, they were painted with two paint coats as described in the manual and left to dry out for a few days.

Clay plaster 12 mm OSB boards were used for the base. A plastic net with the mesh size of 2 mm was then attached to the boards with staples in order to create an adhering surface for the clay mixture. First the clay plaster mixture was made of two parts sand, one part clay and one part of chopped straw (2-5 cm long). Note: clay and sand parts are expressed by mass and straw - by volume (not compressed). 2-4 mm sea sand was used. The clay was bought from a local distributor and the chemical composition of it is shown it Table 13: Table 13. Chemical composition of the clay used in the experiment.

Of total mass, %

SiO2 66,86

TiO2 1,13

Al2O3 18,71

Fe2O3 3,77

CaO 6,45

MgO 0,47

K2O 2,48

Na2O 0,13

GV 9,87

The clay and the sand were mixed in a dry form. Afterwards, water and straw were added until the desired consistency was reached – mixture is easy to stir, but it does not drip down while kept vertically on spatula in thickness of 2-3 cm. The mix was applied on both boards with the layer thickness of 1-1,5 cm. The sticking out straws were cut and fingerprints all over the surface were left intentionally to increase the adherence of the next layer. The specimens were dried in an industrial oven at 45 °C until its weight was not decreasing anymore.

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PAQ experiment on clay plaster and painted gypsum board

The second layer of the plaster consisted of three parts of sand, one part of clay and 0,1 part of fine straw (all by mass). 1 mm fine sea sand and the same clay was used. The fine straw was prepared by drying out horse manure and sifting it through a 1 mm metal net. All the components were mixed while dry. Afterwards, water was added to reach a proper consistency, which was more watery than the first one and was not sticking to a vertical spatula anymore. Before applying the second coat, the surface of the dried first coat was moistened to become soft again and diagonal strips were incised additionally. The thickness of the final layer was around 0,5-1 cm. Specimens were dried in the oven at 25 °C until the mass was constant.

Figure 52. Clay plaster specimens: OSB base with first (left) and second (right) layer.

5.1.3

EXPOSURE

Two specimens, one of each kind, were left in a normally-ventilated room without any specific odor for two weeks prior to the experiment. The other two were brought to a public bar, where customers were allowed to smoke inside and the ventilation system is not capable of removing the smoke. No measurements were done, but concentration levels of smoke were expected to be very high as â&#x20AC;&#x153;smoke mistâ&#x20AC;? is not a rare phenomenon in the place. The specimens were placed on the top shelves behind the bar to be protected from any unwanted contamination or damage. The bar has usual opening hours from 14:00 to 08:00. Firstly, the specimens were left at the bar for three days and taken away for a test. After a few days, they were returned to the bar for five more days. A study by (Singer, Hodgson, and Nazaroff 2003) has shown that stable levels of concentration of THS tracers in a fully furnished room (painted gypsum wallboards, 10 cigarettes a day during a 3 hours period in a 50 m3, 0.6 h-1 air change) are reached within seven days. Therefore, the exposure time in the bar was assumed to be enough to reach the maximum adsorption on the specimens. The back part of the gypsum and OSB boards were not covered during the exposure. For the transportation, specimens were packed with an odor-free plastic food foil to ensure airtightness. The experiment with panelists started within 12 hours from the time the specimens were removed from the bar.

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PAQ experiment on clay plaster and painted gypsum board

5.2 EXPERIMENTAL PROTOCOL The samples exposed to smoke were taken from the bar 12 hours before the experiment, but were kept sealed in the plastic foil until the start. After the wrapping was removed, the back sides of the boards were taped with odor-free tape, hung on the racks and put inside the chambers. Together with the specimens chambers were ventilated for 2,5 hours with the same ventilation rate of 21,6 h-1 used during the whole experiment. The panelists were shortly introduced to an IAQ evaluation questionnaire, instructed to take the breath directly from the top of the cones and randomly assigned to one of four chambers to begin with. After the first assessment, the order was chosen freely by the participants. To refresh the senses panelists had to walk to a neighbouring room with an open window after every evaluated chamber, so four times in total. 20 people participated in the experiment during the time period of 2 hours. No more than three participants were in the room at the same time.

5.2.1

QUESTIONNAIRE

The panelists had to answer a small questionnaire for each sample. It consisted of questions evaluating PAQ by acceptability scale, odor intensity, irritation in the nose and odor origin. Acceptability scale was set from -1 (clearly unacceptable) to +1 (clearly acceptable), odor intensity from 0 (no odor) to 1 (overpowering odor), and irritation from 0 (no irritation) to 1 (overpowering irritation). The panelists were asked to identify the odor from five suggestions evaluating the intensity from 1 to 5 (0, if none).

It was allowed to choose multiple answers with representative intensities if the origin of the odor was not clear. The questionnaire can be found in Appendix B. 5.2.2

PANELISTS

Participants were all volunteers – students or employees from DTU. Half of the panelists had the knowledge about IAQ experiments in general and the other half had no experience. Six of them were smokers and 14 non-smokers. There was not equal distribution in gender as well – 17 male and 3 female responders. Only one panelist was above the age of 35.

5.3 RESULTS AND DISCUSSION The specimens were given codes as follows: clay – C, gypsum – G, exposed to smoke – 1, not exposed to smoke – 0. The comparison was made between two pairs exposed and not exposed to smoke.

Results of each separate parameter are given in Figure 53. For a better comparison between the clay plaster and painted gypsum, pairs of two specimens with the same exposure assessed by the same panelist were analyzed. To validate the results a statistical non-parametric two-tailed Wilcoxon signed rank test (Woolson, R. F. 2008) was performed, as the results were not normally distributed.

Detailed answers for acceptability of air quality, odor intensity and irritation in the nose parameters can be found in Appendix B.

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PAQ experiment on clay plaster and painted gypsum board

5.3.1

PAQ ACCEPTABILITY, ODOR INTENSITY AND IRRITATION IN THE NOSE

Results are given in Figure 53. According to the median value, the exposed clay (C1) was less acceptable than the exposed painted gypsum (G1). The mean value shows slightly opposite results and is caused by a few very positive evaluations of the clay specimen. The range of answers about clay was noticeable higher. However, statistically, there was no significant difference found between the two. Odor intensity was slightly higher for the clay plaster and slightly lower for irritation evaluation.

Again, no statistically significant difference was found.

Unexposed clay (C0) had an identical evaluation for acceptability compared to the painted gypsum (G0) specimen with a slightly higher mean value. The clay plaster was evaluated to have a lower odor intensity. Very low irritation levels were reported and were identical for the two. No statistically significant difference was found between the compared samples.

The collected results show that the evaluation range for the clay plaster in all three parameters was wider than for the painted gypsum. The panelists had a more extreme evaluation on the less common material.

Overpowering odor/ irritation

Clearly 1 acceptable

0.8 0.6 0.4 0.2 No odor/ irritation

0 -0.2 -0.4 -0.6 -0.8 Clearly -1 unacceptable

Mean value C1

G1

C0

Acceptability

G0

C1

G1

C0

Intensity

G0

C1

G1

C0

G0

Irritation

Figure 53. PAQ evaluation results of painted gypsum and clay plaster on acceptability, odor intensity and nose irritation.

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PAQ experiment on clay plaster and painted gypsum board

1.4 1.2 1 0.8

C1 - G1/C0 - G0

0.6 0.4 0.2 0 -0.2 -0.4 -0.6

-0.8 -1 -1.2 Median

-1.4 Acceptability

Intensity

Irritation

Acceptability

Intensity

C1>G1

Irritation

C0>G0

Figure 54. Paired comparison of painted gypsum and clay plaster on acceptability, odor intensity and nose irritation.

Positive values indicate hypothesis C1>G1 and C0>G0 is true.

The assessmentsâ&#x20AC;&#x2122; values of the painted gypsum samples were subtracted from the clay plasters, hence positive results in the graph show that the clay plasters had a higher evaluation and the numbers indicate the difference in Figure 54. None of the results have passed the statistical test to prove a significant difference between the compared samples (Table 14). Especially for the acceptability parameter, where very wide whiskers can be seen in the graph.

However, some trends can be noticed. The identical intensity rating for C1 and G1 suggests, that the levels ensured an equal comparison. For both, exposed and not exposed to smoke cases, the clay plaster performed slightly better. For the unexposed case, higher odor intensity levels for painted gypsum suggest, that the clay plasters had a more neutral odor. Slightly higher irritation values for the clay plaster in smoke-exposed case, cannot be explained by the possible higher dust or other organic compounds as the irritation levels for the unexposed case are identical to the painted gypsum sample.

Table 14. Wilcoxon signed rank test (Woolson, R. F. 2008) results for C1=G1 and C0=G0 hypotheses.

T T-crit p-value alpha Conclusion

44

Acceptability 79 47 0.40 0.05 TRUE

C1=G1 Intensity 68.5 41 0.36 0.05 TRUE

Irritation 75 41 0.48 0.05 TRUE

Acceptability 75.5 53 0.22 0.05 TRUE

C0=G0 Intensity 36.5 30 0.09 0.05 TRUE

Irritation 66 35 0.47 0.05 TRUE

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PAQ experiment on clay plaster and painted gypsum board

5.3.2

ORIGIN OF THE ODOR

The participants could not correctly identify the prevailing origin of the odor for all the samples with the exception of the smoke-exposed painted gypsum board, which was very clear. The exposed clay sample did not have a clearly recognizable odor. It suggests, that adsorbed compounds from tobacco smoke might react with the clay and be reemitted to the environment as different compounds with a different overall odor. Alternatively, the natural odor of clay is overwhelming the odor of tobacco smoke adsorbed on the surface of clay, although results show that intensity level for the unexposed clay plaster was lower.

Dust

Organic

Plastic

Tobacco

Paint

5.00 4.50 4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 C1

G1

C0

G0

Figure 55. Origin of the odor.

5.3.3

DISCUSSION

The chosen time period for venting the specimens before the experiment ensured odor intensities, for an equal comparison, however, after the experiment it was observed that intensity levels were changing at a different rate. 24 hours after the experiment with a continuous ventilation C1 sample had noticeably lower intensity than G1, where tobacco odor was still clearly present. After 48 hours it was almost intangible while the clay sample had slightly higher odor intensity and would result in a lower acceptability rating. Further experiments should include more assessments during different time steps after the last exposure to smoke. Also, more kinds of clay should be examined, especially the ones that are claimed for air purification. In order to have a full picture, besides PAQ a chemical analysis of the reemitted THS compounds must be carried out simultaneously.

5.3.4

CONCLUSIONS

None of the acceptability, intensity and irritation parameters passeed the statistical test to prove a significant difference between the two compared samples in both, exposed and not exposed to smoke, cases. Assessment of the odor origin confirmed initial observations that after continuous exposure to smoke the odor of the clay plaster, caused by secondary THS pollutants, cannot be recognized as a typical THS odor. It may suggest that byproducts caused by chemical reactions with the clay might result in different chemical compounds, at least those that are odorous. However, a detailed chemical analysis must be carried out to confirm these speculations.

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Study cases in Crete

6 STUDY CASES IN CRETE Two study cases – a traditional Cretan stone house and a recently built straw light clay house – were chosen to be measured for thermal comfort conditions during a few summer and autumn months.

The first goal was to examine the straw house if it creates a satisfactory indoor climate and to determine what is the importance of internal clay plaster regulating relative humidity levels indoors.

Also, to see if the thermal mass of it helps to lower down temperature fluctuations. The second objective was to compare both houses in terms of thermal comfort during warmer and colder periods.

6.1 EVALUATION OF THERMAL COMFORT 6.1.1

CRITERIA

All the classifications in this section (6.1) refer to annual data and the labeling of any particular category are met when a specific parameter represents at least 95% of occupied hours in the room.

For both houses, all the hours were assumed to be occupied. Since the measurements lasted a few months during summer and autumn, the whole year is not represented, hence, labeling of a particular category cannot be done. Criteria described in the following sections are used only as guidelines for the evaluation.

Table 15. Description of the applicability of the categories (DS/EN 15251, Table 1).

6.1.2

TEMPERATURE

The Greek national standard (ΚENAK, 2010) for thermal comfort conditions recommends the temperature range between 20 °C and 26 °C for heating and cooling set points, without specifying any classes (KENAK, Table 2.2). Therefore, a more developed DS/EN 15251 standard was used. The thermal comfort was evaluated based on the two different models.

The prescriptive model is usually used for buildings with mechanical HVAC systems, however, the temperature ranges describing comfort conditions (Table 16) can be used to evaluate buildings ran by natural ventilation as well. The category ranges for the evaluation were taken from the low point for heating to the high point of cooling as occupants could heat up the place, freely choose how to operate ventilation through doors and windows and change their clothing level according to their comfort temperature.

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Study cases in Crete

Table 16. Temperature ranges of prescriptive model (DS/EN 15251 Table A.3).

The adaptive model is used for buildings with only natural ventilation. It takes into account the temperature differences between indoor temperature and running outdoor mean temperature. Other limitations included activity levels are between 1,0 and 1,3 met and occupants must be able to change their clothing level at least in a range of 0,5 - 1,0 clo, which is met by the investigated cases. The model is based on a study on naturally ventilated offices in different climates.

The daily running mean temperature was calculated by formula (2) for the first day and by formula (1) for the rest of the data points with recommended parameter Îą=0,8. This means that the weighted running mean takes into account the last seven days to predict the occupants adaptation to the outdoor temperature. Î&#x2DC;đ?&#x2018;&#x;đ?&#x2018;&#x161; = (1 â&#x2C6;&#x2019; đ?&#x203A;ź) â&#x2C6;&#x2122; Î&#x2DC;đ?&#x2018;&#x2019;đ?&#x2018;&#x2018;â&#x2C6;&#x2019;1 + đ?&#x203A;ź â&#x2C6;&#x2122; Î&#x2DC;đ?&#x2018;&#x;đ?&#x2018;&#x161;â&#x2C6;&#x2019;1

(1)

Where Î&#x2DC;đ?&#x2018;&#x;đ?&#x2018;&#x161; - running mean temperature for today Î&#x2DC;đ?&#x2018;&#x;đ?&#x2018;&#x161;â&#x2C6;&#x2019;1 - running mean temperature for previous day Î&#x2DC;đ?&#x2018;&#x2019;đ?&#x2018;&#x2018;â&#x2C6;&#x2019;1 â&#x20AC;&#x201C; daily mean external temperature for the previous Î&#x2DC;đ?&#x2018;&#x2019;đ?&#x2018;&#x2018;â&#x2C6;&#x2019;2 â&#x20AC;&#x201C; daily mean external temperature for the day before and so on

The following approximate equation can be used as well: Î&#x2DC;đ?&#x2018;&#x;đ?&#x2018;&#x161; = (Î&#x2DC;đ?&#x2018;&#x2019;đ?&#x2018;&#x2018;â&#x2C6;&#x2019;1 + 0,8 â&#x2C6;&#x2122; Î&#x2DC;đ?&#x2018;&#x2019;đ?&#x2018;&#x2018;â&#x2C6;&#x2019;2 + 0,6 â&#x2C6;&#x2122; Î&#x2DC;đ?&#x2018;&#x2019;đ?&#x2018;&#x2018;â&#x2C6;&#x2019;3 + 0,5 â&#x2C6;&#x2122; Î&#x2DC;đ?&#x2018;&#x2019;đ?&#x2018;&#x2018;â&#x2C6;&#x2019;4 + 0,4 â&#x2C6;&#x2122; Î&#x2DC;đ?&#x2018;&#x2019;đ?&#x2018;&#x2018;â&#x2C6;&#x2019;5 0,3 â&#x2C6;&#x2122; Î&#x2DC;đ?&#x2018;&#x2019;đ?&#x2018;&#x2018;â&#x2C6;&#x2019;6 + 0,2 â&#x2C6;&#x2122; Î&#x2DC;đ?&#x2018;&#x2019;đ?&#x2018;&#x2018;â&#x2C6;&#x2019;7 )/3,8

(2)

Categories were calculated by these formulas:

Where Î&#x2DC;đ?&#x2018;&#x2013; - limit value of indoor operative temperature, °C 47

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Study cases in Crete

In Figure 56 the darkest green represents category I, the middle green â&#x20AC;&#x201C; category II and the palest green â&#x20AC;&#x201C; category III. As no measurements of indoor air velocities were taken, it was assumed they were not higher than 0,18 m/s. The higher velocities would increase the upper temperature limit for all the classes.

Figure 56. Operative temperature ranges for three categories of the DS/EN 15251 adaptive thermal comfort model.

6.1.3

RELATIVE HUMIDITY

The Greek national standard (KENAK, 2010) propose to keep the average RH 40% in summer and 45% in winter, which is impossible to achieve in a warm and humid climate like Crete. Therefore, it is again evaluated according to DS/EN 15251 recommendations (Table 17). The standard is created for needs of design criteria if humidification and dehumidification systems are installed, but the ranges of relative humidity can be used as a general rule of thumb. The standard also recommends limiting the absolute humidity to 12 g/kg (mass of water vapor/mass of dry air).

Table 17. Recommended humidity levels in occupied spaces (DS/EN 15251, Table B.6)

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6.2 SPECIFICATION OF THE AREA Two study cases are located in Crete, Greece. It is the fifth largest island in the Mediterranean Sea 300 km from the African coastline. It has an elongated shape – 260 km from east to west and 60 km in the widest point from south to north. Crete is between two climatic zones – Mediterranean and North African, mainly the former one. In general, the climate is humid with mild winters and hot summers.

Snow is common during the winter season in upper mountain ranges and very rare in low ranges near the coastline.

Figure 57. Location of Archanes in Crete.

The exact location of the two houses is in the middle sized village of Archanes, 12 km from the Aegean sea in the north and 32 km from the Libian sea in the south. The village lies under an evening shadow from the Youchtas mountain with an altitude of 811 m from the west. The bigger part of Archanes is built on the east side of a valley, which runs along the mountain in the south-north direction, in a range of altitude from 350 m to 470 m. The mountain and the higher altitude is creating a specific micro-climate distinctive from the surrounding area. Temperature difference determined by the altitude (2-4 °C higher on the coast) and presence of the valley causes high local winds and high humidity levels. Warm moist air from lower ranges is transported to the lower temperature zone, where its relative humidity increases due to the lower water saturation pressure. During summer nights, when outdoor temperature fluctuations are high, the relative humidity sometimes reaches near 100 % levels. Dominant winds are from the north-west. Often very hot south winds are blowing from the coasts of Africa as well. During winter sub-zero temperatures and snow is expected for several weeks.

Figure 58. Average (24 hours mean) temperatures and precipitation in Archanes. [yr.no]

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Archanes is a traditional Cretan village with archeological history of the surrounding area dating back for around 5000 years. It is a prototype village, meaning traditional architecture, culture and lifestyle are promoted. Over 200 old buildings have been refurbished using the traditional building materials, techniques and colour ranges. Homogenous architectural style is preserved by a rule from the municipality that all new constructions must meet the requirements to at least look like the old fashioned buildings. A traditional house in Archanes is built from marly limestone, has medium sized windows and red ceramic tiles on the roof. The color palette of exterior finishes varies from darker tones of pastel yellow to red with brownish overtones with some exceptions of white lime finishes.

Figure 59. Archanes village from mountain Youchtas (picture by Author).

6.3 STUDY CASES 6.3.1

LIGHT STRAW CLAY HOUSE (LSC)

The house was built in 2013 by a self-builder and owner Jorgos Ritsakis with help of not professional volunteers. It is situated above the village at the altitude of 470 m in an open area surrounded by middle sized olive trees and bushes. Orientation is southwest â&#x20AC;&#x201C; northeast (for simplification S-N orientation is used in the report). The building is incorporated into a sloped terrain â&#x20AC;&#x201C; north and a part of east facade are facing a natural retaining wall.

Figure 60.Visual representation of LSC house in Archanes, Crete, Greece.

The house has a double timber-framed load-bearing structure for walls. Single-spanned timber joists carry a single-pitched tile roof on one half of the house and a flat roof on the other half of it. The external walls are insulated with 35 cm thick straw and clay mixture. The technique used is unique as the amount of clay in the mixture is very small, thus, the density of the infill of the walls does not fall within the range (400-1200 kg/m3) of typical straw and light clay houses (Minke and Mahlke, 2005).

Loose straw was rinsed with clayey water and not mixed with clay, which is the common way of doing it. An approximately 3 m long section of external wall facing south was built from adobe bricks (clay, mud and sand).

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Study cases in Crete

Three layers of clay plaster are used for internal and external walls. The internal side is lime-washed and exterior is finished with water-repellent linseed oil. The floor finishing is made from laminate and ceiling is covered by wooden boards. Southern side has 1 m wide overhang. All the double-pane windows and doors on the east and south side have external shutters except for the dining room, which was broken during a storm. The same case is also for the only window on the west side. There is a possibility to install a wood burner, but currently electric heaters are used when needed.

Figure 61. LSC house: top left – north façade, top right – south façade, middle – south façade and Mt. Youchtas and Archanes village in the valley, bottom – dining room.

The 72 m2 house was built with an intention to be a single floor, but as the ceiling height on the higher side of the pitched roof reaches 4.5 m, an additional floor was constructed above the kitchen. The open height of storage and WC rooms were lowered down to 2.3 m. The space above is used for storage purposes.

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Figure 62. LSC house: ground floor plan.

6.3.2

TRADITIONAL STONE HOUSE

The second building chosen for measurements is a traditional Cretan stone house, like the majority of the houses in Archanes. It is a two-story multi-pitched roof building with a roof terrace and is situated as well on the western side of the valley, but at the lower altitude of 390 m. Streets in the area are narrow, so neighboring buildings are very close and cause shadows. From the north and west, two streets are framing the building. Dwellings on the opposite side of the streets are no further away than 4 m, therefore, they drop a shadow on the east wall in the morning. The backyard is stretching in the west direction. The trees in the garden are around 3m tall and shadow the west side of the house in the afternoon, where the southern wall is connected to an adjacent building and is not exposed to outdoor conditions. All the windows are facing towards west, except one on the first floor facing east.

The ground floor gets direct sun very rarely, because of the trees in the garden and the Figure 63. Location of the STONE house in Archanes. evening shadow of the mountain.

The construction date is 1926, but the latest major renovation was made in 2002. No changes were made to the original 58 cm thick load-bearing limestone walls. On the first floor above the living room, a monolith concrete extension was built. A new traditional red ceramic tile roof was constructed over a wooden frame. The house was lime plastered and painted from outside and gypsum plastered from inside. The ground floor has a tiled flooring and the first floor has wooden boards. Windows and doors (partly glass) have a single pane glass and a timber frame and are installed with external shutters. Only the living room has a fireplace. During the winter additional temporary fire burner is installed in the living room as well. Other rooms are using electric heaters if needed.

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Figure 64. STONE house: left – backyard and the adjacent building from the south, right – living room.

The 44,6 m2 ground floor includes a living room joined with a kitchen, a bathroom and a guest bedroom with a ceiling height of 2,7 m. Owners bedroom, an unheated extension room with a rooftop terrace is situated on the first floor – 30 m2 in total.

Figure 65. STONE house: Ground floor plan.

Figure 66. STONE house: First floor plan.

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6.4 MEASUREMENTS 6.4.1

OVERVIEW

Temperature, relative humidity and CO2 concentration were continuously measured by a HOBO U12 Temperature/Relative Humidity/Light/External Data Logger and a Vaisala Carbocap Carbon Dioxide Transmitter Series GM20 device. The exact locations of placement indoors were determined by avoiding possible spots of draft, direct sunlight and a short distance to CO2 sources in bedrooms.

An open and freely ventilated shed was chosen for the outdoor placement of the loggers to protect from rain and direct sunlight. Three rooms were selected in each house – two bedrooms and one living room. One of the bedrooms was used by the owner(s) and the other one was used by guests in both cases.

The HOBO loggers are built to measure temperatures in a range of -20 °C to +70 °C with an accuracy of ±0,35 °C (range from 0 °C to 50 °C). The range for measured relative humidity is from 5% to 95% with an accuracy of ±2,5% (typical) from 10 % to 90 % to a maximum of ±3.5% (HOBO, 2016). Vaisala device can measure CO2 concentrations within a range of 0 to 20000 ppm with an accuracy of 2% (of range) + 2,0% (of reading) (Vaisala, 2015). All the loggers prior the measurements were calibrated for a range of 0 to 5000 ppm. Time step for recording data was set to 10 minutes. However later on in data analysis values for every 30 minutes was used.

The LSC house was measured from 11.08.2015 until 03.11.2015 and the STONE house from 20.09.2015 until 03.11.2015. During the second period, authors of this report were living in the LSC house and constantly observed occupants behavior and operation of the house.

6.4.2

DATA ANALYSIS

Besides the raw data analysis, absolute humidity, or the moisture content, was calculated by formula (14) (Vaisala, 2013). Absolute humidity expressed by this formula is know as the mixing ratio:

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Ambient atmosphere pressure (ptot) was calculated for both locations separately as the difference in altitude was 81m. ptot, LSC= 95804,74 Pa, ptot, LSC= 96738,32 Pa. Partial vapor pressure for water was calculated by formula (Carsten, 2013): đ?&#x2018;?đ?&#x2018;¤,đ?&#x2018; đ?&#x2018;&#x17D;đ?&#x2018;Ą (đ?&#x153;&#x192;) = 288.68 (1.098 +

đ?&#x153;&#x192; 8.02 ) 100

(3)

6.5 RESULTS The time series and the cumulative graphs are presenting results for CO2 concentration, temperature, relative and absolute humidity. Only fragments of time series graphs are used in the main report, but in order to have a full picture and higher scale of the graphs, the reader is advised to have Appendix D open. It as well contains all the cumulative graphs for the different time periods on one sheet for easier visual comparison.

First of all, the outdoor conditions and the measurement periods are overviewed and is followed by the CO2 concentration results. Afterwards, the first period when only LSC house was measured is presented and is continued by a period where both houses were measured at the same time. The analysis is based on a comparison between the two. In the end, an evaluation of thermal comfort is presented followed by conclusions of the measurements.

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50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10

OUTDOOR CONDITIONS

Cold period

LSC measurements start

STONE measurements start

Temperature

90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10

RH, %

Temperature, °C

6.5.1

RH%

Figure 67. Outdoor temperature and relative humidity during 11.08.2015 – 03.11.2015.

The whole time of measurements can be divided into three periods (Fig. 67). They are defined by the time when loggers were placed in the houses and different weather outdoor conditions. During the first period (11.08.2015 - 19.09.2015) only the LSC house was measured and very well represents typical hot Crete summer outdoor conditions. The second period (20.09 – 22.10), started when the loggers were placed in the STONE house. Outside the temperatures were lower and represent warm early autumn conditions. From this point, both houses are measured at the same time. The third period (23.10.2015 – 03.11.2015) stands out with a sudden fall of outdoor temperature, which stays stable with much lesser fluctuations between day and night for the last 10 days of the measurements. The last period represents autumn conditions.

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CO2 concentration, ppm

Study cases in Crete

1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0

Outdoor

LSC Living room

West bedroom

LSC East bedroom

CO2 concentration, ppm

Figure 68. CO2 concentration in LSC house during 11.08.2015 – 03.11.2015.

1100 1000 900 800 700 600 500 400 300 200 100 0

Outdoor

STONE Living room

STONE Bedroom upstairs

Figure 69. CO2 concentration in STONE house during 20.09.2015 – 03.11.2015.

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STONE Guest bedroom

Study cases in Crete

6.5.2

CO2 CONCENTRATION

There have been various data logging malfunctions in most of the rooms in both houses during the period of measurements. It can be seen in the graphs as concentration levels of 0 ppm. The outdoor CO2 concentration was measured starting only from 15.10 until 03.11 â&#x20AC;&#x201C; the end of measurements. It had been not possible to safely place the logger outside with a proper supply of electricity. The values in the rooms are real measurements without deduction of ambient concentration.

The occupancy schedule was very hard to define in the LSC house as people living there did not have a strict schedule. Most of the time during the warm period people were moving between indoors and outdoors leaving doors open with some longer periods of absence once a day. The presence of animals and their movement increased opening of doors and windows during the daytime. Most of the nights they were sleeping inside the house. One person was usually sleeping in each bedroom and in the living room. In the STONE house usually two people were sleeping in the bedroom upstairs.

Table 18. Occupancy, occupancy schedules, ventilation strategies for LSC and STONE houses.

Occupancy

Occupancy schedule LSC 2-4 adults All the time, 60% 3-4 middle in the house size dogs during warm 5 cats period, 80% during cold STONE 1-2 adults Mon-Sat 9:0017:00 not at home

Ventilation strategy warm period Doors and windows open during most of the day and night

Ventilation strategy cold period A small window always open in the bathroom. Doors and windows kept open for short periods during the day.

Closed at night Doors and windows 10 min cross ventilation in open when at home, upstairs bedroom few times closed on ground floor a day, closed everywhere when nobody is at home else.

Until 23.10, the outside temperatures were comfortable enough to have both windows and doors open all the time. The CO2 concentration measurements prove that during this period both houses were ventilated very well (Fig. 68, 69). During the last 10 days of the measurements, the temperature outside dropped significantly and the occupants had to change their ventilation strategies. The opening schedules of windows and doors changed to only short periods of time few times a day. Night ventilation was not used as occupants felt too cold and not adapted to the rapid change. This resulted in higher CO2 concentrations in all the rooms.

The concentration levels were always higher in the LSC, as the occupancy load was higher and most of the time they stayed in the house. In the LSC house concentrations in the living room were the highest among all the rooms as occupants were spending the most of the time in the area (Fig. 68).

While in the STONE house the bedroom upstairs, where two people were sleeping during the nights, had the highest values (Fig. 69). Big differences between the houses can be seen during the cold period. CO2 concentrations are much higher in the LSC house. This again can be explained by the occupancy â&#x20AC;&#x201C; there have been three people living in LSC and only one at the STONE at that time.

However, this might be caused by higher infiltration rates in the STONE house. Unfortunately, there are no measurements of the bedroom upstairs in the STONE house during this period.

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Study cases in Crete 6.5.3

MEASUREMENTS OF LSC DURING 11.08.2015 – 19.09.2015

The measurements in the LSC house started in the middle of the summer when the outdoor conditions were more extreme and it was harder to ensure desirable indoor thermal comfort.

Temperature, °C

Temperature 11.08 – 09.19 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 0

10

20

30

40

50

60

70

80

90

100

Cumulative frequency, % Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

Figure 70. Temperature in LSC house during 11.08 – 09.19.

The temperature differences between the three rooms are caused by their orientation and shading.

East bedroom gets sunshine only until the middle of the day and external shutters are closed almost all the time by occupants will. The living room has big windows oriented south and shutters on one of the two big door-windows are closed when occupants feel too warm inside. Also, this space is quite often cross ventilated. The west bedroom is exposed to the sun from the late morning until the sunset and in the time of measurements, there were no external shutters, only internal draperies. Figure 70 shows that the temperatures indoors, in general, are high – 70% of the time higher than 26 °C. Although, the thermal mass of the internal plaster is not great, it still accumulates heat and makes it more difficult to cool down the rooms during the night. The fact that the outdoor temperature is about 65% of the time lower than the temperature inside suggests that night ventilation is not used efficiently.

The relative humidity measurements (Fig. 71) show the opposite distribution of the least to most humid rooms in comparison with the coolest to warmest by temperature. It perfectly represents the RH% formula for constant moisture conditions. In general, relative humidity levels are quite acceptable – 20% of the time it is higher than 60% while outdoor levels are 45% of the time higher than this threshold.

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Relative humidity 11.08 – 09.19 85 80

Relative humidity , %

75 70 65 60 55 50 45 40

35 30 25 0

10

20

30

40

50

60

70

80

90

100

Cumulative frequency, % Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

Figure 71. Relative humidity in LSC house during 11.08 – 09.19.

The moisture content is very stable between the rooms (Fig. 72). It supports the inversely distributed temperature and relative humidity graphs. This graph also shows that the actual moisture content is higher than the outdoor measurement for 80% of the time. This means that there is a great source of moisture production indoors. As the temperatures inside are high most of the time, increased sweating rate for humans and higher moisture production from animals through respiratory system are expected.

Mixing ratio, g/kg

Moisture content 11.08 – 09.19 20 19 18 17 16 15 14 13 12 11 10 9 8 7 0

10

20

30

40

50

60

70

80

90

100

Cumulative frequency, % Outdoor

LSC West bedroom

LSC East bedroom

LSC Living room

Figure 72. Moisture content in LSC house during 11.08 – 09.19.

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COMPARISON OF LSC AND STONE DURING THE PERIOD OF 20.09.2015 – 03.11.2015

Temperature

Temperature 05.10 – 13.10 30

Temperature, °C

28

26 24 22 20 18 16

Outdoor

LSC Living room

West bedroom LSC West bedroom

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom Figure 73. Temperature in LSC and STONE houses during 05.10 – 13.10.

Temperature 20.10 – 28.10 28 26

Temperature, °C

24 22 20 18 16 14 12 10

Outdoor

LSC Living room

West bedroom LSC West bedroom

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom Figure 74. Temperature in LSC and STONE houses during 20.10 – 28.10.

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Study cases in Crete The STONE house has much more stable temperatures during the warm period (Fig. 73). Most likely due to the high thermal mass while the LSC experiences much greater fluctuations. However, temperatures in the LSC also stabilizes during the cold period (Fig. 74), because of the lower ventilation rates and insulated building envelope. In the STONE house, which has no insulation only the living room is equipped with a fireplace. In Figure 74 it can be seen that in the evening the fireplace was being used, but did not have an impact on the bedroom upstairs (the occupants reported that they had to use an electric blanket). During the cold period, the daily outdoor temperature fluctuations are not affecting the indoor temperatures at all.

Temperature, °C

Temperature measurements 20.09 – 03.11 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 0

10

20

30

40

50

60

70

80

90

100

Cumulative frequency, % Outdoor

LSC Living room

West bedroom LSC West bedroom

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom Figure 75. Temperature in LSC and STONE houses during 20.09 – 03.11.

From Figure 75 it can be seen that the temperatures, in general, are higher in LSC due to the insulation over the colder period and the high thermal mass in the STONE house, which kept temperatures lower during the warm period. The temperatures in the STONE are very similar in all the rooms during the warm period. During the cold one, it gets more scattered as rooms have different area of external surfaces, where heat due to conduction is “lost” to the outside. The more scattered lines of the STONE house indicate the cold period. A desirable trend of lower temperatures in the bedrooms can be noticed from the graphs. However, the occupants of the LSC house wanted higher temperatures.

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Study cases in Crete Relative humidity

Relative humidity 05.10 – 13.10 85

Relative humidity, %

80 75 70 65 60 55

50 45 40

Outdoor

LSC Living room

LSC West bedroom West bedroom

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom Figure 76. Relative humidity in LSC and STONE houses during 05.10 – 13.10.

Relative humidity 20.10 – 28.10 90

Relative humidity, %

85 80

75 70 65 60 55 50 45

Outdoor

LSC Living room

West bedroom LSC West bedroom

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom Figure 77. Relative humidity in LSC and STONE houses during 20.10 – 28.10.

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Study cases in Crete Most of the time, relative humidity is not fluctuating a lot in both houses, but sometimes follows the outdoor levels very closely (Fig. 76 11.10-12.10). This suggests that it was a significant change in the moisture content levels of the outdoor air as the outdoor temperature during that time was not fluctuating a lot. In the colder period (Fig. 77), the outdoor levels have an even lower impact on the indoor humidity. During the warmer period, there are more local fluctuations, which is not seen outdoors, than during the cold.

Relative humidity 20.09 â&#x20AC;&#x201C; 03.11 90 85

Relative humidity , %

80 75 70 65 60 55 50 45 40 0

10

20

30

40

50

60

70

80

90

100

Cumulative frequency, %

Outdoor LSC East bedroom STONE Guest bedroom

LSC Living room STONE Living room

LSC West bedroom West bedroom STONE Bedroom upstairs

Figure 78. Relative humidity in LSC and STONE houses during 20.09 â&#x20AC;&#x201C; 03.11.

Relative humidity is inversely proportional to the temperature of the air and can be clearly seen for the LSC house, where the warmest (living) room has the lowest RH% readings and vice versa for the coolest (west) room (Fig. 78). In general, relative humidity levels are high in both houses, but the outdoor levels are even higher for 70-90% of the time. Clay plaster failed to keep the levels around 50% as described in the literature. This suggests that moisture content in the humid climate was greater than the moisture absorption capacity of the clay. During the summer time, it is impossible and unpractical to try mechanically lowering indoor humidity levels as doors and windows are open all the time.

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Study cases in Crete Moisture content

Moisture content 05.10 – 13.10 16

Moisture content, g/kg

15 14 13 12 11 10 9 8 7

Outdoor

LSC Living room

West bedroom LSC West bedroom

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom Figure 79. Moisture content in LSC and STONE houses during 05.10 – 13.10.

Moisture content 20.10 - 28.10 14

Moisture content, g/kg

13 12 11 10 9 8 7 6

Outdoor

LSC Living room

West LSC bedroom West bedroom

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom Figure 80. Moisture content in LSC and STONE houses during 20.10 – 28.10.

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Study cases in Crete The absolute humidity takes into account both parameters – relative humidity and temperature.

Therefore, it is a more accurate parameter for tracking moisture rather than only RH%. The graphs show that the actual moisture content indoors is following the outdoor levels more than RH% graphs suggest. It is obvious for the 11.10-12.10 period (Fig. 79). All the small fluctuations give a hint of the local moisture production. For example, bedroom upstairs in the STONE house has always lower moisture content. As it is only occupied during the nights, it can be seen in the graphs that after midnight, the gap between this bedroom and other two rooms is always getting lower (Fig. 80).

Moisture content 20.09 - 03.11 17 16 15

Mixing ratio, g/kg

14 13 12 11 10 9 8

7 6 0

10

20

30

40

50

60

70

80

90

100

Cumulative frequency, %

Outdoor

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom

West bedroom LSC West bedroom

LSC East bedroom

LSC Living room Figure 81. Moisture content in LSC and STONE houses during 20.09 – 03.11.

The cumulative graph (Fig. 81) shows an interesting finding – the moisture content in all three rooms in the LSC house are almost identical for the most of the time. While, despite almost identical temperatures in the STONE house (except the cold period), moisture content levels are more scattered than for the LSC. This supports the hypothesis that clay plaster is actively affecting indoor moisture content levels. Higher absolute humidity indoors is caused by the higher temperatures kept inside, which can “hold” more water vapor than the colder outdoor air. In general, the levels are quite high.

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Study cases in Crete 6.5.5

EVALUATION OF THERMAL COMFORT IN LSC HOUSE DURING 11.08.2015 â&#x20AC;&#x201C; 19.09.2015

Thermal comfort was evaluated based on two different models, which gave very different results.

Results in presented in Sections 6.5.5 and 6.5.6 represents percentage of hours in specific categories.

Only occupied hours are taken into account.

Table 19. Amount of time within categories for temperature ranges in LSC house (prescriptive model).

Prescriptive model 11.08-19.09 (% of occupied hours) Temp range Living room West bedroom East bedroom Class I 21-25 3,4 8,8 7,6 Class II 20-26 19,9 14,8 21,9 Class III 18-27 29,4 21,8 30,3 Out of range 47,3 54,7 40,2 Table 20. Amount of time within categories for temperature ranges in LSC house (adaptive model).

Adaptive model 11.08-19.09 (% of occupied hours) Living room West bedroom East bedroom Class I 84,2 71,6 87,8 Class II 11,1 18,8 10,6 Class III 3,3 6,3 1,2 Out of range 1,4 3,3 0,4 The prescriptive model suggests that the thermal comfort in the LSC house during the summer was unacceptable and did not even classify for the lowest category â&#x20AC;&#x201C; it is too hot. The results show that the coolest East bedroom performs best, and the warmest West bedroom worst (Table 19).

The adaptive model gives the opposite results (Table 20). Most of the time the indoor temperatures were within the highest category. The reason for the conditions to be classified for lower categories is too low indoor temperatures in comparison with the outdoor running mean. The best performance is shown by the warmest East bedroom and the worst by the coolest West bedroom.

In fact, the occupants were not complaining of the high temperatures during the summer and adapted their expectations accordingly to the very hot ambient conditions.

Table 21. Amount of time within categories for relative humidity ranges in LSC house.

Relative humidity 11.08-19.09 (% of occupied hours) RH% Living room West bedroom East bedroom Class I 30-50 12,5 17,8 5,8 Class II 25-60 82,2 58,4 66,3 Class III 20-70 5,3 23,8 27,9 Out of range 0,0 0,0 0,0 Regarding relative humidity, all three rooms mostly lie within category II (Table 21). The living room has the least time in category III and the East room has the most among others. All the time in this category is due to humidity levels between 60-70%. In general, humidity levels are too high but is mainly caused by high outdoor levels. Thus, dehumidification during summer is impractical as most of the time doors and windows are open as a natural behavior of occupants for operating their homes.

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Study cases in Crete 6.5.6

EVALUATION OF THERMAL COMFORT IN LSC AND STONE DURING 20.09.2015 – 03.11.2015

Table 22. Amount of time within categories for temperature ranges in LSC and STONE houses (prescriptive model).

Prescriptive model 20.09-03.11 (% of occupied hours) LSC STONE Living room West bedroom East bedroom Living room Bedroom upstairs Guest bedroom Class I 71,2 71,3 64,8 68,6 68,0 72,2 Class II 19,0 11,7 22,5 10,3 8,3 6,2 Class III 8,6 15,2 12,7 14,2 4,0 7,9 Out of range 1,2 1,9 0,0 6,8 19,8 13,6 Table 23. Amount of time within categories for temperature ranges in LSC and STONE houses (adaptive model).

Adaptive model 20.09-03.11 (% of occupied hours) LSC STONE Living room West bedroom East bedroom Living room Bedroom upstairs Guest bedroom Class I 52,5 29,7 43,7 11,5 12,5 13,9 Class II 39,8 27,6 25,2 26,6 26,4 27,1 Class III 7,1 38,2 24,5 35,8 32,2 34,6 Out of range 0,6 4,5 6,6 26,1 28,9 24,4

According to the prescriptive model (Table 22), the LSC house is performing better than the STONE house, where all three rooms have more than 5% of the time out of category III. This is due the cold period below 20 °C. The bedroom upstairs and the West bedroom – the two coolest rooms perform worst. Otherwise, thermal conditions in both houses for most of the time falls into category I. The adaptive model (Table 23) evaluated the LSC house performing better than the STONE house, but the performance for both houses is much lower. The model suggests that it is too cold indoors. Most of the time the thermal comfort conditions in the STONE house falls into category III or even below and should cause very high dissatisfaction by the occupants. In reality, during the warm period the occupants did not have any complaints about too low temperatures indoors and guests visiting the house, who were not living in a stone house, would express their satisfaction regarding the thermal comfort of the building.

After all, both models agree that LSC is performing better.

Table 24. Amount of time within categories for relative humidity ranges in LSC and STONE houses.

Relative humidity 20.09-03.11 (% of occupied hours) LSC STONE Living room West bedroom East bedroom Living room Bedroom upstairs Guest bedroom Class I 0,9 0,1 0,6 0,0 0,0 0,0 Class II 19,2 7,5 10,7 2,0 1,6 2,0 Class III 79,8 88,2 87,0 62,7 80,3 52,3 Out of range 0,1 4,1 1,7 35,4 18,0 45,8

The relative humidity levels for the LSC house almost all the time lie in category III, whereas in the STONE house the levels for a significant amount of time is even below category III (Table 24). The Guest bedroom has relative humidity above 70% for 45,8% of the time, which is a signal of potential mold problems in the room. Very high outdoor humidity levels should be taken into account when interpreting the results. In order to reach more acceptable humidity levels, constant dehumidification should be applied. Anyhow, in practice, it was not observed nowhere in the village.

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Study cases in Crete 6.5.7

DISCUSSION ON ADAPTIVE AND PRESCRIPTIVE THERMAL COMFORT MODELS

The prescriptive and adaptive thermal comfort models gave different results as expected. Both of them have their limitations for the investigated cases. The prescriptive model is not meant to tolerate higher temperatures, which are present during all the summer in Crete in not mechanically cooled buildings. Also, during hot days occupants were very likely to wear down to 0,2 clo, where the model is limited to 0,5 clo. The adaptive model was expected to cope with high temperatures and it did so, but surprisingly resulted in quite low performance during the still warm autumn period suggesting temperatures were too low indoors. Especially for the STONE house, which had lower temperatures.

This is contradicting with the observation of thermal sensation by the occupants and guests visiting both houses. The thermal conditions in the STONE house during the warmer period were preferred to the ones in the LSC. This is the limitation of the adaptive model to these cases as occupants could freely choose to be outdoors if they thought temperatures were too low, which is still a private area belonging to their homes.

To improve the accuracy of predicted thermal comfort for the study cases according to observations would be a modification to the adaptive model – an extension of the lower horizontal indoor temperature threshold to the right side. In other words, merging lower limits of the prescriptive model with higher limits of the adaptive one.

6.6 CONCLUSIONS  

  

69

Indoor temperatures were lower and more stable during the warmer period in the STONE house. The LSC had stable temperatures starting from the cold period.

The thermal comfort in the uninsulated STONE house is unacceptable as soon as outdoor temperatures drop below 20 °C while LSC house performance is still acceptable with even no heating involved.

The evaluation of the thermal comfort and the relative humidity showed that generally LSC is performing better than the STONE house.

The absolute humidity is very stable in the LSC house between different rooms suggesting that the clay plaster is working actively in the regulation process of absolute humidity indoors.

Interior plaster in the LSC house could not stabilize relative humidity levels, as described in literature and were always higher than 50% showing that the clay could not cope with the warm and humid climate.

TECHNICAL UNIVERSITY OF DENMARK

Study cases in Denmark

7 STUDY CASES IN DENMARK The criteria to evaluate the indoor climate were used as described in Section 6.1.1, except for thermal performance. Only the prescriptive model was taken into consideration from DS/EN15251. The graphs describing the whole period of measuremnets can be found in Appendix F.

7.1 OUTDOOR MEASUREMENTS In this part, two straw bale houses were continuously measured by the Hobo data logger during the period from 15.11.2015 to 17.12.2015 The idea is to study how these types of buildings are performing in a cold climate, where people spend around 90% of their time indoors and windows stay closed most of the time; therefore, stable conditions of indoor climate are easily achieved.

The logger was set outside of the Konkyliehuset on a table under a large overhang at the west side wall. The outdoor conditions can be seen in the graph below (Fig. 82).

Figure 82. Outdoor measurements exported by Hobo data logger.

The selected period to be investigated started the 15th of November when the measurements stood steady and finished the 17th of December before the sensors were placed back in the car.

The CO2 sensor was not working since the beginning, therefore, values below -1200, which act as an indication of malfunction, were neglected.

Table 25. Outdoor conditions for the period of 15.11 2015 - 17.12.2015

70

15.11.2015 to 17.12.2015

Temperature, °C

Min Max Average Standard deviation

-4.65 11.44 5.50 2.81

Relative humidity, % 62.54 92.22 84.65 3.25

Dew point

CO2, ppm

Moisture content, g/kg

-6.69 9.52 3.11 2.7

346.88 445.62 377.18 13.50

2.41 7.82 5.09 0.97

TECHNICAL UNIVERSITY OF DENMARK

Study cases in Denmark

30 26 22 18 14 10 6 2 -2 -6 -10

100 90 80 70 60 50 40 30 20 10 0 0

10

20

30

40

50

60

70

80

90

Relative Humidity, %

Temperature, °C

Outdoor measurements 15.11.2015 to 17.12.2015

100

Culmulative frequency, % Temperature

Relative humidity

Figure 83. Outdoor measurements plotted as a function of cumulative frequency for the period of 12.15.2015-12.17.2015

7.2 FRI OG FRO Fri og Fro is an ecovillage that was established in 2004 as a cooperative in Egebjerg region. The cooperative consists of 16 members and 16 detached houses. The goal of the cooperative is to maximize sustainability in terms of usage of resources, hence, the houses are mainly built from recycled materials like wood, straw, clay, sea mussels and very often also reused windows and doors. A willow evaporation plants had also been built, which provide wastewater treatment. In total, 9 out of the 16 houses are straw bale houses. The dominant winds are blowing from the North-West as is for all Denmark. Roskilde Fjord is at a distance of 2.7 km from the village.

Figure 84. Wooden house built from recycled timber and tiles.

Figure 85. Fri og fro village

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Study cases in Denmark

Figure 86. Straw bale house with green roof in Fri og Fro (picture by Author)

Figure 87. House in Fri og Fro built from recycled timber (picture by Author)

Figure 88. Straw bale house. The association's community center. (Picture by Author)

Figure 89. House in Fri og Fro made of recycled wood Figure 90. Straw bale house in Fri of Fro (picture by Author) insulated with paper wool and covered with scrap scaffolding plates. (Picture by Author)

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Study cases in Denmark 7.2.1

KONKYLIEHUSET

Konkyliehuset, is a combination of two words, konkylie that derives from the Greek word (κοχύλι) that means seashell and the Danish word huset that stands for house. The reason for choosing this name is nothing else than it was a seashell that triggered the inspiration of the owner to build alike.

Figure 91. Konlyliehuset (picture accessed by Paula-Line Schmidt in 2015)

The construction started in 2006 and finished in 2011. Paula, the owner, built her house along with friends and members of Fri og Fro. House specifications/characteristics: 

      

Area: the ground floor consists of 75 m2 where two bedrooms, kitchen, toilet, bathroom, living room and storage place can be found. Upstairs the square meters are not defined, however, there are teo bedrooms, storage place and common area.

Load-bearing frame: Logs Straw bales infill: Laid flat, , 50 cm in width Exterior plaster: Lime with pigments Interior plaster: Loam - 3 layers Floor: Beeswax, linoil, loam, seashells for drainage, reused plastic (radon consideration), water hoses Ventilation system: natural (windows-doors) Heating system: bio-oven. An efficient rocket stove taking the surplus heat from the solar collectors and providing floor heating and hot water.

Long-term measurements Two sets of measurement devices were installed. One upstairs in the common area and one in the living room next to the bedroom.

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Study cases in Denmark 7.2.2

SPUNKHUSET

The Spunkhuset has a floor area of 160 m2. There are five bedrooms, a work room, a very large living space with kitchen and a toilet. The owners, Lars and Helle, together with friends finished it in October of 2010.

Figure 92. Spunkhuset (picture by Author)

House specifications/characteristics:       

Load-bearing frame: Timber Straw bales infill: Laid flat, thickness of 45cm Exterior plaster: 3 layers loam covered with water-glass Interior plaster: Loam - 3 layers Floor: loam (15cm), seashells (70cm) for drainage Ventilation system: natural (windows-doors) Heating system: bio-oven. An efficient rocket stove taking the surplus heat from the solar collectors and providing floor heating and hot water.

Long-term measurements Two sets of measurement devices were installed. One in the parents’ bedroom and the other in the living room.

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Study cases in Denmark Table 26. Occupancy schedule

Occupancy Konkyliehuset

1-2 adults 1 kids

Spunkhuset

3 adults 2 kids

Reference house

Occupancy schedule

Ventilation strategy Varied, mainly 2 scenarios.

Not 1. 7-9am leaving the ventilating house the house 19-20pm returning.

2. All day long in the house 

weekdays Morning empty Evening 5 people



Weekends All day 5 people Weekdays 7.30-8am leaving the house 14-17.30 returning Weekends Unoccupied 10-14



3 persons 1 dog



Firing the wood burner 2-3 times per day

Not particular schedule, depending on the sensation to cold

Reference house Although, the reference house was measured during another period, which was between 25.10.2010 to 26.11.2010, the outdoor conditions were similar and, therefore, valid for comparison. It is a 135m2 detached brickwork single family house built in 1964.

30 26 22 18 14 10 6 2 -2 -6 -10

100 80 60 40 20

Relative humidity, %

Temperature,

Outdoor conditions for reference case 25.10.2010 - 26.11.2010

0 0

10

20

30

40

50

60

70

80

90

100

Culmulative frequency, % Temperature

Relative humidity

Figure 93. Outdoor measurements for reference house plotted as a function of cumulative frequency for the period of 25.10.2010 - 26.11.2010

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Study cases in Denmark

7.3 MEASUREMENTS AND COMPARISON TO THE REFERENCE HOUSE. In appendix F can be found wide graphs of the whole measurement period. For a better understanding it is suggested to have the graphs open while reading the following cumulative frequency graphs.

Temperature, °C

Temperature

Temperatures

29 27 25 23 21 19 17 15 13 11 9 7 5 3 1 -1 -3 -5 0

10

20

30

40

50

60

70

80

90

100

Cumulative frequency, % Outdoor Konkyliehuset Upstairs Spunk Huset Bedroom Refference bedroom

Konkyliehuset Living room Reference Livingroom Spunk Huset Livingroom

Figure 94. Temperatures comparison plotted as a function of cumulative frequency for the period of 15.11.2015 – 17.12.2015

In the Spunkhuset, between the living room and the bedroom it was recorded a difference of temperature of 2 °C . Whereas, in the Konkyliehuset, ground floor and first floor seemed to perform in the same way. Regarding the reference house, in the living a temperature above 26°C for 43% of the time has been registered. Unstable temperatures between the two rooms of the reference house can be observed. Overall, the reference house, seems not to adjust to high temperatures as efficiently as the straw bale houses. This could be a result of numerous factors such as the construction itself, ventilation strategy, heating set points, but also the occupants’ behavior. (Fig. 94)

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Study cases in Denmark

Relative humidity

Relative humidity

90 85 80

Relative humidity , %

75 70 65 60 55 50 45 40 35 30 25 0

10

20

30

40

50

60

70

80

90

100

Culmulative frequency, % Outdoor Konkyliehuset Upstairs Spunk Huset Bedroom Refference bedroom

Konkyliehuset Living room Reference Livingroom Spunk Huset Livingroom

Figure 95. Relative humidity comparison plotted as a function of cumulative frequency for the period of 15.11.2015 â&#x20AC;&#x201C; 17.12.2015

Fig. 95 indicates that the relative humidity is quite stable, 13% fluctuations (min-max), and values were within the acceptable range in both houses of interest, i.e. 50% of the time having less than 50% of relative humidity in all the cases. RH is very stable between the houses but also between the rooms of the same houses (it can also be seen for the whole measurement period in appendix F) within the ranges of 40-55% all the time. Regarding the reference house, in the bedroom, 20% of the time the relative humidity was above 60%. In the reference living room, however, the relative humidity seems to be unstable. Unstable RH between the two rooms of the reference house can be observed.

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Mixing ratio, g/kg

Study cases in Denmark

Moisture content g/kg

11 10.5 10 9.5 9 8.5 8 7.5 7 6.5 6 5.5 5 4.5 4 3.5 3 0

10

20

30

40

50

60

70

80

90

100

Culmulative frequency, % Outdoor Spunk Huset Livingroom Konkyliehuset Upstairs Konkyliehuset Living room

Spunk Huset Bedroom Refference bedroom Reference Livingroom

Figure 96. Moisture content comparison plotted as a function of cumulative frequency for the period of 15.11.2015 â&#x20AC;&#x201C; 17.12.2015

From the Figure 96 it is observed that, the two straw bale houses are performing in a very similar way with stable curves for all the time period. The moisture content is higher than outdoor and that is explained due to the indoor temperature being much higher that the outdoor. The reference house has a higher of 2g/kg compared to the straw bale houses during all the time of recording. However, according to the Danish standards (DS/EN15251), the moisture content should be below the level of 12g/kg. Therefore,all investigated houses are within this level.

LIVING ROOM

UPSTAIRS

KONKYLIEHUSET

1887.28 988.63

117.02

1373.51 206.62

289.10 507.10 381.23

703.00 213.12

1.44

127.37

10.81

1173.94

1330.81

(DEDUCTED BACKGROUND)

136.34

4000.00 3500.00 3000.00 2500.00 2000.00 1500.00 1000.00 500.00 0.00

12.38

CO2 CONCENTRATION, PPM

CO 2 CONCENTRATION

3465.49

CO2 concentration

min max

average

BEDROOM

LIVING ROOM

SPUNK HUSET

BEDROOM

LIVING ROOM

REFERENCE HOUSE

Figure 97. CO2 concentration comparison plotted as a function of cumulative frequency for the period of 15.11.2015 17.12.2015

Even though in the two straw bale houses the owners prefer not to ventilate adequately, the CO2 concentration seems to be much higher in the reference house. The average CO2 levels for the straw bale houses are below category I criteria, with an exemption in the living room of Spunkhuset that is just above this level.

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Study cases in Denmark Daily Fluctuations

Temperature, C

Another way for comparing the houses is through the analysis of fluctuations occurring during each day. Fluctuations or not-stable temperatures can cause local discomfort and often lead to complaints from the occupants. The method used in this investigation consisted in calculating the minimum, the maximum and the difference between them of every 24 hours for the whole measurement period.

The difference between max and min was indicating the daily fluctuations. This has been done for all three parameters: temperature, relative humidity and moisture content as it can be seen in the cumulative graphs below (Fig.98,99,100).

Daily fluctuations Temperatures

10 9 8 7 6 5 4 3 2 1 0 0

10

20

30

40

50

60

70

80

90

100

Culmulative frequency, % Outdoor Konkyliehuset upstairs Spunk Huset livingroom Reference LivingRoom

Konkyliehuset livingroom Spunk Huset bedroom Reference Bedroom

Figure 98. Temperature daily fluctuations plotted as a function of cumulative frequency for the period of 15.11.2015 17.12.2015

The bedroom of the Spunkhuset presented the highest range, according to Fig. 98, of temperature fluctuations - 30% of the time higher than 3 degrees in daily temperature differences. However, that is a tolerable fluctuation, likely to occur in a bedroom. The most stable in terms of temperature fluctuations is the reference bedroom - 70% of the time less than 1 degree in daily difference.

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Relative humidity, %

Study cases in Denmark

Daily fluctuations Relative humidity

20 18 16 14 12 10 8 6 4 2 0 0

10

20

30

40

50

60

70

80

90

100

Culmulative frequency, % Outdoor Konkyliehuset upstairs Spunk Huset livingroom Reference LivingRoom

Konkyliehuset livingroom Spunk Huset bedroom Reference Bedroom

Figure 99. Relative humidity daily fluctuations plotted as a function of cumulative frequency for the period of 15.11.201517.12.2015

The higher relative humidity fluctuations were registered in the reference living room, being 30% of the time more than 10% in daily difference. Konkyliehuset performs the most stable by having 70% of the time less than 5% of relative humidity daily differences in both spaces.(Fig. 99)

Mixing ratio, g/kg

Moisture Content Daily fluctuation 5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 0

10

20

30

40

50

60

70

80

90

100

Culmulative frequency, % Outdoor Konkyliehuset upstairs Spunk Huset livingroom Reference LivingRoom

Konkyliehuset livingroom Spunk Huset bedroom Reference Bedroom

Figure 100 Moisture content daily fluctuation plotted as a function of cumulative frequency for the period of 15.11.201517.12.2015

For both straw bale houses, moisture content was stable, and below the outdoor level for most of the time. The average moisture content for the bedroom of Spunkhuset (which had the highest values besides the referent case) was 1.25 g/kg, relatively a very small value. The reference living room has as an average fluctuation of 1.90 g/kg.(Fig. 100) 80

TECHNICAL UNIVERSITY OF DENMARK

Study cases in Denmark

7.4 AIR CHANGE RATE The Spunkhuset will be used in order to quantify the potential air leakages. From the Hobo logger that was installed in the bedroom, the amount of air that was coming in the structure but also the amount flowing out can be estimated. During the night, when the occupants are sleeping, CO2 is generated whereas in daytime, when occupants are not in the house, the CO2 is returning to normal levels. This process of CO2 decay takes time and by the needed time it can be estimated how fast the old air is changed by fresh air that comes in and get mixed with the CO2.

The air change rate (n) was calculated according to the equation below. Firstly, by taking three graphs of CO2 concentration for 3 different days starting at 7.00am one can find the CO2 decay curve of each day. Later, after the calculations of each air change rates was done, the average was found.

C(t) = Co * e-nΔt

(4)

Where C(t) - concentration of CO2 at the start of test [ppm]; C0 - concentration of CO2 at the end of the test, [ppm]; n - air change rate, [h-1] and Δt - time interval between the measurements.

CO2 Decay 03.12.15 07:08-15:08

y = 669.81e-0.015x

250

y = 733.1e-0.017x

CO2 Decay 04.12.15 07:08- 16:08 CO2 concentration, ppm

CO2 concentration , ppm

CO2 concentration ,ppm

CO2 Decay 17.11.15 8:58-14:28

250

250

Time (mins)

Time (mins)

Time (mins)

Spunk Huset Bedroom

Spunk Huset Bedroom

Spunk Huset Bedroom

y = 570.86e-0.022x

Figure 101. CO2 decay curve for 3 days Table 27 Calculated Air changes per hour

Time and date of measurement

Air changes per hour (h-1)

17.11.15 8.58-14.28

0.9

03.12.15 07:08-15:08

1.02

04.12.15 07:08-16.08

1.32

Average

1.08

The Figure 101 showcases the decay curve of CO2 concentration in the bedroom. From the equation above, the average air change was calculated to be 1.08 h-1. However, it has to be noted that the actual infiltration might be lower since the occupants were leaving the bedroom’s door open after leaving the room.

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Study cases in Denmark

7.5 EVALUATION OF INDOOR CLIMATE The ranges that are suggested by the DS/EN15251 are given in the section 6.1.1.

Only prescriptive model will evaluete the indoor climate. The adaptive model will not be used since it does not comply with climates below +10°C. Defining the occupancy was the difficult part here. The Konkylienhuset did not have a systematic occupancy schedule; hence, defining the occupancy through the CO2 was not possible. Moreover, in the reference house, the CO2 fairly drops in levels where one could define the occupancy. Through interviewing both straw house owners, it was found out that the closest-to-reality way to define the occupancy is via the indoor temperature. As both said, when the temperature drops below approx.

20-19.5°C then the occupants are feeding the fire. Therefore, taking into account the living room’s temperature drop below 19.5°C during daytime it was defined as “no occupancy”. Regarding the reference house’s occupancy, the schedule that was given by the occupants was followed in the calculations below.

Table 28 Thermal comfort classification according to DS/EN15251

Perscriptive thermal comfort model (occupied hours) Temperature Konkyliehuset Spunk Huset Reference house Category range, C Living room, % Upstairs, % Living room, % Bedroom, % Living room, % Bedroom, % Class I 21-25 34.6 30.5 31.0 96.6 56.4 67.6 Class II 20-25 44.2 45.5 47.8 3.3 0.0 32.5 Class III 18-25 21.2 24.0 21.3 0.0 0.0 0.0 Out of range

0.0 100.0

0.0 100.0

0.0 100.0

0.1 100.0

43.6 100.0

0.0 100.0

According to the thermal comfort model, the Konklyliehuset lies within the category II for most of the occupied time. The Spunkhuset lies between categories I and II with a clear superiority in the bedroom where 96.6% of the occupied hours it lies in category I. The reference house lies in category I most of the time while the temperatures in the living room are exceeding 25°C for about 43.6% of the time.

This are clearly overheating problems occurring in the reference bedroom. (Table 14) Table 29 Relative humidity classification according to DS/EN15251 Relative humidity (occupied hours) Konkyliehuset Spunk Huset Reference house Category RH range, % Living room, % Upstairs, % Living room, % Bedroom, % Living room, % Bedroom, % Class I 30-50 55.1 82.0 56.6 84.3 50.1 0.9 Class II 25-60 45.0 18.1 43.4 15.7 46.1 78.5 Class III 20-70 0.0 0.0 0.0 0.0 3.8 20.6 Out of range 0.0 0.0 0.0 0.0 0.0 0.0 100.0 100.0 100.0 100.0 100.0 100.0

Regarding relative humidity (Table 29), both straw bale houses are performing mostly within the category I with the living rooms – including the reference living room – being sharing an almost equal share in category II. The reference bedroom lies most of the time in category II but also 20% in category I.

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Study cases in Denmark Table 30 CO2 concentration classification according to DS/EN15251 Konkyliehuset Category Class I Class II Class III Class IV

CO2 concentration Spunk Huset

Reference house

CO2 range Living room, % Upstairs, % Living room, % Bedroom, % Living room, % Bedroom, % Below 350ppm 97.6 97.2 84.7 21.1 0.9 3.7 350 - 500ppm 1.3 1.7 13.9 46.6 1.2 4.8 500 - 800ppm 0.7 0.7 1.4 0.1 9.1 15.5 >800ppm 0.3 0.4 0.0 0.0 88.8 76.1

In table 30, the CO2 levels are indicating Konkyliehuset within category I with an outstanding 97.2%.

Spunkhuset lies within category I and II while the reference house lies mainly in “category IV”. It is worth mentioning that the sensor in the bedroom of the reference house was 40% of the time not logging CO2 concentration.

7.6 DISCUSSION Both straw bale houses performed within the standards of the perscriprive model of DS/EN 15251 with very few exception of being out of the range. All the graphs showed very stable values without any abnormal curves. The comparison to the reference house did show a clear superiority concerning the indoor climate. The CO2 concentration levels, for the straw bale houses, were most of the time within class I and II (below 500ppm). By interviewing the house owners, it was reported that both houses were usually not ventilated. This leaves space for the only possible interpretation that the infiltration rates must be quite high. In the reference house, however, which is known to be very airtight, the CO2 concentration levels were kept at very high levels, being most of the time above the recommended value of 800ppm and reaching the maximum of 3465.5ppm. Perhaps the energy consumption in the two straw bale houses would be increased due to the suspected infiltration rate, nevertheless, the occupants seem to enjoy this compensation.

7.7 CONCLUSIONS 

 

83

The similarities in the straw houses between them and also between the rooms within the same houses, but also the significant differences in comparison to the reference house, support the hypothesis that clay plaster is affecting the indoor moisture levels.

Straw as insulation and the great amount of clay as thermal mass, are stabilizing the indoor temperatures for the two study cases.

The possible high infiltration rate favors the CO2 levels for both straw bale houses that were within class I and II for most of the time.

TECHNICAL UNIVERSITY OF DENMARK

Energy simulations for study case in Crete

8 ENERGY SIMULATIONS FOR STUDY CASE IN CRETE The measurements of the two study cases in Crete were carried for a few months during a warm period when heating was not used. In order to see differences in energy consumption, simulations using IDA ICE software were made. In order to achieve the most comparable conditions, the same occupancy schedules, ventilation strategies and temperature set-points were used. Differences in orientation, shadows cast by neighboring objects, the geometry of the houses, and the area of the windows were kept as original. Later on, LSC house was simulated with some optimization solutions to achieve better thermal comfort and energy consumption.

8.1 EXPERIMENT ON THERMAL CONDUCTIVITY OF INFILL OF LSC WALLS As no thermal conductivity tests for the specific technique of making straw and clay infill in the LSC house were found through literature research, it was decided to make an independent experiment to have a more realistic value for the simulations. Few additional methods of making the mixture were added to investigate if it could result in a lower thermal conductivity.

8.1.1

METHODOLOGY

The experiment was carried out using a guarded hot plate stationary device at DTU. The apparatus is built as stated in requirements of EN 12664 and is used to measure thermal conductivity according to the same standard. It was used as described in the manual (Peuhkuri, 2013).

Figure 102. Construction of the guarded hot plate apparatus.

To insulate samples a rigid 26x26x5 cm frame from 2 cm thick extruded polystyrene was constructed with an additional layer of 5 cm thick soft mineral wool from the sides. A 30x30 cm cooling plate was matching the polysterene frame. Sensors on the cooling (A) and heating (B) sides in the measurement area of 16x16 cm (center) were attached to 1 mm thick polyester foam mats (influence of the mats is assumed to be negligible as they were in between the sensors and the heating/cooling plates).

Samples were measured until temperature difference between A and B was constant. For most of the specimens, it took around two days.

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Energy simulations for study case in Crete Temperature difference between A and B sensors was measured and thermal conductivity could be found based on Fourierâ&#x20AC;&#x2122;s law: đ?&#x153;&#x2020; (5) đ?&#x2018;&#x17E; = â&#x2C6;&#x2122; (đ?&#x2018;&#x2021;đ?&#x2018;§ â&#x2C6;&#x2019; đ?&#x2018;&#x2021;đ?&#x2018;Ś ) đ?&#x2018;&#x2018; đ?&#x153;&#x2020;=

đ?&#x2018;&#x192;â&#x2C6;&#x2122;đ?&#x2018;&#x2018; đ??´ â&#x2C6;&#x2122; â&#x2C6;&#x2020;đ?&#x2018;&#x2021;

(6)

Where đ?&#x2018;&#x17E; â&#x20AC;&#x201C; heat flux, [W/m2] đ?&#x153;&#x2020; â&#x20AC;&#x201C; thermal conductivity [W/mK] đ?&#x2018;&#x192; â&#x20AC;&#x201C; deposed power of the heating plate, [W] đ?&#x2018;&#x2018; â&#x20AC;&#x201C; thickness of the sample, [m] đ??´ â&#x20AC;&#x201C; measured area of 16x16cm, [m2] â&#x2C6;&#x2020;đ?&#x2018;&#x2021; â&#x20AC;&#x201C; temperature difference across the sample, [°C] đ?&#x2018;&#x192;=

đ?&#x2018;&#x2C6;2 24,8

(7)

Where đ?&#x2018;&#x2C6; - voltage measured through the heating plate, [V] (24,8 is the resistance in the heating plate)

8.2 SPECIMENS Nine specimens were measured during the experiment. Seven of them were made of loose straw rinsed with either clayey water or just water. One specimen was only from straw and one was a mineral wool sample.

All the samples had the dimensions of 26x26x5 cm to fit the frame in the apparatus. Loose straw was rinsed with water or clayey water (liquid substance, where clay deposits on the bottom of a bucket, regardless of stirring) and put in a square box to form the desired shape (Fig. 103). The mixture was compressed by hand. Afterwards, specimens were dried in an industrial oven at 50 °C until the mass was constant. Additional weights on the top were used during the drying period until the experiment to keep the desired thickness.

Figure 103. Left â&#x20AC;&#x201C; specimens in a box before drying. Right â&#x20AC;&#x201C; specimen ready for the experiment.

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Energy simulations for study case in Crete The first sample was a mineral wool with known đ?&#x153;&#x2020;-value (0,041 W/mK) to verify if the apparatus was correctly calibrated. Next three samples named â&#x20AC;&#x153;clay-waterâ&#x20AC;? were made using the original technique from the LSC house. Straw was rinsed with the clayey water, initially compressed by hand and no additional weights during drying were used for two lighter specimens. The heavier sample included additional clay from the bottom of the bucket in the mixture. Also a 60 kg mass for initial compression and constant 20 kg weight during drying was used in order to reach higher density. Four specimens named â&#x20AC;&#x153;waterâ&#x20AC;? were rinsed with only pure water and initial compression was done by hands. Different weights (6-20 kg) during the process were used, which resulted in different densities. The last sample was made from a loose straw bale (not completely loose straw â&#x20AC;&#x201C; some of the original compression was left).

8.2.1

RESULTS

Loose strawbale - 41,0 kg/m3

0.044

Water - 38,6 kg/m3

0.044

Specimen (density)

Water - 56,2 kg/m3

0.044

Water - 53,8 kg/m3

0.044

Water - 45,6 kg/m3

0.048

Clay-water - 45,9 kg/m3

0.053

Clay-water - 45,9 kg/m3

0.055

Mineral wool - 72,0 kg/m3

0.041

0.040

0.042

0.044

0.046

0.048

0.050

0.052

0.054

0.056

Thermal conductivity, W/mK Figure 104. Thermal conductivity measurements.

Results (Fig. 104) showed unexpectedly low thermal conductivities for both techniques â&#x20AC;&#x201C; straw mixture with clayey water and only with water as standardized value for straw bales is 0,052 W/mK (Austrian Standard). Mixtures with only water had lower thermal conductivity values than the group of mixtures with clayey water. Even the very small amount of clay added in the mixture have increased the values. The noticeable remark is that difference in densities of mixes with water did not have a tangible effect on the results â&#x20AC;&#x201C; all the samples had almost the same thermal conductivity. The loose straw bale sample had the same results as well, suggesting that compression at least in this range of densities is not a significant factor for the results. The more conservative đ?&#x153;&#x2020;-value of 0,055 W/mK were later used in simulations.

8.2.2

DISCUSSION

During measurements periodic apparatus malfunctions of not know cause were observed. It might have distorted results of a few specimens. However, the influence observed was small and results were not disregarded. More detailed information is presented in Appendix D. 86

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Energy simulations for study case in Crete

8.3 INPUTS FOR SIMULATIONS 8.3.1

CLIMATE DATA

A IWEC2 format weather file for the city of Heraklion (altitude 39m) was used in simulations. Average weather parameters are showed in Table 31. Even though both study cases are situated 15km from Heraklion, the higher elevation and mountainous terrain makes the local climate different. Differences between measurements and simulations are expected.

Table 31. Average monthly climate data for Heraklion.

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Temp, °C

12,2

11,3

13,1

15,8

18,9

23,4

26,2

25,8

23,6

20,2

16,3

14,0

RH, %

70,4

67,0

67,1

63,7

66,5

56,9

56,7

62,6

63,0

65,6

69,3

66,1

Radiation, 151,2 186,1 207,6 252,5 292,6 322,4 324,2 300,4 269,2 218,4 166,3 142,9 W/m2

8.3.2

GEOMETRY AND STRUCTURAL DETAILS

Figure 105. Left –3D model of the LSC house. Right – 3D model of the STONE house.

Floor plans for the STONE and LSC houses are given in Section 6.3 (Figure 61, Figure 64, Figure 65).

The two houses have very similar floor area and envelope area per volume (Table 32). The biggest difference is windows’ area. LSC has 12,54 m2 south facing windows compared to the 5,02 m2 of the total area of windows in the STONE house. U-values of the envelopes are significantly different with a clear superiority of the LSC. While LSC is considered as a well-insulated building, the STONE house is very poorly insulated. Exact U-values and composition of walls can be found in Tables 33-34.

Table 32. Geometry and structural details of STONE and LSC houses.

STONE

LSC

Model floor area

81,3 m2

78,1 m2

Model volume Model ground area Model envelope area Window/Envelope

227,7 m3

264,5 m3

47,4 m2

69,9 m2

236,9 m2

288,9 m2

2,1 %

6,3 %

Average U-value Envelope area per Volume

2,096 W/(K·m2)

0,7854 W/(K·m2)

1,04 m2/m3

1,093 m2/m3

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Energy simulations for study case in Crete Area, m2

U, W/m2K

Area, m2

U, W/m2K

Walls above ground

128,60

2,251

126,65

0,282

Roof

48,31

0,58

71,77

0,43

Floor towards ground

47,39

1,03

69,88

0,61

Windows

ESE 1,03 WNW 3,99

5,42

NNE 2,52 ESE 1,71 SSW 12,54 WNW 1,35

2,81

Doors

5,16

1,90

2,52

1,90

Total

236,88

2,10

288,94

0,79

1

– all external walls are from limestone, except 16.86 m2 of unheated extension concrete walls 2 – all external walls are from straw-clay (LSC), except 9 m2 of southern wall of the living room from adobe bricks LSC house Table 33.External and internal walls construction definitions of LSC house.

External LSC wall Inside

Thickness, m 0,05

λ, W/mK 0,91

Clay plaster Straw-clay 0,35 0,067 infill Clay plaster 0,05 0,91 Outside 0,45 U-value=0,18 W/m2K

External adobe bricks wall

Internal LSC wall

Clay plaster

Thickness, m 0,05

λ, W/mK 0,91

Adobe bricks

0,35

Clay plaster

0,05 0,45 U-value=1,5 W/m2K

Floor

Clay plaster

Thickness, m 0,05

λ, W/mK 0,91

0,75

Straw-clay infill

0,1

0,067

0,91

Clay plaster

0,05 0,91 0,2 U-value=0,48 W/m2K

Roof

Laminate Mud A3 stone Pumice Gravel

0,01 0,13 0,02 1,1 0,15 2 0,05 0,25 0,15 2 0,38 U-value=1,53 W/m2K

Wooden boards Mineral wool Air gap OSB Ceramic roof tiles

0,01 0,05 0,2 0,022 0,01 0,29 U-value=0,43 W/m2K

0,13 0,036 0,39 0,13 1,2

STONE house Table 34.External and internal walls construction definitions of STONE house.

External stone wall Thickness, Inside m Lime render 0,01 Limestone 0,58 Lime render 0,01 Outside 0,6

λ, W/mK 0,87 2,2 0,87

U-value=2,19 W/m2K

Floor Thickness, λ, m W/mK Floor tiles 0,01 1,6 Limestone 0,1 2,2 Gravel 0,1 2 0,21 U-value=3,73 W/m2K

88

External concrete wall Lime render Concrete Lime render

Thickness, m 0,01 0,25 0,01 0,27

Internal wall

λ, W/mK 0,87 1,7 0,87

U-value=2,94 W/m2K

Gypsum board Air gap Gypsum board

Thickness, m 0,013 0,1 0,013 0,125

λ, W/mK 0,22 0,39 0,22

U-value=2,21 W/m2K

Roof Thickness, m Wooden boards 0,025 Mineral wool 0,05 Asphalt paper 0,005 Ceramic roof tiles 0,01 0,29 U-value=0,43 W/m2K

λ, W/mK 0,14 0,036 0,17 1,2

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Energy simulations for study case in Crete 8.3.3

OCCUPANCY SCHEDULES AND OPERATION STRATEGIES

Occupancy schedule and principle ventilation strategy of the STONE house was applied for the LSC house as well. Heating setpoints of 20 째C were used for both houses.

Table 35. Occupancy, occupancy schedules, ventilation strategies of LSC and STONE houses for simulations.

Occupancy schedule

Occupancy

2 adults +1 adult on Sundays

Mon-Fri 16:0009:00 Sat 16:00-10:00 Sun 18:00-10:00

STONE

LSC

10.06 to 25.09 doors are open when occupants are at home

10.06 to 25.09 doors are open when occupants are at home

25.05 to 05.06 windows are open when occupants are not at home 06.06 to 01.10 when occupants are at home Rest of the time (cold) - 10 min cross ventilation every day at 18:00 and 22:50

25.05 to 05.06 and 02.10 to 30.10 windows are open when occupants are not at home 06.06 to 01.10 when occupants are at home Rest of the time (cold) - 10 min cross ventilation every day at 18:00 and 22:50

No shading devices were used for the STONE house, as solar gains are already very low throughout the year. In the LSC house, where solar gains are very high - external shutters are drawn for all southern windows except in the dining room (broken in reality) when occupants are not at home from 25.05 to 20.10.

Natural ventilation strategies were optimized for each room according to their individual conditions.

For example, in the living rooms during cold season cross ventilation is applied only at 18:00 when CO2 levels due to two hour presence of occupants becomes around 1200 ppm. Bedrooms are cross ventilated just before the occupants are using the room at night, ensuring the lowest possible CO2 levels. In spring and autumn time, opening of windows and doors is adjusted for each room depending on the thermal conditions indoors to prevent heating and ventilation at the same time.

8.4 RESULTS 8.4.1

COMPARISON OF ENERGY CONSUMPTION BETWEEN STONE AND LSC HOUSES

The STONE house had much higher energy consumption (Table 36) because of its poor thermal insulation. According to the adaptive thermal comfort model, the uninsulated house performed significantly worse as well. However, temperatures above 27 째C were occurring more rarely. This corresponds well to the actual measurements in both houses according to indoor temperature.

Table 36. Energy consumption and adaptive thermal comfort results of STONE and LSC.

Time in category, % Yearly energy consumption for heating, kWh/m2

Time when T>27째C in the worst zone, %

Time when T>27째C in average zone, %

Time with thermal dissatisfaction of occupants, %

I

II

III

Out of range

LSC

11

15

6

9

76,4

19,6

3,1

0,9

STONE

87

15

8

12

36,8

13,7

42,1

7,3

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Energy simulations for study case in Crete 8.4.2

OPTIMIZATION OF LSC HOUSE

Optimization on site In order to improve thermal comfort in theLSC house, few optimization actions were done during the authors stay in Crete. During a big storm prior to the measurements, external shutters of the dining room were damaged, hence, the room could not be shaded effectively anymore. As the big windowdoor is facing south, high solar gains were increasing the already high indoor temperature. To prevent this, a pergola was constructed. Freshly cut bamboos were used for the covering, imitating vegetative design - during warm months the plants of the pergola grow leaves and drop the shade, whilst in colder months the leaves are gone and most of the light can pass through and enter the building.

Unfortunately the pergola was finished right at the time, when outdoor temperatures dropped down and influence of the pergola could not be clearly seen in the measurements. Another modification to enhance cross ventilation was done by taking out a small fixed window facing east, high above the kitchen accessed from the lower flat roof. However, it was also finished during the temperature drop and the result could not be justified.

Figure 106. Left â&#x20AC;&#x201C; pergola in construction. Right â&#x20AC;&#x201C; opening of a taken out window.

Theoretical optimization Both modifications together with other improvements were tested in whole year simulations in IDA ICE. Each modification was tested separately to see the individual impact on the results.

No adobe brick wall South overhang +1 m Small window open Roof insulation +15 cm Internal wall plaster +10 cm External wall plaster +5 cm Combined

90

9 m2 south facing adobe brick wall (originally designed for storing thermal mass) in the living room was replaced by LSC wall as the rest of the external walls.

Overhang on the south side of the roof was increased by 1 m.

The fixed window was fully open from 25-05 till 01-10 insulation was added to have U-value of the roof lower than the one of the walls 5 cm of clay plaster was added on each side of the internal walls 5 cm of clay plaster was added on the internal side of the external walls All the beneficial improvements were simulated together (No adobe brick, south overhang +1 m, small window open, roof insulation +15 cm, internal wall plaster +10 cm)

TECHNICAL UNIVERSITY OF DENMARK

Energy simulations for study case in Crete Table 37. Energy consumption and adaptive thermal comfort results of optimization of the LSC house.

Time in category, % (1)

Reference No adobe brick wall South overhang +1m Small window open Roof insulation +15cm Internal wall plaster +10cm External wall plaster +5cm Combined 1

Yearly energy consumption for heating, kWh/m2 11

Time when T>27째C in the worst zone, % 15

Time when T>27째C in average zone, % 6

10

15

14,4

Time with thermal dissatisfaction of occupants, %

I

II

III

Out of range

9

76,4

19,6

3,1

0,9

6

9

77,4

18,4

3,2

1,1

13

6

9

71,9

23,2

4,2

0,7

11

15

6

9

76,3

19,6

3,2

0,9

7,1

13

5

9

78,0

17,9

3,1

1,0

10,2

14

6

9

76,1

20,1

3,1

0,8

15,9

13

6

10

42,0

52,7

4,5

0,7

5,8

12

5

9

78,8

16,8

3,3

1,1

0.5h-1

Infiltration is as suggested from IDA ICE. The values are comparable since the increased infiltration would affect all the cases. However, the consumption would be slightly increased.

8.5 DISCUSSION - CONCLUSION Outcomes of the optimization in Table 37 show, that the replacement of the adobe wall by well insulated LSC type wall resulted in a lower energy consumption and a small improvement in thermal comfort. A small reduction of temperatures by thermal mass in summer are overwhelmed by cause big losses of heat during cold moths.

The increase of the south overhang gave a negative effect on energy and overall thermal performance, as solar gains during cold months were lowered. However, it reduced the time of occupied hours with temperatures above 27 째C in the worst zone by 2 %, which in this case was the dining room having no external shutters. Anyhow, the overhang in the simulation was fixed throughout the year and does not include the dynamically changing solar permeability of a vegetative pergola.

Opening the small window did not have any beneficial on the evaluated parameters. The size of the opening is too small to have an influential effect on ventilation. Despite that, it helped to lower CO2 concentration in the house, therefore, the modification was included in the combined case.

The addition of 15 cm of insulation to the roof gave U-value of 0,15 W/m2K compared to the previous 0,43 W/m2K. This lowered annual energy consumption by 3,9 kWh/m2. The initial higher U-value of the roof compared to the external walls was a poor design. The modification also reduced a number of hours with temperatures above 27 째C, as during summer indoor space is heated by conduction through the roof.

The addition of 10 cm of clay onto the internal walls slightly improved all the results, while the case with the addition of 5 cm of the plaster to the internal side of the exterior walls gave a much worse 91

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Energy simulations for study case in Crete performance in all the compared criteria. The higher thermal mass inside was accumulating heat in both cases, but when the plaster was on the external walls, the stored heat was more easily transferred to the outside. The heat stored in the internal walls could only release heat into the ambient air and not directly to the outside.

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Straw as a solution in low-cost Renovations

9 STRAW AS A SOLUTION IN LOW-COST RENOVATIONS The need for renovating existing conventional buildings is crucial for many countries around the world especially in developing countries and in countries where the financial crisis is not leaving space for development. Generally, the building sector is a main contributor to global GHG emissions, accounting for 1/3 of total GHG emissions and 40% total energy consumption (UNEP, 2009).

Moreover, in these cases, people are using any kind of heating, having a great impact on the environment. For example, during the latest financial crisis in southern Europe and due to the higher taxation in fuels - the heating oil cost up to 40% more than before (Reuters, 2011)- people started using wood burners. Since wood also adds costs, they ended up burning furniture and salvaging wood (Paphitis N., 2013). It should be noted that furniture is not pure wood but consists of toxic glues, plastic covers, noxious varnishes and other synthetic matter. This brought clouds of thick smoke consisting of heavy metals over the big city centers. (Reuters, 2011) The authorities warned of multiple and severe health risks and inhabitants of Athens and Thessaloniki reported that they were confined in their own houses for weeks because of their fear to breathe the polluted air surrounding the cities (BBC News, 2013). People with breathing problems got literally trapped indoors.

According to Eberle et al, (2012), the European Union contributed 70% of the total cost in order to refurbish energy-wise the main households - “Energy Efficiency of Household Buildings” Programme.

This regards insulation of the external walls and roofs, changes in fenestration elements (use of lowenergy elements), and changes in solar collectors and boilers. However, this program took place during the financial crisis and most of the households could not afford their economical contribution (30%). According to a report conducted by the Ecologic Institute in Berlin (Eberle et al, 2012), Greece emitted 115.0 Mt CO2eq in 2011. This report reveals a 10% increase compared to the 1990’s.

As it is summarized in the chapters above, straw is a material that has three great advantages: 1. Great thermal properties, 2. Is a significant cheap solution, 3. Acts as a sink of greenhouse gasses.

A façade made entirely from renewable sources combines low budget effective solutions and, at the same time, it can ensure insulation properties of a passive house standard without any particular professional skill. Hence, it would be a very good solution for both the inhabitants, the owner, and eventually the global climate.

Although insulating new and existing buildings located in capital centerssolely with straw bale techniques seems unrealistic, it would reduce CO2 emissions from the building sector by about 26%.

(Wihan J., 2007) Moreover,a façade made of straw, after its life span it will biodegrade without leaving any ecological footprint behind. Therefore, being a sustainable measure also in terms of waste material.

A potential obstacle might be the local regulations as it is for the case of Greece where it is stated that for building a thermal façade of more than 6cm in thickness , a building license is required. Taking

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Straw as a solution in low-cost Renovations into account that by building license it means that the costs for the study, the signatures, the supervision, bureaucratic costs, etc. the final structureâ&#x20AC;&#x2122;s costs and needed time, will increase significantly.

9.1 IMPLEMENTATION As an example, the study case of the stone house in Archanes will be used. Here, only the walls will be improved. Although, the roof, where most of the heat losses occur, is not going to be improved. It is possible to insulate also the roof in straw, however, a lot of detailing need to be taken into consideration.

9.1.1

THE STONE HOUSES

Stone houses were and still are popular in warm climates since they provide a stable temperature through the summer.

The stone houses are houses that depend solely on the high thermal mass of the stone that surrounds them. Stone is a material with large heat storage capacity with small variations depending on the type of stone.

Most of the stone houses, if not all, are not insulated at all. People tend to believe that stone is providing thermal properties but this is not completely correct. Thermal mass adds very few thermal insulation properties. The inhabitants of a stone house are heating their house in the day time and expect it to provide heat during the night time without any further heat input. This should be the case, however, it needs a lot of time in order to feel the effect of it.

There are two temperature sources in the case of an external wall acting simultaneously, the outdoor temperature and the indoor one. Both are taking over the heat storage capacity. The outdoor temperature, which is colder, is moving towards the inside and ends up being stored in the stone.

Simultaneously, the indoor heat is acting in the same but opposite way.

It is obvious that the needed heat, in order to overcome the cold side has to be abundant and intensive. As people living in stone houses in north Greece are reporting, they start heating their houses in September in order to have them warm in November.

Moreover, those structures are having condensation problems. As the inhabitants genuinely report, the walls during the winter are â&#x20AC;&#x153;cryingâ&#x20AC;?. In the following figures the performance of common limestone wall is noted (Fig. 107-111).

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Straw as a solution in low-cost Renovations

Figure 107. U-value and temperature profile calculated by U-wert. Material properties changed by the author in accordance to (Eppelbaum, L. 2014)

As can be seen from the Figure 107, a typical limestone wall of 50cm thickness with lime render is having a high U-value of 2.48 W/m2K far from the passive house standard.

Additionally, condensation is very likely to occur. Finally, the protection against heat (during cooling season) adds a great advantage to the structure.

Figure 108. Humidity profile of Limestone wall calculated by U-wert. Material properties changed by the author in accordance to (Eppelbaum, L. 2014)

Figure 109. Temperature profile of Limestone wall calculated by U-wert. Material properties changed by the author in accordance to (Eppelbaum, L. 2014)

The Figures 108 &109 showcase the temperature profile during the daytime. This is the case of the cooling season where heat has to be kept out of the house. It is evident that even in an outdoor temperature drift of 14°C the indoor temperature will stay stable, with very small fluctuations.

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Straw as a solution in low-cost Renovations Energy consumption There is need to note that the inputs and considerations regarding the simulations are explained in the previous chapter.

This chapter demostates the annual energy savings in fuel consumption. Lighting, domestic hot water, and other energy consuming sources will not take part here since there will not be affected by the implementation of the new thermal façade. In the end of this chapter, the comparison to the costs of building the façade is shown. kWh 2000 1800 1600 1400 1200 1000 800 600 400 200 0 1

2

3

4

5

6

7

8

9

10

11

12 Month

Figure 110. Monthly delivered energy for the actual house - simulated in IDAICE software Table 38. Annual delivered energy for the actual house - simulated in IDAICE software

Delivered energy kWh kWh/m2 Lighting, facility

391

4.8

Fuel heating

7076

87.0

Grand total

7467

91.9

W Year: 2015

1500

1000

500

0

-500

-1000

Jan 0

Feb 1000

Walls Roof Floor

Mar 2000

Apr

May 3000

Jun 4000

Jul 5000

Aug

Sep 6000

Oct 7000

Nov

Dec 8000

Windows Doors Thermal bridges

Figure 111. Envelope transmittion for the actual house - simulated in IDAICE software.

As can be seen in Figure 111 the envelope’s transmittion is mainly through the walls and floor.

Therefore, as first priority is to examine whether by renovating only the walls would have a difference that compensates to the expenses. Later on, the roof will be examined as well.

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Straw as a solution in low-cost Renovations 9.1.1

THERMAL FAร ADE (WRAPPING)

By implementing a straw faรงade of 18cm,the render can have many variations. Lime covered wood wool (Heraklith), will be used for the example (Fig. 112). Regarding the energy simulations, the inputs were the same for both cases; hence, factors such as infiltration rates, which would be improved after the renovation, were not changed due to lack of valid assumptions.

Figure 112. U-value and temperature profile for a new wall element with straw insulation of 18cm calculated by U-wert

Figure 113. Humidity profile for new wall element with straw insulation of 18cm calculated by U-wert

The humidity profile (Fig. 113) of the thermal faรงade is not indicating condensation problems.

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Straw as a solution in low-cost Renovations

Figure 114. Temperature profile for new wall element with straw insulation of 18cm calculated by U-wert

The temperature is stabel before it reaches the stone part of the wall and the small fluctuation that were observed before the implementation, tend not to occur in this case. (Fig. 114) Energy consumption kWh 900 800 700 600 500 400 300 200 100 0 1

2

3

4

5

6

7

8

9

10

11

12 Month

Figure 115. Renovated stone house (wall) - Monthly delivered energy simulated in IDAICE software Table 39. Renovated stone house (wall) – Annual delivered energy simulated in IDAICE software

Delivered energy kWh kWh/m2 391

4.8

Fuel heating

3092

38.0

Grand total

3483

42.8

Lighting, facility

Table 40. Renovation Costs for Thermal façade (based on local prices, January 2016)

Costs for Thermal façade (wrapping) Material Quantity 3 Straw, m 23.15 2 Heraclith 0.35mm, m 128.60(1) Lime (1cm thick), m3 1.29 Timber (20x2x100cm), m 144.00(2) Screws, brackets, chicken net, etc.

4€ per m of timber 3 Gravel for drainage, m 0.33(3) Scaffolding rental, €/day 3 (4) Wages, pers.

3 Total 1 Area

Cost, € 18.18€*23.15m3= 420.87€ 7.5€*128.6m2= 964.50€ 80€*2.29m3= 102.88€ 2.3€*144m=336.00€ 4€*144m= 590.4€ 20€*0.33m3= 6.54€ 3€*10d= 30€ 50€*3pers.*10d= 1500.00€ 3936.79€ 30.61€/m2

to be covered in new thermal facade. at every meter.

2 Studs

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Straw as a solution in low-cost Renovations 3

Height*width*length = 0.2m*0.05m*32.7m. are indicative and assumed based on current financial situation in the market. For skilled workers, it might increase.

10 days are assumed to be needed for the completion of the thermal façade.

4 Wages

9.1.2

RENOVATED ROOF

20cm thich layer of straw was implemented to the roof. Two roof types are present in the current house (Fig. 117 & 118). Since the village is a prototype and itâ&#x20AC;&#x2122;s esthetic should not be disturbed, the tiles on the multi-pitched roof will cover the wood wool (Heraklith), as before. The tiles and the pine rafters are assumed to be reused from the old roof. Regarding the energy simulations, the inputs were the same for both cases; hence factors such as infiltration rates, which would be improved after the renovation, were not changed due to lack of valid assumptions. The flat roof in Fig. 117 is going to have an inclination of 3%.

Figure 116. U-value and temperature profile for a new flat roof element with straw insulation of 20cm calculated by U-wert

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Straw as a solution in low-cost Renovations

Figure 117. U-value and temperature profile for new multi-pitched roof element with straw insulation of 20cm calculated by U-wert

Condensation is not likely to occur in this design. Humidity and temperature profiles more analytical can be found in Appendix D. kWh 800 700 600 500 400 300 200 100 0 1

2

3

4

5

6

7

8

9

10

11

12 Month

Figure 118. Renovated STONE house (wall & roof) - Monthly delivered energy simulated in IDAICE software Table 41. Renovated STONE house (wall & roof) â&#x20AC;&#x201C; Annual delivered energy simulated in IDAICE software

Delivered energy kWh kWh/m2 391

4.8

Fuel heating

2715

33.4

Grand total

3106

38.2

Lighting, facility

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Straw as a solution in low-cost Renovations

Table 42. Renovation Costs for Thermal façade & Roof (based on local prices, January 2016)

Costs for flat roof Quantity Price Cost, € 18.18 2.77 m3 50.32 €/m3

Material Straw (20cm) Heraklith 0.35mm Asphaltpaper Timber (22x2cm) Screws, brackets, chicken net, etc.

Scaffolding rental, day Wages(3)

Costs for multi-pitched roof Quantity Price Cost, € 18.18 7 m3 127.62 €/m3

Total Cost, € 177.95 367.05

13.84m2 (1)

7.5€/m2

103.8

35.10 m2 (1)

7.5€/m2

263.25

13.84 m3

3.6€/m

49.82

35.1 m3

3.6€/m

126.36

176.18

14.2 m (2)

9€/m

127.8

35.9 m (2)

9€/m

323.1

450.9

7 € per m of timber

99.4

7 € per m of timber

251.3

350.7

3 days

3€/day

9

7 days

3€/day

21

30

3pers*3days

50€/day

450 890.14

3pers*7days

50€/day

1500

1050

2162.63

3052.78

61.61€/ m2

62.38€/ m2

Total

64.32€/ m2

1 Area

need to be renovated. at every meter.

3 Wages are indicative and assumed based on current financial situation in the market. For skilled workers, it might increase.

10 days are assumed to be needed for the completion of the thermal façade.

Note: For simplicity reasons the discount rates to calculate the net present value for future prices are not taken into account.

2 Studs

9.1.3

OVERALL

Table 43. Thermal comfort for actual and renovated stone house. Renovated compared to the actual house.

Time in category, %

Adaptive thermal comfort model

STONE actual STONE renovated roof only STONE renovated walls only STONE renovated wall & roof

101

Yearly energy consumption for heating, kWh/m2

Time when T>27°C in the worst zone, %

Time when T>27°C in average zone, %

Time with thermal dissatisfaction of occupants, %

87

15

8

12

73.7

14

8

37.4

7

33.4

6

II

III

Out of rang e

36.8

13.7

42.1

7.3

11

36.2

13.8

42.7

7.4

4

10

34.7

28.1

35.4

1.8

3

10

33.3

29.1

35.4

2.2

I

TECHNICAL UNIVERSITY OF DENMARK

Straw as a solution in low-cost Renovations

Table 44. Annual savings from heating after renovating

Actual Stone house

Euros per kWh (Greece) (Energypress, 2015) 0.208

Thermal façade

0.208

3092

643.14

675.29

Thermal façade & roof

0.208

2715

564.72

592.95

(1)A

Total kWh

Annual costs, â&#x201A;Ź

7076

1471.80

If Ρ=0.95(1), â&#x201A;Ź 1545.40

Savings, â&#x201A;Ź

870.11 952.44

heating source with efficiency of 95%.

Payback period (years) =

Initial investment cost Annual operating savings

(8)

Financies, â&#x201A;Ź

Cash flow (10 years) 8000.00 6500.00 5000.00 3500.00 2000.00 500.00 -1000.00 -2500.00 -4000.00 -5500.00 -7000.00 0

1

2

3

4

5

6

7

8

9

10

11

Time period (t)(years) Net savings-Thermal facade (incl. labor)

Net savings-Thermal facade(excl. labor)

Net savings-Thermal façade&Roof(inc.labor) Figure 119. Net savings (t) = cost (t) - savings (t) Note: renovation takes place in t=1 10

đ??śđ?&#x2018;&#x17D;đ?&#x2018; â&#x201E;&#x17D; đ?&#x2018;&#x201C;đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;¤ = â&#x2C6;&#x2018;(Net savings(t)) đ?&#x2018;Ą=0

(9)

The Cash Flow graph shows the interaction of costs and savings over time. Looking at the curve one can observe that, following the investment initially made for the renovation of only the wall, the owner accumulates up to 8701.06 â&#x201A;Ź in savings over a period of 10 years. From the curve one can also see that the payback period is about 4.52 years.

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TECHNICAL UNIVERSITY OF DENMARK

Straw as a solution in low-cost Renovations Moreover, by summing up the savings of 10 year period and dividing that with the investment costs (savings/investment ratio), one can conclude that for every euro spent on renovation, the owner (investor) saves 2.21€.

By considering a self-made renovation (i.e. by taking off the cost of labor), the picture looks even more favorable. The payback period of the thermal façade goes down to 2.8 years while the savings/investment ratio increases to 3.5.

For renovating the wall but also the roof, one can see that the payback period comes in 7.33 years and the ratio savings/investment decreases down to 1.36.

9.1.4

DISCUSSION

Although, most of the heat losses occur through the roof, the roof of the study case had initially a basic insulation, whereas the walls were totally uninsulated. As expected, the roof did not improve much the energy consumption neither the indoor thermal comfort. Hence, the walls had a larger impact on heat losses. For this study case, the expenses compared to the savings did not convince for renovating the roof. Insulating stone houses require a dynamic occupant behavior for the summer time. Stone houses are used in warm climates since it has the ability, due to the high conductivity that stone possesses, to cool down during the night. When insulating it, the occupant has to block the outdoor heat during the day time (Toutdoors>Tindoors) by the use of windows and shutters, and ventilate during the night time.

9.1.5

CONCLUSIONS

Considering the fact that the floor was not renovated and also that for the simulations the thermal bridges were not improved, from the results it can be concluded that:    

103

By renovating only the wall, the overall annual fuel consumption was reduced by 37%, saving annually the amount of 870.11 €.

With only a 4 month heavily heated period the renovation will pay back in 4.52 years.

The straw insulation is keeping the cold out of the thermal mass, and therefore, internal heat will actively take part in the thermal mass.

For the particular case, the roof (plus wall) renovation had a lower impact increasing the paying back period in 7.33 yeas adding only 82.33€ on the total annual savings.

TECHNICAL UNIVERSITY OF DENMARK

Straw as a solution in low-cost Renovations

9.2 EXISTING EXAMPLE The picture below depicts a three family-house, which was originally built in the ‘60s in Germany. It consists of two floors, basement and attic and has an area of 310m2. It was renovated in 2013 by the architect and owner Jörn Schöbel. The attic has been entirely dismantled and rebuilt increasing the height of the ceiling to 3.2m. The existing exterior walls were insulated with 40cm of straw bales and plastered with 3 layers of clay and a final layer of lime. Textiles (coffee bags) were used between layers.

A new straw bale wall was built in front of the ex-balconies. Complying with the local architecture, wood covers the plaster (rain screens) both in south and east, due to the small overhang but also because of the dominant winds.

The wall’s U-value from 1.04 W/m2K was optimized into 0.12 W/m2K with the thermal facade addendum.

The renovated new thermal façade (wrapping), covers 193m2 of the whole façade whilst the new straw bale wall consists of 62m2. Hulled wheat whole straw bales were used.

Jörn Schöbe used the whole straw bales (not flakes) laid flat, with the fibers parallel to the heat flow and perpendicular to the ground. The reason, as he explained, was that in this configuration, it leaves less space for compression and therefore with conic wood spacers in every two rows of straw bales he achieved the maximum compression. The conic wooden spacers were hammered in after the straw bales reached the top and screwed with stainless screws.

This technique ensures a good stability and compression for the new thermal facade. (Fig. 119)

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Figure 120. Wall assembly. Conic wooden spacers at every 2 straw bale rows, enhancing compression and stability

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Straw as a solution in low-cost Renovations

Figure 121. A 3 family house renovated with straw in Emmering, Germany, 2007 (before renovation) (accessed by Jรถrn Schรถbe)

Figure 122. A 3 family house renovated with straw in Emmering, Germany, 2016 (after renovation) (picture by Author)

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Straw as a solution in low-cost Renovations

Figure 124. Roof and window detail (accessed Figure 123. Section A-A (accessed by Jörg Schöbel, 1.1.1016)

by Jörg Schöbel, 1.1.1016)

The section plan A-A depicts part of the new straw bale wall on the right and left side while the left upper part of the wall consist of the renovated thermal façade.

Table 45. Costs for renovating Jörg Schöbel house in straw.

Costs Renovated thermal façade (Wrapping) approx 158 € / m² Plaster (incl textiles, screws etc) € 74 / m² New straw bale wall (both sides) (incl. plaster and approx € 251 / m² paint)

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Conclusions

10 CONCLUSIONS Measurements were taken and analysed to investigate straw/clay houses regarding their performance in different climates. The first set of study cases took place in the warm and humid climate of Crete (Greece) while the second in the temperate and humid climate of Denmark. Both were compared to local conventional/traditional buildings. IDA ICE yearly simulation continued the assessment that the time-limited measurements were not able to. PAQ of clay plaster and thermal conductivity experiments of the LCS technique were conducted as part of the investigation.

A questionnaire gathering 67 straw/clay replies from three different continents gave a large amount of data and confirmation to the literature.The questionnaire confirmed the literature in many fields.

Mainly the questionnaire responses underlined the factors to be avoided when building a straw/clay house e.g. small overhang problem, the use of linoil on the external finishing, etc. Most of the owners were self-builders, hence, by having experience with their house were able to offer a great deal of information. Although, 57% of the participants reported from minor to large problems indicating that non-professionals self-builders might not completely coprehent building physics. From the followed study cases, it seems that they have a spherical understanding in building sustainable dwellings with satisfactory indoor climate and energy consumption.

The small-scaled PAQ experiment on clay plaster and painted gypsum board finishes compared with and without exposure to tobacco smoke (THS) were assessed. In regards to PAQ acceptability, odor intensity, and irritation no statistically significant differences between the materials were found.

Though, the case exposed to tobacco smoke showed that panellists could not identify the origin of the odor, which was not the case for the painted gypsum sample. Clay plaster seemed to neutralize the tobacco odor.

The active role of clay plaster was observed from measurements of the study cases; both in Crete and in Denmark. For two study cases in the cold and humid climate, the levels of relative humidity were stable and within the range of 40-55%. A study case in Crete showed that the moisture content was almost identical in all the rooms of the LSC house. However, relative humidity for the most of the time was in the range of 60-75%, meaning that even the high moisture capacity of clay plaster could not cope with the warm and humid climate.

Both study cases in Denmark confirmed that the internal thermal mass of clay plaster and earthen floor stabilizes the indoor temperature during the heating season. Simulations in IDA ICE showed that the most beneficial strategy of using thermal mass of clay plaster is to prevent direct connection to the external envelope. Heat accumulated in the plaster on the external walls is â&#x20AC;&#x153;lostâ&#x20AC;? to the outside much faster, than if it is kept without a direct contact with the external envelope.

The study cases in Denmark showed that straw as insulation and clay having the role of thermal mass improves and stabilizes the indoor climate. Moreover, the two straw bale houses performed successfully within the Danish national standards in regards to indoor climate, while the compared reference house was often out of the ranges. The very low CO2 concentrations in the straw bale houses (below 500ppm) while no ventilation took place, suggested that the infiltration rates were quite high.

Furthermore, the very high CO2 concentrations that were registered in the Danish reference house (most of the time above the recommended values), suggest a very air tight building. Questions are

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Conclusions open regarding the benefits of air tightness. Perhaps the better indoor climate compensates a higher energy consumption.

The LSC house proved to perform satisfactorily throughout the whole measurement period, including the hot summer days with outdoor temperature above 30°C and the cold period below 20°C (without heating). A secondary finding was the inaccuracy of the adaptive thermal comfort model (DS/EN 15251) used for the evaluation. In order to obtain realistic results, an individual adaptive model for the location correcting lower temperature limits should be made.

Energy simulations in IDA ICE started with an experiment to determine the thermal conductivity of the straw and clay mixtures used for infill in the LSC house. As the density for the specific technique in Crete was found to be lower (40-50 kg/m3) than the one described in the literature (400-1200kg/m3) classifying the LCS, further researched was conducted. This unique building technique was named Light Straw Clay (LCS). The λ-value which was found in the experiments to be 0.054 W/mK is very close to the one for straw bales (0,052 W/mK) with the twice lower density for the LSC. This technique saves a significant amount of straw and requires less manpower. Nonetheless, further tests (e.g. fire safety) have to be done in the future.

The yearly IDA ICE simulation of the LSC house resulted in a very low energy consumption of 11 kWh/m2, which fully complies with the requirements of a passive house. Additional improvements lowered the consumption down to 5.8 kWh/m2. Smart design utilizing high solar gains had a big impact on this. Simulations also showed that the house is performing very well throughout the whole year.

The yearly simulation for the Stone house revealed very high energy consumption of 87 kWh/m2 and poor thermal performance as well, mostly because of the too low indoor temperatures. This was also observed from the measurements when outdoor temperatures dropped below 20 °C. The finding suggests that even in the warm climates poorly insulated stone buildings are, perhaps, in need of renovation Renovation techniques involving straw as the key insulation material is feasible to be used for conventional residential households. The study case of the stone house in Crete showed that an investment in a straw thermal façade can pay back the total amount in 4.5 years with only a 4 month heavily heated period (as it is in Crete). Furthermore, it showed that during the winter, straw insulation is keeping the cold out of the thermal mass, and therefore, internal heat will actively take part in the thermal mass. Hence, keeping the house warm without heating for a longer period. In this study case, the fuel consumption was diminished by 37%. Flat but also pitched roof can as well be renovated in straw. Nevertheless, insulating stone houses require a dynamic occupant behavior for the summer time. Stone houses are popular in warm climates since it has the ability, due to the high conductivity that stone possesses, to cool down during the night. When insulating it, the occupant has to block the outdoor heat during the day time (Toutdoors>Tindoors) by the use of windows and shutters, and ventilate during the night time.

All in all, many points described in the literature were confirmed by the study cases and the global questionnaire. Measurements and simulations showed a satisfactory performance of straw bale and LSC houses - both in a warm and humid climate of Crete as well as in a cold and humid climate of Denmark.

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References

11 REFERENCES Bryman, 2008. A. Bryman, Social Research Methods, Oxford university press Carter, 2012. John Carter, “Nebraska’s Straw Bale Church” Cop21, 2015. Conference of the Parties, twenty-first session, ADOPTION OF THE PARIS AGREEMENT, Paris, 30 November to 11 December 2015 Darling et al. 2012. Erin K., Clement J. Cros, Pawel Wargocki, Jakub Kolarik, Glenn C. Morrison, and Richard L. Corsi. 2012. “Impacts of a Clay Plaster on Indoor Air Quality Assessed Using Chemical and Sensory Measurements.” Building and Environment 57. Elsevier Ltd: 370–76. doi:10.1016/j.buildenv.2012.06.004.

Donovan et al, 2009. D. Donovan, S. Khan, B. Donovan, Pakistan Straw Bale and Appropriate Building (PAKSBAB), www.paksbab.org, Earthquake Engineering Reasearch Institute (EERI), University of Nevada, Reno DS/EN 15251. 2007-06-22, Danish standards, “Indoor environment input parameters for design and assessment of energy performance of building addressing indoor air quality , thermal environment, lighting and acoustics”.

Eberle et al, 2012. Andrew Eberle, Lena Donat, Eike Karola Velten, Georgios Maroulis, Ecologic Institute -eclareon, Assessment of climate change policies in the context of the European Semester Eppelbaum, L. 2014. Eppelbaum, L, Applied Geothermics, Thermal Properties of Rocks and Density of Fluids, Springer-Verlag Berlin Heidelberg Faine et al, 2000. Michael Faine and Dr. John Zhang “Pilot Study: Two Storey Load Bearing Straw Bale Wall”, University of Western Sydney Australia Gonzales, 2013. Gonzales Alejandro D. Energy and carbon embodied in straw and clay wall blocks produced locally in the Andean Patagonia, 2013 Goodhew et al. 2010. Steve Godhew, Jim Carfrae and Pieter De Wilde, Briefing: Challenges related to straw bale construction Jones B., 2001. Barbara Jones B., Amazon nails, Todmorden, UK, Information guide to straw bale building Kalogiannaki, 2015. Kalogiannaki Evangelia. MSc Architecture: Advanced Energy and Environmental Studies, Center of Alternative Technology, Wales, "Earth and Straw Constructions in Crete, Future potentials."

MacMath, R. 2000. Richard MacMath, CARBON DIOXIDE INTENSITY RATIOS: A Method of Evaluating the Upstream Global Warming Impact of Long-Life Building Materials, 2000,[Internet] Available from: http://www.cmpbs.org/sites/default/files/t1.2-ad4.5-up_gbl_wrm.pdf, Accessed 1.28.2016.

Mar, 1998. Avid Mar, FULL SCALE STRAW BALE VAULT TEST, structural Engineers, Berkeley California Matt et al. 2011. Georg E, Penelope J E Quintana, Hugo Destaillats, Lara A Gundel, Mohamad Sleiman, Brett C Singer, Peyton Jacob,. “Thirdhand Tobacco Smoke: Emerging Evidence and Arguments 109

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References for a Multidisciplinary Research Agenda.” Environmental Health Perspectives 119 (9).

[National Institute of Environmental Health Sciences, Brogan & Partners]: 1218–26.

Munch & Møller, 2004. Jørgen Munch-Andersen, Birte Møller Andersen, Halmhuse, Udformning og materialeegenskaber, By og Byg Resultater 033 Myhrman & MacDonald, 1997. Matts Myhrman and S. O. MacDonald Build it with Bales A Step-byStep Guide to Straw-Bale Construction Møller, 2001. Birte Møller Andersen, DELTA Dansk Elektronik Lys & Akustik, Måling af Iuftlydisolation for lerpudsede halmvægge i eiendom beliggende Obispo SL. 2000. San Luis Obispo , Architectural Engineering department of California Polytechnic state university, Straw Bale shear Wall Lateral Load Test Power, 2008. Anne Power, “Does Demolition or Refurbishment of Old and Inefficient Homes Help to Increase Our Environmental, Social and Economic Viability?” Foresight Sustainable Energy Management and the Built Environment Project 36 (12): 4487–4501. doi:10.1016/j.enpol.2008.09.022.

Ramírez et al. 2014. Noelia, Mustafa Z. Özel, Alastair C. Lewis, Rosa M. Marcé, Francesc Borrull, and Jacqueline F. Hamilton. “Exposure to Nitrosamines in Thirdhand Tobacco Smoke Increases Cancer Risk in Non-Smokers.” Environment International 71. Elsevier Ltd: 139–47. doi:10.1016/j.envint.2014.06.012.

Rockström et al. 2009. Rockström, Johan, W. Steffen, Kevin Noone, Åsa Persson, F. Chapin, Eric Lambin, Timothy Lenton, et al. 2009. “Planetary Boundaries: Exploring the Safe Operating Space for Humanity.” Institute for Sustainable Solutions Publications and Presentations, January. http://pdxscholar.library.pdx.edu/iss_pub/64.

San, 2007. San Rafael, ASTM E 119-05a, Fire Tests of Building Construction and Materials, 2-HR Fire resistance test of non-loadbearing straw bale wall Steen, 1994. Steen, Athena; Bill; Brainbridge, David; Eisenberg, David: The Straw Bale House, Chelsea Green Publishing, Vermont/Totnes Singer et al. 2003. Brett C., Alfred T. Hodgson, and William W Nazaroff. 2003. “Gas-Phase Organics in Environmental Tobacco Smoke: 2. Exposure-Relevant Emission Factors and Indirect Exposures from Habitual Smoking.” Atmospheric Environment 37 (39-40): 5551–61. doi:10.1016/j.atmosenv.2003.07.015.

Theis, 2003. Bob Theis, Ecological Building Network (EBNet), “Straw bale fire safety” Vaisala, 2014.

Vaisala Product offering.

[Online] Available at: http://www.vaisala.com/en/products/carbondioxide/Pages/GM20.aspx [Accessed 22.11.2015].BBC News, Mark Lowen BBC, Katerini, and northern Greece. 2016. “Crisis-Hit Greeks Chop up Forests to Stay Warm.”

Accessed January 20. http://www.bbc.com/news/world-europe-21202432.

Wihan, J. 2007. “Humidity in Straw Bale Walls and Its Effect on the Decomposition of Straw.” MSc. University of East London School … 44 (0): 271.

Williams et al. 2013. R. Williams, N. Poole, T. Fraser, D. Grant, N. Hanson, J. Orson, P. Rolston, J. Sim Foundation for Arable research, “Review of the role and practices of stubble burning in New Zealand, including alternative options and possible improvements”, Report No. R13/86 Environment Canterbury Woolson, R. F. 2008. Wilcoxon Signed‐Rank Test. Wiley Encyclopedia of Clinical Trials.

Books Minke, 2000. Gernot Minke; “Earth Construction Handbook, the Building Material Earth in Modern Architecture”, WIT Press Southapton , Boston

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References Minke and Mahlke, 2005. Gernot Minke and Friedemann Mahlke; “Building with Straw, design and technology of a sustainable architecture”. Basel, Berlin, Boston: Birkhäuser Publishers for Architecture King, 2006. Bruce King, “Design of Straw Bale Buildings, The State of the Art”, Green Building Press Wanerk C., 2003. Catherine Wanerk, Utah, “The New Straw bale Home”, Gibbs Smith, Layton.

Siegel S., 1956. Siegel Sidney, “Nonparametric Statistics for the Behavioral Sciences”. New York: McGraw-Hill.

Web links Ammons, 2013. Pat Ammons. “Huntsville’s Burritt Mansion, City’s Oldest Museum, Turns 75.” AL.com.

November 13. Accessed 10.12.2015 http://www.al.com/entertainment/index.ssf/2013/11/huntsvilles_burritt_mansion_si.html.

BBC News, 2013. Mark Lowen BBC, Katerini, and northern Greece. “Crisis-Hit Greeks Chop up Forests to Stay Warm.” Accessed 20.1.2016 http://www.bbc.com/news/world-europe-21202432.

Energypress, 2015. “Electricity Cost Rise in Greece among EU’s Highest in 2014 - ENERGYPRESS.” Accessed 2.2.2016 http://energypress.eu/electricity-cost-rise-in-greece-among-eus-highestin-2014/.

EU, 2011. “Energy markets in the European Union in 2011” Luxembourg: Publications Office of the European Union, 2012.

Accessed 2.11.2016 http://ec.europa.eu/energy/sites/ener/files/documents/20121217_energy_market_2011_lr _en.pdf FAOSTAT, 2013. Agri-environmental indicators database, Food and Agriculture Organization of the United Nations, 2013, http://faostat3.fao.org/home/index.html[ Accessed 10.12.2015 HOBO, 2016. HOBO U12 Temperature/Relative Humidity/Light/External Data Logger.” 2016. Accessed 14.2.2016. http://www.onsetcomp.com/products/data-loggers/u12-012 KENAK, 2010. http://portal.tee.gr/portal/page/portal/tptee/totee/FEK%20407-B-2010%20%20KENAK.pdf Εφημερις της Κυβερνησεως της Ελληνικης Δημοκρατιας τευχος δευτερο. Αρ. Φυλλου 407 Lifelong Learning Programme, 2016. “Straw Leonardo Project | Straw Bale Technique: WRAPPING.” Accessed 3.2.2016. http://www.strawleonardo.eu/best-practice/straw-bale-techniquegalleries-wrapping/.

MNBB, 2012. Mother Nature's Backyard - A Water-wise Garden: Getting to Know Your Garden’s Soil: Simple Soil Tests, http://mother-natures-backyard.blogspot.dk/2012/10/getting-to-knowyour-gardens-soil.html accessed 23.12.2015 Paphtis N., 2013. “In Crisis, Greeks Turn to Wood-Burning – and Choke, By Nicholas Paphitis | Kathimerini.”

Accessed 20.1.2016 http://www.ekathimerini.com/147932/article/ekathimerini/community/in-crisis-greeksturn-to-wood-burning--and-choke Reuters, 2011. “Wood-Burning Stoves All the Rage in Austerity Greece.” Reuters, November.2011, accessed 18.1.2016 Scharmer, 2015. Dirk Scharmer, http://www.strawbalehouse.de/technical-principles.html accessed in 5.1.2016 TLSJ, 2015. The Last Straw Journal, http://thelaststraw.org/ Accessed 21.10.2015 U-Value.net | Current Construction Component. 2016. Accessed 12.2.2016 https://www.u-wert.net

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References UNEP,

2009. Buildings and climate change. UNEP SBCI. Accessed 11.2.2016 http://www.unep.org/sbci/pdfs/SBCI-BCCSummary.pdf Youtube, 2015. Heidi Snel, ecofilm, https://www.youtube.com/watch?v=CoEYHkBT03w, “Größtes Strohballen-Gebäude in Deutschland: "Norddeutsches Zentrum für nachhaltiges Bauen" accessed 3.1.2016 Yr.no. Institutt, 2015. NRK og Meteorologisk. 2015. “Weather Statistics for Archanes.” Yr.no. Accessed 13.10.2015. http://www.yr.no/place/Greece/Crete/Archanes

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Appendix A. Internet survey around the globe

APPENDIX A. INTERNET SURVEY AROUND THE GLOBE Internet survey around the globe Depending the orientation the participants could specify the windowsâ&#x20AC;&#x2122; size, wind chimney was an extra option. Note that for regions in the South hemisphere, like Australia & New Zealand, the window size will differ from those from the North hemisphere.

East/West windows size 79% 80% 60% 40%

57% 43% 35% 29%

43% 35% 29% 29% 21%

53% 29% 29% 10%

20%

0%

14% 0%0%0%0%

0%0%0%0%0% Wind chimney

0% Small windows

North Europe

Medium windows

Big windows

No windows

Central Europe

South Europe

Australia & New Zealand

USA

Figure 125. East/West windows size

North windows size 100% 80% 60% 40% 20% 0%

86% 86% 66% 65% 14%

Small windows

North Europe

86%

29% 14% 14% 12% 0% Medium windows

Central Europe

14% 3%0% 0%

24% 14% 0%0%0%

0%0%0%0%0%

Big windows

No windows

Wind chimney

South Europe

Australia & New Zealand

USA

Figure 126. North window size

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Appendix A. Internet survey around the globe

South windows size 88% 86%

100% 80% 60%

3%6%0%

43% 29% 14% 6%

34%

29%

40% 20%

71%

66%

0%

14%

12% 14% 0% 0% 0%

0%0%0%0%0%

No windows

Wind chimney

0% Small windows

North Europe

Medium windows

Big windows

Central Europe

South Europe

Australia & New Zealand

USA

Figure 127. South window size

Shadings type 100% 80% 60% 40% 20% 0%

86%86% 66%71%

57%57% 43%

43%43%

14% 0%

3% 0%

28%24%

Shutters

North Europe

29% 14%

Curtains

Central Europe

14%

10% 0% Pergola

South Europe

The overhang is enough

Australia & New Zealand

USA

Figure 128. Shading type

Shadings' orientation 80%

71% 69% 57% 43%

60% 40% 20%

14%

43% 29% 14% 3%6%

35%

29% 14% 7% 0%

57% 41% 24% 29% 14%

57% 29% 29% 7%6%

0% South North Europe

North Central Europe

East South Europe

West

Everywhere

Australia & New Zealand

USA

Figure 129. Shadings' orientation

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Appendix B. PAQ Experiment.

APPENDIX B. PAQ EXPERIMENT.

Figure 130. Questionnaire of PAQ experiment

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Appendix B. PAQ Experiment.

Figure 131. Answers of PAQ questionnaire sorted by paramteres and exposure to smoke (1) or any (0) pallotants.

Figure 132. Raw data of PAQ questionnaire.

RAW DATA OF THE EXPERIMENT Sub. No. Chamber Gender Smoker Acceptability scale Odour intensityIrritation Dust 1 1 1 1 0,2 0 0,2 1 2 1 1 0 0,2 0,4 1 3 1 1 0 0 0,2 1 4 1 1 0,3 0,2 0 2 1 1 0 -0,7 0,6 0,1 2 2 1 0 0,8 0 0,1 2 3 1 0 -1 0,8 0 2 4 1 0 0,8 0,2 0 3 1 1 1 -0,8 1 0,9 3 2 1 1 -0,7 0,8 1 3 3 1 1 -1 0,8 0,8 3 4 1 1 0,2 0,2 0 4 1 1 0 -0,9 0,8 0,6 4 2 1 0 -0,7 0,8 0,8 4 3 1 0 0,3 0,8 0,3 4 4 1 0 0,7 0,2 0,2 5 1 1 0 -1 0,8 0,2 5 2 1 0 -0,2 0,2 0 5 3 1 0 -0,8 0,6 0,4 5 4 1 0 -0,6 0,4 0,4 6 1 1 0 -0,7 0,8 0,7 6 2 1 0 0,8 0,1 0,1 6 3 1 0 -0,3 0,5 0,3 6 4 1 0 0,3 0,3 0,2

116

Odour origin Organic Plastic Tobacco Paint 2 3 3 3 4 5 2 4

1 5 5 2

1 2 2 2 2

4 3 3 3

2

1 5 5

5 5 4 5 4 4 5

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Appendix B. PAQ Experiment.

Figure 133. Raw data of PAQ questionnaire.

RAW DATA OF THE EXPERIMENT Sub. No. Chamber Gender Smoker Acceptability scale Odour intensityIrritation Dust 7 1 1 0 -0,6 0,8 0,6 7 2 1 0 0,8 0,2 0,1 7 3 1 0 -0,2 0,6 0,4 7 4 1 0 0,7 0,2 0,1 8 1 1 0 -0,7 0,6 0,6 8 2 1 0 0 0,4 0,2 8 3 1 0 -0,3 0,8 0,4 8 4 1 0 0,8 0,2 0 9 1 1 0 0,9 0,1 0,1 9 2 1 0 0,9 0,3 0,1 9 3 1 0 0,1 0,5 0,5 9 4 1 0 0,6 0,3 0,3 10 1 1 1 -0,4 0,4 0,2 10 2 1 1 0,9 0 0 10 3 1 1 -0,8 0,6 0 10 4 1 1 -0,4 0,4 0,2 11 1 1 1 0,7 0,2 0 11 2 1 1 1 0 0 11 3 1 1 -0,2 0,6 0,3 11 4 1 1 0,9 0,2 0,1 12 1 0 0 -0,7 0,5 0,1 12 2 0 0 0,9 0,1 0 12 3 0 0 -1 1 0 12 4 0 0 0,1 0,2 0 13 1 0 0 -0,1 0,6 0 13 2 0 0 0,1 0,2 0 13 3 0 0 -0,1 0,4 0,2 13 4 0 0 0 0,6 0,4 14 1 1 1 -0,6 0,7 0,3 14 2 1 1 0,3 0,1 0,3 14 3 1 1 -0,3 0,3 0,3 14 4 1 1 0,2 0,3 0,4 15 1 1 0 0,2 0,5 0,1 15 2 1 0 0,3 0,4 0,1 15 3 1 0 -1 0,8 0,6 15 4 1 0 0,2 0,4 0,1 16 1 0 1 -0,7 0,8 0,8 16 2 0 1 0,1 0,2 0,4 16 3 0 1 -0,3 0,6 0,4 16 4 0 1 0,8 0,2 0 17 1 1 0 -0,6 0,7 0,4 17 2 1 0 0,9 0 0 17 3 1 0 -0,9 0,8 0,8 17 4 1 0 0,4 0,5 0,2 18 1 1 0 -0,7 0,7 0,1 18 2 1 0 0,4 0,1 0,1 18 3 1 0 -0,3 0,5 0,1 18 4 1 0 -0,5 0,5 0,1 19 1 1 0 -0,6 0,6 0,2 19 2 1 0 0,3 0,1 0,1 19 3 1 0 -0,8 0,5 0,3 19 4 1 0 0,5 0,3 0 20 1 1 0 -0,8 0,9 0,7 20 2 1 0 0,2 0,5 0,2 20 3 1 0 -0,8 0,9 0,5 20 4 1 0 -0,4 0,7 0,9

117

Odour origin Organic Plastic Tobacco Paint 4 1 1 1 5 1 4 3 3 1 1 2 1 4 2 2 3 5 5 3

4 2 2 5 3 2

2

5 3 5 4 5 5 2

2

3 4 2 1

1 3 1 2

3 1 5 2

4 2 5 2

3 4 3

3

1 4 2 5

3 3 2

3 4 4

5 5 5 4

4 4 4

2 3 4

4 3 5 4

TECHNICAL UNIVERSITY OF DENMARK

Appendix C. Thermal conductivity experiment

APPENDIX C. THERMAL CONDUCTIVITY EXPERIMENT During the experiment some malfunctions were observed of the the guarded hot plate apparatus.

Approximately every 50 min periodic drops of voltage through the thermal pile were observed for most of the specimens. However, the short deviation seemed to have no or very little influence on the pattern of the continoiously stabilizing curve seen in Figure 135. Period of measurement for this specimen was 36 hours.

Longer term measurements for 13 days (Fig. 136) revelead not only the short voltage drops, but bigger scale disorders. After four noticeable voltage drops occurring within seven days, voltage did not stabilize at the same levels. This could lead to inaccurate results, especially for specimens measured for a shorter time. However, differences between stabilized conditions were small. 0,0005 V deviation would result in change of lambda value by the similar 0,0005 W/mK. In the end, results were not disregarded.

Voltage, V

Water - 38,6 kg/m3 0.0045 0.0044 0.0043 0.0042 0.0041 0.004 0.0039 0.0038 0.0037 0.0036 0.0035 0.0034 0.0033

Figure 134. Voltage through termal pile measurements for straw specimen rinsed with water (density â&#x20AC;&#x201C; 38,6 kg/m3).

Voltage, V

Water - 56,2 kg/m3 0.0045 0.0044 0.0043 0.0042 0.0041 0.004 0.0039 0.0038 0.0037 0.0036 0.0035 0.0034 0.0033

Figure 135. Voltage through termal pile measurements for straw specimen rinsed with water (density â&#x20AC;&#x201C; 56,2 kg/m3).

118

TECHNICAL UNIVERSITY OF DENMARK

Appendix D. Renovation

APPENDIX D. RENOVATION Renovation Temperature and humidity profiles for the pitched roof.

Figure 136. Temperature profile for pitched renovated roof

Figure 137. Humidity profile for pitched renovated roof

119

TECHNICAL UNIVERSITY OF DENMARK

Appendix D. Renovation Temperature and humidity profiles for the flat roof

Figure 138. Temperature profile for renovated flat roof

Figure 139. Humidity profile for renovated flat roof

120

TECHNICAL UNIVERSITY OF DENMARK

Appendix D. Renovation

Figure 141. Ground floor (accessed by Jörg Schöbel, 1-1-2016)

Figure 140 1Rst floor (accessed by Jörg Schöbel, 1-1-2016)

Figure 142. Attic (accessed by Jörg Schöbel, 1-1-2016)

121

TECHNICAL UNIVERSITY OF DENMARK

Appendix D. Renovation

122

Technical University of Denmark

APPENDIX E. Detailed measurements of the study cases in Crete.

Temperature measurements in LSC house during 11.08.2015 - 20.09.2015 40 38 36

Temperature, °C

34 32 30 28 26 24 22 20 18 16

Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

RelaƟve humidity measurements in LSC house during 11.08.2015 - 20.09.2015 85 80 75

RelaƟve humidity, %

70 65 60 55 50 45 40 35 30 25

Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

Moisture content measurements in LSC house during 11.08.2015 - 20.09.2015 20 19 18

Moisture content, g/kg

17 16 15 14 13 12 11 10 9 8 7

Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

CO2 concentraƟon measurements in LSC house during 11.08.2015 - 03.11.2015 1500 1400 1300

CO2 concentraƟon, ppm

1200 1100 1000 900 800 700 600 500 400 300 200 100 0

Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

CO2 concentraƟon measurements in STONE house during 20.09.2015 - 03.11.2015 1100 1000

CO2 concentraƟon, ppm

900 800 700 600 500 400 300 200 100 0

Outdoor

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom

APPENDIX E. Detailed measurements of the study cases in Crete.

Temperatures measurements in LSC and STONE houses during 20.09.2015 - 03.11.2015 32 30 28 26

Temperature, °C

24 22 20 18 16 14 12 10

Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom

Moisture content measurements in LSC and STONE houses during 20.09.2015 - 03.11.2015 17

16

15

Moisture content, g/kg

14

13

12

11

10

9

8

7

6

Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom

RelaƟve humidity measurements in LSC and STONE houses during 20.09.2015 - 03.11.2015 90

85

80

RelaƟve humidity, %

75

70

65

60

55

50

45

40

Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom

APPENDIX E. Detailed measurements of the study cases in Crete.

90

40

90

38

85

38

85

38

85

60

24

55

22

50

20

45

18

40

16

35

14

28

65

26

60

24

55

22

50

20

45

18

40

16

35

14

70

30 28

65

26

60

24

55

22

50

20

14

80

26

75

24

70

22

65

20 60 18

40

16

35

14

18 16

28

45

30

12

45

10

25

10

25

10

25

10

40

RelaƟve humidity

Temperature

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

RelaƟve humidity

Temperature

34

34

33

33

32

32

RelaƟve humidity

Temperature

28

33

27

27

32

26

26

25

25 24 23

36 35 34

31

30

29

24

29

29

28

23

28

28

27

27

27 26 25 24

Temperature, °C

30

Temperature, °C

Temperature, °C

31

24

26 25 24 23

21 20

22 21 20 19

23

22

22

22

21

18

18

21

21

17

17

20

20

18

16

19

19

16

18

18

17

15

15

17

17

14

14

16

16

13

13

12

12 11

20 19

16 15 14

15

13

14

14 13 12

12

13

11

11

12

10

10 0

11

11

10

20

30

10

10 0

10

20

30

40

50

60

70

80

90

0

100

10

20

30

LSC Living room

LSC West bedroom

40

50

60

70

80

90

Outdoor

LSC East bedroom

LSC Living room

LSC West bedroom

LSC East bedroom

90

90

85

85

85

80

75

75

70

70

65

65

70

80

90

100

30

40

50

60

70

80

90

100

0

10

20

30

40

50

60

70

80

90

100

CumulaƟve frequency, %

LSC Living room

LSC West bedroom

Outdoor

LSC Living room

LSC West bedroom

Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom

STONE Guest bedroom

RelaƟve humidity measurements 23.10 - 03.11

RelaƟve humidity measurements 20.09 - 03.11

90

90

85

85

80

80

75

75

70

70

80

75

60

55

RelaƟve humidity , %

RelaƟve humidity , %

RelaƟve humidity , %

50

20

Outdoor

65

55

10

CumulaƟve frequency, %

70

60

10 0

RelaƟve humidity measurements 20.09 - 22.10

90

80

60

STONE Guest bedroom

RelaƟve humidity measurements 11.08 - 19.09

RelaƟve humidity measurements 08.11 - 03.11

50

100

CumulaƟve frequency, %

CumulaƟve frequency, % Outdoor

40

CumulaƟve frequency, %

60

55

50

RelaƟve humidity , %

15

RelaƟve humidity , %

22

19

23

RelaƟve humidity

Temperatures measurements 20.09 - 03.11

29

37

30

25

Temperature

Temperatures measurements 23.10 - 03.11

31

26

RelaƟve humidity

28

37

25 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

CumulaƟve frequency, %

30

37

30

CumulaƟve frequency, %

29

38

35

0

31

39

38

40

10

30

39

38

45

12

31

40

35

50

32

39

35

55

22

32

40

36

60

24

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Temperatures measurements 20.09 - 22.10 40

36

0

CumulaƟve frequency, %

Temperatures measurements 11.08 - 19.09

Temperatures measurements 08.11 - 03.11

Temperature, °C

5

26

20

Temperature, °C

Temperature

0

CumulaƟve frequency, %

65

14

12

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

70

28

16

30 0

75

30

50

12

CumulaƟve frequency, %

80

32

18

30 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

85

55

12 0

90

38

34

Temperature, °C

26

30

Temperature, °C

28

65

RelaƟve humidity, %

30

32

70

85

30

75

40

36

RelaƟve humidity, %

32

70

Temperature, °C

32

34

75

90

32

80

Temperature, °C

34

75

36

80

RelaƟve humidity, %

34

34

RelaƟve humidity, %

36

95

RelaƟve humidity, %

40

80

Outdoor measurements 20.09 - 03.11

Outdoor measurements 23.10 - 03.11

90

36

Temperature, °C

Outdoor measurements 20.09 - 22.10

Outdoor measurements 11.08 - 19.09

Outdoor measurements 08.11 - 03.11 40

65

60

65

60

50

45 45

45

40

40

55

55

50

50

45

45

40

35 35

35

30 30

30

0 25

10

20

10

20

30

40

50

60

70

80

90

100

0

10

CumulaƟve frequency, % Outdoor

LSC Living room

LSC West bedroom

20

30

40

50

60

70

80

90

CumulaƟve frequency, % LSC East bedroom

30

40

50

60

70

80

90

100

0

10

20

Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

30

40

50

60

70

80

90

100

0

10

20

100

30

40

50

60

70

80

90

100

CumulaƟve frequency, %

CumulaƟve frequency, %

CumulaƟve frequency, %

25 0

40

40

25

Outdoor

LSC Living room

LSC West bedroom

Outdoor

LSC Living room

LSC West bedroom

Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

LSC East bedroom

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom

STONE Guest bedroom

STONE Guest bedroom

APPENDIX E. Detailed measurements of the study cases in Crete.

Moisture content measurements 11.08 - 19.09

19

19

19

18

18

18

17

17

17

16

16

15

15

14

14

12

15

13

14

Mixing raƟo, g/kg

Mixing raƟo, g/kg

13

16

13

12

17

17

16

16

15

15

14

14

13

13

Mixing raƟo, g/kg

20

Moisture content measurements 20.09 - 03.11

Moisture content measurements 23.10 - 03.11

Moisture content measurements 20.09 - 22.10

20

Mixing raƟo, g/kg

Mixing raƟo, g/kg

Moisture content measurements 08.11 - 03.11 20

12

11

12

11

12 11

11

11

10

10

10

10

10

9

9

8

8

7

7

9

9

9 8

8

8

7

7

7

6

6

10

20

30

10

20

30

40

50

60

70

80

90

100

0

10

CumulaƟve frequency, % Outdoor

LSC West bedroom

LSC East bedroom

20

30

40

50

60

70

80

90

CumulaƟve frequency, % LSC Living room

40

50

60

70

80

90

100

0

10

20

CumulaƟve frequency, %

6

0

6

6 0

Outdoor

LSC Living room

LSC West bedroom

LSC East bedroom

30

40

50

60

70

80

90

100

0

10

20

30

40

50

60

70

80

90

100

CumulaƟve frequency, %

CumulaƟve frequency, %

100 Outdoor

STONE Living room

STONE Bedroom upstairs

Outdoor

STONE Living room

STONE Bedroom upstairs

Outdoor

STONE Living room

STONE Bedroom upstairs

STONE Guest bedroom

LSC West bedroom

LSC East bedroom

STONE Guest bedroom

LSC West bedroom

LSC East bedroom

STONE Guest bedroom

LSC West bedroom

LSC East bedroom

LSC Living room

LSC Living room

LSC Living room

PrescripƟve model 20.09-03.11 (% of occupied hours) LSC STONE Living room West bedroom East bedroom Living room Bedroom upstairs Guest bedroom Class I 71,2 71,3 64,8 68,6 68,0 72,2 Class II 19,0 11,7 22,5 10,3 8,3 6,2 Class III 8,6 15,2 12,7 14,2 4,0 7,9 Out of range 1,2 1,9 0,0 6,8 19,8 13,6

AdapƟve model 10.23 - 11.03 LSC STONE Living room West bedroom East bedroom Living room Bedroom upstairs Guest bedroom Class I 4,2 0,0 0,0 0,0 0,0 0,0 Class II 77,2 8,1 36,2 0,4 0,0 0,0 Class III 18,2 80,4 54,3 11,6 3,7 7,4 Out of range 0,4 11,5 9,5 88,0 96,3 92,6

PrescripƟve model 09.20 - 10.22 LSC STONE Living room West bedroom East bedroom Living room Bedroom upstairs Guest bedroom Class I 81,8 89,4 77,3 90,5 90,5 95,1 Class II 12,6 6,6 18,8 9,5 9,3 4,9 Class III 4,0 2,4 4,0 0,0 0,3 0,0 Out of range 1,6 1,6 0,0 0,0 0,0 0,0

AdapƟve model 20.09-03.11 (% of occupied hours) LSC STONE Living room West bedroom East bedroom Living room Bedroom upstairs Guest bedroom Class I 52,5 29,7 43,7 11,5 12,5 13,9 Class II 39,8 27,6 25,2 26,6 26,4 27,1 Class III 7,1 38,2 24,5 35,8 32,2 34,6 Out of range 0,6 4,5 6,6 26,1 28,9 24,4

PrescripƟve model 10.23 - 11.03 LSC STONE Living room West bedroom East bedroom Living room Bedroom upstairs Guest bedroom Class I 41,8 20,6 29,8 7,6 5,3 8,3 Class II 36,9 26,1 33,2 12,5 5,5 9,9 Class III 21,3 50,8 37,0 54,0 14,3 30,2 Out of range 0,0 2,5 0,0 25,9 75,0 51,7

AdapƟve model 09.20 - 10.22 LSC STONE Living room West bedroom East bedroom Living room Bedroom upstairs Guest bedroom Class I 69,8 40,3 59,3 15,7 17,0 18,9 Class II 26,4 34,5 21,1 36,0 35,9 36,8 Class III 3,2 23,1 14,0 44,3 42,4 44,3 Out of range 0,6 2,0 5,6 4,0 4,8 0,0

RelaƟve humidity 20.09-03.11 (% of occupied hours) LSC STONE Living room West bedroom East bedroom Living room Bedroom upstairs Guest bedroom Class I 0,9 0,1 0,6 0,0 0,0 0,0 Class II 19,2 7,5 10,7 2,0 1,6 2,0 Class III 79,8 88,2 87,0 62,7 80,3 52,3 Out of range 0,1 4,1 1,7 35,4 18,0 45,8

RelaƟve humidity 09.20 - 10.22 LSC STONE Living room West bedroom East bedroom Living room Bedroom upstairs Guest bedroom Class I 1,3 0,2 0,8 0,0 0,0 0,0 Class II 23,6 10,2 14,6 1,4 2,2 1,4 Class III 75,1 85,6 82,4 62,4 89,3 56,6 Out of range 0,0 4,0 2,3 36,2 8,5 42,0

RelaƟve humidity 20.09-03.11 (% of occupied hours) LSC STONE Living room West bedroom East bedroom Living room Bedroom upstairs Guest bedroom Class I 0,9 0,1 0,6 0,0 0,0 0,0 Class II 19,2 7,5 10,7 2,0 1,6 2,0 Class III 79,8 88,2 87,0 62,7 80,3 52,3 Out of range 0,1 4,1 1,7 35,4 18,0 45,8

PrescripƟve model 11.08-19.09 (% of occupied hours) Temp range Living room West bedroom East bedroom Class I 21-25 3,4 8,8 7,6 Class II 20-26 19,9 14,8 21,9 Class III 18-27 29,4 21,8 30,3 Out of range 47,3 54,7 40,2

Thermal comfort (PrescripƟve model) 11.08 - 03.11 Temp range Living room West bedroom East bedroom Class I 21-25 73,0 68,5 65,6 Class II 20-26 18,4 12,4 20,7 Class III 18-27 8,5 18,2 13,7 Out of range 0,0 0,9 0,0

AdapƟve model 11.08-19.09 (% of occupied hours) Living room West bedroom East bedroom Class I 84,2 71,6 87,8 Class II 11,1 18,8 10,6 Class III 3,3 6,3 1,2 Out of range 1,4 3,3 0,4

Thermal comfort (AdapƟve model) 11.08 - 03.11 Living room West bedroom East bedroom Class I 66,4 48,0 62,8 Class II 27,4 23,5 18,4 Class III 5,3 24,6 14,7 Out of range 0,9 3,9 4,0

RelaƟve humidity 11.08-19.09 (% of occupied hours) RH% Living room West bedroom East bedroom Class I 30-50 12,5 17,8 5,8 Class II 25-60 82,2 58,4 66,3 Class III 20-70 5,3 23,8 27,9 Out of range 0,0 0,0 0,0

RH% Class I 30-50 Class II 25-60 Class III 20-70 Out of range

RelaƟve humidity 11.08 - 03.11 Living room West bedroom East bedroom 0,0 0,0 0,0 6,9 0,0 0,0 92,8 95,6 100,0 0,4 4,4 0,0

APPENDIX F. Detailed measurements of the study cases in Denmark.

Temperature, °C

Temperatures measurement during 15.11.2015 - 17.12.2015 31 29 27 25 23 21 19 17 15 13 11 9 7 5 3 1 -1 -3 -5

Outdoor

Konkyliehuset Living room

Konkyliehuset Upstairs

Spunk Huset Bedroom

Spunk Huset Livingroom

RelaƟve humidity measurement during 15.11.2015 - 17.12.2015 100 95 90 85

RelaƟve humidity, %

80 75 70 65 60 55 50 45 40 35 30

Outdoor

Konkyliehuset Living room

Konkyliehuset Upstairs

Spunk Huset Bedroom

Spunk Huset Livingroom

Moisture content content measurement during 15.11.2015 - 17.12.2015 2,6 2,4

Moisture content by volume, %

2,2 2 1,8 1,6 1,4 1,2 1 0,8 0,6 0,4 0,2 0

Outdoor

Konkyliehuset Living room

Konkyliehuset Upstairs

Spunk Huset Bedroom

Spunk Huset Livingroom

CO2 concentraƟon measurement during 15.11.2015 - 17.12.2015 1000 900

700 600 500 400 300 200 100 0

Outdoor

Konkyliehuset Living room

Konkyliehuset Upstairs

Spunk Huset Bedroom

Spunk Huset Livingroom

Daily moisture content fluctuaƟons

Daily relaƟve humidity fluctuaƟons

Daily temperature fluctuaƟons 30

5 4,5

15 10 5

Spunk Huset livingroom

Konkyliehuset livingroom Reference Bedroom

Konkyliehuset upstairs Reference LivingRoom

Spunk Huset bedroom

Konkyliehuset livingroom

Konkyliehuset upstairs

Spunk Huset livingroom

Reference Bedroom

Reference LivingRoom

Spunk Huset bedroom

outdoor

Konkyliehuset livingroom

Konkyliehuset upstairs

Spunk Huset livingroom

Reference Bedroom

Reference LivingRoom

Spunk Huset bedroom

15-12-2015

14-12-2015

13-12-2015

12-12-2015

11-12-2015

10-12-2015

09-12-2015

08-12-2015

07-12-2015

06-12-2015

05-12-2015

04-12-2015

03-12-2015

02-12-2015

01-12-2015

30-11-2015

29-11-2015

28-11-2015

27-11-2015

26-11-2015

25-11-2015

24-11-2015

23-11-2015

22-11-2015

21-11-2015

20-11-2015

15-12-2015

14-12-2015

13-12-2015

12-12-2015

11-12-2015

10-12-2015

09-12-2015

08-12-2015

07-12-2015

06-12-2015

05-12-2015

04-12-2015

03-12-2015

02-12-2015

01-12-2015

30-11-2015

29-11-2015

28-11-2015

27-11-2015

26-11-2015

25-11-2015

24-11-2015

23-11-2015

22-11-2015

21-11-2015

20-11-2015

19-11-2015

18-11-2015

16-11-2015

17-11-2015

outdoor

19-11-2015

0 15-11-2015

15-12-2015

14-12-2015

13-12-2015

12-12-2015

11-12-2015

10-12-2015

09-12-2015

08-12-2015

07-12-2015

06-12-2015

05-12-2015

04-12-2015

03-12-2015

02-12-2015

01-12-2015

30-11-2015

29-11-2015

28-11-2015

27-11-2015

26-11-2015

25-11-2015

24-11-2015

23-11-2015

22-11-2015

21-11-2015

20-11-2015

19-11-2015

18-11-2015

16-11-2015

15-11-2015

17-11-2015

outdoor

1 0,5

0 0

2 1,5

18-11-2015

2

3 2,5

17-11-2015

4

20

4 3,5

16-11-2015

RelaƟve humidity, %

6

Moisture content, g/kg

25

8

15-11-2015

10

Temperature, °C

RelaƟve humidity, %

800