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PLEA 2003 – The 20th Conference on Passive and Low Energy Architecture, Santiago – CHILE. 9-12 Noviembre 2003-10-07 Paper Code C12. Page 1 of 6

The Pallet House Cristian Suau Ibáñez Architect Ph.D. - MSc E-mail: cristian.suau@usa.net

ABSTRACT. This study has been developed in HDM, Lund University and it focuses on the use of passive technique to achieve indoor thermal comfort in experimental houses in arid coastal lands in the Atacama Desert, Chile. Computer simulations indicates that indoor comfort conditions may improve by simple passive techniques that included the use of recycled and local material for thermal storage/insulation, shading devices and orientation of openings. The case study –Pallet House- formulates a life cycle model by the recycling of timber pallets as constructive units with lightweight materials using for low-income houses. Conference Topic : Light Architecture, Passive Techniques, Experimental Design in Arid Lanscapes Keywords : Architecture in Desert, Recycling Pallet Boards, Light Materials

DESERT AND BIOCLIMATIC ARCHITECTURE Often characterized as an "extreme" environment, the arid lands provide considerable inputs of solar energy and acceptable levels of human comfort. The opportunities for utilizing natural energies -such as solar radiation and across ventilation- are among the many passive systems and design strategies which is especially pronounced in an arid climate. Bio-climatic architecture adapts to climatic and environmental conditions in order to achieve a situation of indoor thermal comfort with design elements and minimazing the use of complex mechanical systems. It retrieves and combines ancient or local techniques and new ones. This architecture considers the environmental impact of all the processes implied in housing. From materials that do not produce toxic waste and do not consume much energy, utilizing a proper use of passive techniques, building location and embodied energy. Bioclimatic or passive architecture is closely related to housing design to get energy efficiency because it reduces impact of energy consumption on it (see figure 1).

On one hand, the geography of most arid regions of the world has dictated a predominant traditional use of earthen and light materials in construction. For dwellers in arid settlements, earthen, local and disposal material has always been affordable, inexpensive or even free and also particularly used as thermal storage. On another hand, population in arid lands mostly establish in port-cities or fertile valleys, where new waves of dwellers –i.e.: low-income immigrants- mostly utilice recycled building material to build temporal shelters and mainly leftover materials such as pallets boards. This is the case study of lightweight houses in the port of Iquique, located in the Atacama Desert, Chile (see figure 3). With sparse population and low rates of development, the Atacama Desert has typically received little attention from planning professionals in Chile. This means that standard building norms are predominantly adapted for non-desert conditions. Figure 2.

Latitude of the Atacama Deset

Climatic map of the Americas and the location of Capricorn tropic. According to UNCHS, a house built primarily with local material consumes 1/3 less embodied energy than a house made primarily with manufactured materials.

BACKGROUND Figure 1. Design of the Pallet House using lightweight and recycled material. This experimental house uses low energy-content materials and applies climatic design principles such us windows orientation, thermal properties of materials, and shading devices. Suau, 2002.

Design for recycling of disposed materials may highly reduce the energy in slight houses set up along emerging port cities, particularly in the northern coast of Chile. Selecting timber boards such as pallets constitute one of the structural and thermal materials.

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CLIMATE OF THE ATACAMA DESERT The coast desert or Costal Range of Northern Chile begins at Arica and ends in Antofagasta (latitude 30°S approach), the main mining copper port. The arid climate of Northern Chile is the product of a unique synthesis of oceanographic, atmospheric and topographic conditions. Solar radiation in this zone is very strong, and may reach 5.5 Kwh/m² x day on a horizontal surface (during December and February). The average of ambient relative humidity is 71%. Summer daily temperature fluctuation (from December until March) is about 5.8°C, and the average temperature is within the range of thermal comfort. In this latitude, precipitation has never been recorded and seldom rains (4 mm of annual rainfall, 2002). So, the coastal arid climate in the city of Iquique (BWn) is considered moderate hot during the summer with an average annual maximum temperature of 25.60°C. The average annual daytime temperature is 22.25°C. Iquique is located in the latitude 20°10’S and longitude 70°13W. Finally, prevailing winds mostly come

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For housing in hot-arid weather, cooling is the most important for the greater part of the year, but in cool season both certain heating is required or additional internal gains: 1. Form. In the climatic case, traditional and modern buildings have a tight shape instead of courtyard or patio. 2. Materials. The particular climate of coastal deserts such as Iquique does not have high changes between day and night the Inner Atacama Desert. So, light materials may be utilized in order to gain a comfortable indoor climate. 3. Solar orientation. Is the most important factor and openings facing north and south are suitable. During wintertime, an accurate dimension and orientation of glazed openings may minimize cooling. During summertime, shading devices in the windows may reduce overheating specially during afternoon. 4. Ventilation. Prevailing southern winds may be caught and addressed by airflow devices in other to get passive cooling in summertime. IQUIQUE (BWn) latitude 20,19°S; long. 70Latitude:

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A portable timber board type stringer pallet is the most commonly used pallet in the United States and the Pacific countries, with the most common size being 120 x 100 cm².

Image of a traditional Aymara house made by earthen materials in the Inner Atacama Desert (highaltitude desert), 2002.

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According to sizes, load properties and type of timber’s components and also as affordable material, the Pallet House only utilizes one standard model called stringer pallet. It is the most commonly used pallet, with the most common size being 120 x 100 cm². A stringer pallet is called that because it uses "stringers," which support the unit load. The stringers are the boards, typically 2 x 4's or 3 x 4's, sandwiched between the top and bottom deck boards (See figures 4A and 4B).

CLIMATIC GUIDELINES FOR THE PALLET HOUSE

Radiation

Aerial view of Iquique city in the Atacama Desert, Chile. This coastal arid town is featured as a rainless zone.

Temperature

Figure 3.

from S (June and July indicate SW winds) and secondary winds always come from SSW and has an average speed of 4 m/sec (See climatic data in figure 6). The intensity of solar radiation during the winter is relatively high even do maritime clouds reduce overheating. These conditions make the surrounding of Iquique an almost ideal location for buildings that might achieve thermal comfort in the winter by employing solar energy.

Relative humidity

The Pallet consists of a portable wooden platform (thin single or double-sided strips of wood nailed or screwed in a regular timber frame) used to facilitate the handling of stacked goods by storage or moving. The pallets are manufactured with hardwoods, softwoods, and plywood, to the degree of dryness required for your specific application. The main characteristic of pallets is that it allows to use air space in addition to floor space, reducing warehousing.

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Climatic data of Iquique city. 2002.

Bioclimatic data of Iquique according to Givoni diagram


Nevertheless, thermal insulation is recommended specially in the roof because it is the surface, which absorbs the most solar radiation during summer. Mainly in deserts, “a lightweight and insulated envelope reduces overheat transfer, mainly during winter but needs heavy internal elements for thermal storage”. Therefore heavy internal materials for thermal storage are not required because of the short thermal variation between summer and winter in the coastal Atacama Desert. The climatic guidelines for building design in this coastal climate gathers both the creation of an envelope housing system, sealed as far as possible against the leak of energy and also recuperate the traditional building legacy of “floating roof” houses. In this envelope should be openings, allowing controlled passages of natural energy especially south winds during the 4 seasons. According to Givoni´s climatic diagram, any building should take into account that the indoor thermal comfort varies from 18°C to 25°C. So, an annual climatic data of Iquique reveals that it only during wintertime needs internal thermal gains –mostly July- and in summertime -mostly February- needs cross ventilation (See figure 7). So, the Pallet House’s climatic design follow these recommendations: A. Plan must be oriented north –South and should also be a regular layout; B. No airflows are required; C. Openings should be medium size: 25% - 40%; D. Light walls with short time-lag (low thermal capacity); E. Light roof well insulated. However, waterproof and outdoor spaces are not required.

PROBLEM The wooden houses in Iquique city was built during 1880 using lightweight timber systems and a constructive detail called “balloon frame” and readapting this model according to this particular climate. Climatically, the building shape consists of several shading devices such as veranda, floating timber roof and large windows mostly facing north and south (See figure 9). Nevertheless, the rapid economical growth of this city and the lack of urban strategies during ‘90 has eroded the former scale and proportion of the urban fabric, wrecking or seriously damaged the traditional blocks and plotting. Also new wave of immigrants is set up in the periphery without basic sanitary and public facilities (See figure 8). By use of passive techniques in design and form of lightweight buildings, we reduce the auxiliary heating, ventilating and/or lighting load. A purely passive solar building uses no additional energy to collect solar heat. Appropriate passive solar designs are specific to a given climate, site, building function and use. In case of Iquique city, they are influenced by the prevailing cultural and architectural tradition of wooden constructions.

Figure 8. Another urban approaches towards the emerging

HYPOTHESES Passive techniques such as orientation, light and well-insolated walls and shading devices can improve housing indoor comfort. However, the impact of these factors can vary according to location, local weather, the user’s perception of climatic comfort and the internal gain of the inner spaces. Recycling of disposed wood material for building and structural housing aims (plus technological added valued) in marginal urban environment starts an innovative process for modular low-income housing units and explores new ecological, technical and architectural properties and the particular use of wood in an arid environment. The use of recycled pallets as structure and roof protection with earthen isolation is low in embodied energy and they constitute an environmental and economic saving reducing the purchased energy by the improvement of the indoor climatic comfort within low-income houses. They also limit the environmental impact of housing in arid coastal lands.

METHOD The research methods used at HDM, Lund University, introduced to a range of passive tools and techniques that can be used for studying the built environment in a region with distinct biophysical characteristics, such as the coast of Atacama Desert. Methods are focused on architectural and environmental issues at the level of the individual building divided in two volumes. • Thermal simulation for prediction and analysis of building performance. • Microclimatic measurements of indoor and outdoor parameters • Techniques for building analysis • Evaluation of construction materials and their properties: lightweight wood boards and wall/roof/floor building elements/components as well. About how to improve indoor climate in this experimental Pallet-House, the preliminary design will be first compared with traditional analytical tools and computer simulations (i.e.: Givoni’s bioclimatic chart, Mahoney tables and DEROB-LTH models) and then new improvements by climatic design will be suggested. Refering to modern analytical tools, DEROB-LTH or Dynamic Energy Response of Building’s model is an efficient computer tool consisting of modules that analyse internal and external factors for the indoor climate of the building such as orientation, solar radiation, indoor and surface’s temperature and also heating and cooling loads. Finally, the constructive part constitutes an additional research and it will focus on the relation between the context and the use of local and recycled building materials that can be founded and manufactured on-site. This building stage has not been developed yet; however, there are some constructive experiments (See figure 10).

slums around Iquique port and the reuse of disposal pallets boards as shading device’s fences. Source: Suau, 2001.

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I. SIMULATION ONE. Basecase of Pallet House in Summer and Winter using woodwool, foamed concrete and rammed earth slabs in walls, floors and roof . Openings facing North – South. With shading devices. Figure 11. Climatic model of Simulation 1 (volumes 1 and 2). DEROB modeling. Source: Suau archives, 2002.

Figure 9. An urban detail of a wooden block in Iquique city. The picture refer to the existing wooden row houses and a street profile of the historical area in Iquique city. Chile, 2002.

VOLUME 2

Figure 10. First year’s students reusing pallets boards as shading

VOLUME 1

pavilion in the Atacama Desert. Source: Workshop Suau, 2001.

RESULTS. CASE STUDY OF PALLET HOUSE This case study consists of a two-storey house, a cube of 6.00 (W) x 6.00 (L) x 6.00 (H) m³. The prototype has been tested in a semi-urbanized plot in Iquique city, occupied by temporal and informal houses. So, this unit has two main volumes (V1 and V2). In order to simplify this simulation, internal walls have not been considered and the overall thermal properties of this building are focused in the envelope o membrane: external walls, floors and roof. There are two openings made by single glazed windows (one pane each) which dimension is 3.00 (W) x 3.00 (H) m². Finally, in order to control the indoor comfort in this house, was introduced a system of pivoted shading devices over glazed openings (See figure 1). Climatically, the first parameter is that the solar orientation of the building is the key for affordable thermal comfort. Nevertheless, a north-south facing elevation is needed only for establishing the openings, and it should be medium sized enough to enable thermal comfort. Desirable transfer of energy, allowing for heating the house by passive solar energy in the winter and cooling it in the summer by nighttime ventilation, should be done only through and by the openings and upper vents. The external walls, floors and roof in the PalletHouse should be built according to this climatic guidelines that follow: First, the inner layer of the pallet wall should be only using well-insulated light materials like wood wool¸light concrete or earthen slabs like rammed earth, which constitute also an integral part of the storage mass of the experimental building. On the external side of walls/roof and floors another insulating layer or seal is going to be tested, consisting of 15 mmthick plasterboards. This additional layer is added to the chosen material using special plasterboard. In order to prevent heating of the wall as a result of high absorbtance or exposure of high solar radiation the external wall surfaces and roof must be whitened. On short, the basecase study was tested according to the outline design and taking into account these parameters in three comparative simulations in summer and winter : A. Material changes in walls/floors/roof; B. Window orientation (N – S versus E- W coords) and C. Shading devices.

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A Comparative Simulation 1 in Summer (February). Basecase of Pallet House in Summer using woodwool, foamed concrete and earthen slabs in walls, floors and roof. Openings facing N–S and shading devices. 30

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Figures 11 a,b. Diagrams of indoor temperature with the chosen building materials in volume 1 and 2 .

B Comparative Simulation 1 in Wintertime (July). Basecase of Pallet House in Winter using woodwool, foamed concrete and rammed earth slabs in walls, floors and roof. Openings facing North – South and shading devices. 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10

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Figures 11 c,d. Diagrams of indoor temperature with the chosen building materials in volume 1 and 2 .

II. SIMULATION TWO. Basecase of Pallet House in Summer and Winter using woodwool, foamed concrete and rammed earth slabs in walls, floors and roof. Openings facing East – West and with shading devices.

VOLUME 2

VOLUME 1

Figure 12. Climatic model of Simulation 2 (volumes 1 and 2). DEROB modeling. Source: Suau archives, 2002.


A Comparative Simulation 2 in Summertime (February). Basecase of Pallet House using woodwool, foamed concrete and rammed earth slabs in walls, floors and roof. Openings facing East – West and shading devices. V1

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Figures 13 c,d. Diagrams of indoor temperature with the chosen building materials in volume 1 and 2 .

CONCLUSION

Figures 12 a,b. Diagrams of indoor temperature with the chosen building materials in volume 1 and 2 .

B Comparative Simulation 2 in Wintertime (July). Basecase of Pallet House using woodwool, foamed concrete and rammed earth slabs in walls, floors and roof. Openings facing East – West and shading devices. 25

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Figures 12 c,d. Diagrams of indoor temperature with the chosen building materials in volume 1 and 2 .

III. SIMULATION THREE: Basecase of Pallet House in Summer and Winter using woodwool, foamed concrete and rammed earth slabs in walls, floors and roof . Openings facing North – South. No shading devices Figures 13. Climatic model of Simulation 3 (volumes 1 and 2). DEROB modeling. Source: Suau archives, 2002.

VOLUME 2

A.

Material Changes in Pallet House.

In these chosen comparative simulations, the order of the layers in the envelope were fundamental to underscore. For instance, if the thermal insulation were placed on the inside of the wall, only the thermal resistance of the wall would remain constant because it consists of an addition of the thermal resistances of all the layers. Three different materials have been applied in the basecase: woodwool, rammed earth (initially adobe) and foamed concrete slabs. Most building materials used in arid lands significantly reduce their life gaps due to exposure to solar radiation, which dries them out and makes extreme fluctuations of their surface temperature between daytime and nighttimes. Replacing the insulation on top of the sealing layer –plaster boardreduces the temperature fluctuations to which it is exposed. Therefore, following the same considerations used in walls, insulation should be placed on the external side of the cover. The chosen roof section for the Pallet-House consists of a structure of stringer pallet added by a outer sealing layer of plaster board (See figure 14). Figure 14. Section panel. Stringer pallet + wood wool or earthen slabs in walls and roof. Derob test, 12.2002 outer 1

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4 inner 1. Top deck board 2. Plaster board 15mm 3. Wood wool / earthen slab 4. Bottom deck board 20mm 5. Stringers 2’x4’

A Comparative Simulation 3 in Summer (February). Basecase of Pallet House using woodwool, foamed concrete and rammed earth slabs in walls, floors and roof. Openings facing N – S and no shading devices. 40

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Figures 13 a,b. Diagrams of indoor temperature with the chosen building materials in volume 1 and 2 .

B Comparative Simulation 3 in Wintertime (July). Basecase of Pallet House in Winter using woodwool, foamed concrete and rammed earth slabs in walls, floors and roof. Openings facing North – South and no shading.

The openings of a building in arid lands can either supply a significant proportion of the heating required in the winter or may be a "hole" in the envelope through which there is an uncontrolled passage of energy. In the summer the openings can be, on one hand, well insulated, allowing for a light increase of the indoor temperature. It depends on their design, building orientation and the use of shading devices in the building’s openings. Comparing simulation 1 and 3, the design of the windows should maximize solar gain in the winter and minimize such gain in the

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summer. Following a north-south orientation, openings design should also minimize the penetration of hot air into the building during the warm hours of the summer and of cool air during the winter, whilst allowing massive ventilation on cool summer nights. The building's significant thermal storage should contribute to balance the large daily temperature fluctuations typical of the desert, and also should increase the building's thermal lag time (See figures 15 and 16). Protecting the interior of the Pallet House from heating by solar radiation incident on the windows during the summer (assuming that the rest of the envelope is sealed against energy penetration) is very important for affordable thermal comfort in this house. The windows facing east and west present the most difficulties.

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but also in wintertime. The solution is to install exterior blinds or other movable or sliding shading mechanisms that can minimise solar radiation from windows. Since the radiation heating the structure during the summer is diffuse and irregular, shutters or “pivoted brise-soleil” (see figures 1 and 17) are required in all window orientation. However, the basecase assumed that all outer surfaces of this devices were whitened. Under these considerations, the climatic design of the Pallet House should consider a number of small southern vents in each volume. In both volumes there are relatively large openings facing to north – south axis. These openings can be used for cooling the house in the summer in spite of their thermal performance in the winter.

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Figure 15. Passive climatic design. Ground level of the Pallet House. Openings facing north-south. Source: Suau archives, 2002.

Figure 17.

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Passive climatic result from the lateral elevation of the Pallet House taken from the simulation 1. Shading devices are facing north (left side) and wind collectors are facing south (right side). Source: Suau archives, 2002.

REFERENCES Figure 16. Passive climatic design. Upper level of the Pallet House. Openings facing north-south. Source: Suau archives, 2002.

C. Use of Shading Devices in Openings In light and well insulated structures like the Pallet House, it is possible to calculate with a high degree of accuracy the necessary size of the windows based on average monthly or dayly external temperatures in the coldest month (June). It is possible to calculate the expected heating load of the house in order to decide which portion should be supplied by the sun (a primarily economic decision), and to combine the size of the windows with the use of shading devices. However, functional requirements fostered the idea to keep medium windows facing north-south which meant do not alter their original dimensions in the Pallet House. Based on other climatic studies in arid lands is that permanent overhangs, shutters and other shading elements over glazed openings are very useful under this climatic context. The comparison between simulation 1 and 3 (with and without shading devices) showed that the first simulation achieves enormous indoor thermal comfort in

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[1]

Rosenlund, Hans. 1995. Design for Desert. Lund University, Housing Developing & Management Unit, Thesis 7. [2] Lesser, Heinz. 2000. Arquitectura en Iquique. El Sistema Constructivo Balloon-Frame (Architecture in Iquique. Balloon-frame as a Building System), Editorial Facultad de Arquitectura, Universidad de Chile. Revista de Arquitectura 11. [3] Schmitz-Gunther, Thomas. 1999. Living Space: Sustainable Building & Design, Koneman Inc., Cologne. [4] Suau, Cristian. 2001. Alvar Aalto and his Wooden Pavilions. Polytechnical University of Catalonia (UPC), School of Architecture (ETSAB), Barcelona. Doctoral thesis.

The Pallet House  

Light Architecture, Passive Techniques, Experimental Design in Arid Lanscapes

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