Drin chulakasyena

Design guidelines for or towards free-running high-rise housing - in the hot and humid urban environment of Bangkok MSc Sustainable Environmental Design Dissertation Project 2015-16

AA E+E Environment & Energy Studies Programme Architectural Association School of Architecture Graduate School

Drin Chulakasyena September 2016

Authorship Declaration Form AA E+E ENVIRONMENT & ENERGY STUDIES PROGRAMME ARCHITECTURAL ASSOCIATION GRADUATE SCHOOL

PROGRAMME:

MSc Sustainable Environmental Design 2015-2016

SUBMISSION:

Dissertation project

TITLE:

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

NUMBER OF WORDS:

18,736 (excluding references & figures)

STUDENT NAME:

Drin Chulakasyena

DECLARATION: “I certify that the contents of this document are entirely my own work and that any quotation or paraphrase from the published or unpublished work of others is duly acknowledged.”

Signature(s):

Date: 16 September 2016

Acknowledgements I would like to thank to my teaching staff of Sustainable and Environmental design: Simos Yannas, Paula Cadima, Jorge Rodriguez Alvarez, Klaus Bode, Nick Baker, Gustavo Brunelli, Bryon Madras, Mariam Kapsali and Herman Calleja for the very helpful and stimulating classes, tutorials and presentations. I acknowledge and appreciate their encouragement and their enthusiasm and passion in communicating their knowledge.

I would especially like to thank to my personal tutor Paula Cadima, for her help and patience with all my difficulties in this dissertation and her gentle prompting to continually explore new ideas.

Last but not least, I would like to thank my parents, William & Natedao O’Brien, Dune Chulakasyena, for their unconditional support over the years and for providing me with the opportunity to attend this programme.

Abstract Bangkok is one of the world’s hottest and most humid cities, and is experiencing rapid growth in the construction of new high rise residential developments, which are very largely dependent on air conditioning to provide acceptable thermal comfort to their occupants. This research seeks to identify and explore the key issues of shading, ventilation, building form and materials that influence internal temperature, leading to the establishment of guidelines towards free-running high rise buildings in this climate. Consideration is also given to making balconies, a ubiquitous but underutilised feature, more usable.

It was found that a combination of fixed horizontal shading devices, vertical shading devices and adaptive horizontal louvres could effectively address issues of excessive direct and diffuse solar radiation. Re-imagining building forms to create opportunities for cross ventilation, combined with large window openings, matched in areas on opposing walls, and opened and closed with regard to temperature differentials, greatly improved temperature reduction through ventilation. A cavity wall construction of heavy concrete with an outer timber skin, separated by an air gap, improved the thermal performance of the façade. Specifying materials of high thermal mass in living areas and low thermal mass in bedroom areas further enhanced user comfort. Combining all elements into an optimised model and testing its performance showed it to provide a viable basis for free-running designs for high rise residential buildings in the target context.

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

Table of Content

Page

List of Figures……………………………………………………………………….…………...iv List of Tables…………………………………………………………………………………….vi

1

Introduction……………………………………………………………………2 1.1 Problems observed in existing high rise buildings in Bangkok…………………..3 1.2 Objective and scope of dissertation …………………………………………………3 1.3 Research questions ……………………………………………………………………...4 1.4 Methodology …………………………………………………………………………......4 1.5 Structure ……………………………………………………………………………………4

2

Context of Bangkok………………………………………………………….6 2.1 The nature of development in the chosen area…………………………………….7 2.2 Regulations and trends ………………………………………………………………….9 2.2.1 Setback 2.2.2 FAR Bonus system 2.2.3 Balconies in Bangkok 2.2.4 Construction materials 2.3 Weather data and climate analysis ………………………………………………….12 2.3.1 Temperature 2.3.2 Solar radiation 2.3.3 Relative humidity 2.3.4 Wind 2.3.5 Rain 2.3.6 Daylight 2.4 Comfort band for people in Bangkok………………………………………………….17 2.5 Conclusion ………………………………………………………………………………….18

3.

Theoretical background……………………………………………………..20 3.1 Thermal comfort ……………………………………………………………………………21 3.1.1 Feature A: accepted comfort rage i. ii. iii.

Air speed Humidity Mean radiant temperature

3.1.2 Feature B: adaptive opportunities 3.2 Cooling strategies ………………………………………………………………………….23 3.2.1 Solar control i. ii. i

External fixed shading devices External operable shading devices

Chapter 2 – Context of Bangkok

iii.

Internal operative shading devices

3.2.2 Natural ventilation i. ii.

Building scale Unit scale

3.2.3 Other cooling strategies i. ii.

Vegetation Water elements

3.3 Daylighting …………………………………………………………………………….…......31 3.4 Materials …………………………………………………………………………….………...31 3.5 Balconies ……………………………………………………………………………………...33 3.6 Conclusions ………………………………………………………………………….……….34

4.

Precedents……………………………………………………………………….36 4.1 Vernacular architecture ……………………………………………………………………37 4.1.1 Open layout linked by walkways and orientation 4.1.2 Verandahs/buffer zones 4.1.3 Air-permeable walls 4.1.4 Window openings 4.1.5 Materials 4.1.6 Roofs 4.1.7 Raised floor 4.2 Contemporary buildings …………………………………………………………………...39 4.2.1 TTDI building (Kuala Lumpur - Malaysia) 4.2.2 The Met (Bangkok) 4.2.3 No. 1 Moulmein Rise (Singapore) 4.2.4 Happy lnad Townhouse and Allzone Headquarters (Bangkok) 4.3 Conclusion ……………………………………………………………………………………41

5.

Fieldwork …………………………………………………………………………44 5.1 Interviews ……………………………………………………………………………………..45 5.1.1 The Rhythm building 5.1.2 The U-Delight 5.2 Spot measurements …………………………………………………………………………47 5.3 Data logger …………………………………………………………………………………...49 5.4 Conclusions …………………………………………………………………………………...51

6.

Analytic work…………………………………………………………………….54 6.1 Indoor analysis …………………………………………………………………………….…55 6.1.1 Shading devices ii

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

i.

ii.

Fixed shading device a) Result for fixed horizontal shading devices b) Results for fixed horizontal + vertical shading devices c) Additional observation on depth of horizontal shading Adaptive shading device a) Thermal analysis b) Daylighting analysis

6.1.2 Building form 6.1.3 Natural ventilation i. ii.

Opening size Using windows to control ventilation

6.1.4 Materials i. ii. iii.

Walls Ceilings and floor Furnishings

6.1.5 Occupancy i. ii.

Increased occupancy Interaction between thermal mass and day time window operation

6.2 Balcony ………………………………………………………….…………………………...77 6.2.1 6.2.2

7.

Dimensions of balcony Thermal comfort on balconies

Research outcomes……………………………………………………………84 7.1 Proposed guidelines ………………………………………………………………………..85 7.2 Subject for further research ……………………………………………………………….90

8.

Conclusions………………………………………………………………………92

9.

References...……………………………………………………………………..96

10.

Appendices………………………………………………………………………102

iii

Chapter 2 – Context of Bangkok

List of figures Chapter 2 Figure 2.1 Some of the new high-rise residential building in Bangkok from year 2012-2016(After: http://skyscrapercenter.com/city/bangkok and http://www.realist.co.th/) (p.7) Figure 2.2 Examples of high-rise residential building in Bangkok (Source: http://www.prakard.com/) (p.8) Figure 2.3 Examples floor plan (Source: http://www.apthai.com and http://www.ananda.co.th) (p.8) Figure 2.4 Examples of room types (Source: http://www.apthai.com and http://www.ananda.co.th) (p.8) Figure 2.5 Permitted height of buildings (p.10) Figure 2.6 an example of ground floor (Source: http://www.grandu.co.th) (p.10) Figure 2.7 Two examples of “FAR Bonus” system (Source: City Planning Department Bangkok Metropolitan Administration) (p.10) Figure 2.8 Examples of high-rise residential building with balconies in Bangkok (From left to right: Ideo Q Ratchathewi, Ideo Q phayathai, Lumpini CondoTown, sansiri-pyne) (Source: http://www.prakard.com/) (p.11) Figure 2.9 Thailand’s location (p.12) Figure 2.10 Bangkok’s location (p.12) Figure 2.11 Bangkok (Don-Muang airport station) weather data (Source: Meteonorm 7.0) (p.14) Figure 2.12 Bangkok (Don-Muang airport station) sun path diagram and solar radiation (Source: Meteonorm 7.0) (p.14) Figure 2.13 Bangkok (Don-Muang airport station) wind rose diagram (Source: Meteonorm 7.0) (p.16) Figure 2.14 Average rainfall (mm) from year 2000 to 2012 (Source: www.worldweatheronline.com) (p.16) Figure 2.15 Contour plots of global horizontal illumininance for Bangkok (Source: Chirarattananon, et al. 2001) (p.16) Figure 2.16 Bangkok (Don-Muang airport station) weather data with the comfort band (Source: Meteonorm 7.0) (p.17)

Chapter 3 Figure 3.1 Shading device with horizontal and vertical planes (Source: Koch-Nielson, 2002) (p.24) Figure 3.2 Perforated screen walling which can admit light and breezes while keeping out the sun and providing security.

(Source: Littlefield ed., 2008) (p.24) Figure 3.3 Example of operable shading device (source: www.archdaily.com) (p.26) Figure 3.4 Adaptive shading device – Horizontal louvre (Source: Yanas 2015) (p.26) Figure 3.5 Adaptive shading device – Perforated screen (Source: Goncalves, 2015) (p.26) Figure 3.6 Wind velocity profiles (Source: Szokolay, 2008) (p.28) Figure 3.7 Wind pattern (Source: Oedterle, 2001) (p.28) Figure 3.8 Air speed with different configurations, with and without projection, and at different directions (Source: Givoni, 1994) (p.28) Figure 3.9 Alcoves projecting slightly from the room (Source: Givoni, 1994) (p.28) Figure 3.10 Window types relevant to high rise building in Bangkok (Source: CIBSE, 2005) (p.28) Figure 3.11 Stack ventilation studies - sections (Source: Prajongsan, 2011) (p.30) Figure 3.12 Inlet and outlet control the wind direction (Source: Koch-Nielson, 2002) (p.30) Figure 3.13 Daylight studies (Source: CIBSE ,1999) (p.32) Figure 3.14 The daylight factor profile of a side-lit room (Source: Baker and Steemers, 2002) (p.32) Figure 3.15 Operation of a heavyweight house (Source: Szokolay, 2000) (p.32) Figure 3.16 Cobogo - opaque envelop using high thermal mass materials (Source: Yannas, 2015) (p.32) Figure 3.17 Incorporated/Inset balconies (Source: Neufert, 2002) (p.33) Figure 3.18 Offset Balconies (Source: Neufert, 2002) (p.33) iv

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

Chapter 4 Figure 4.1 Summary of the keys feature in vernacular Thai house.(After: Cholasuek; 2010, Sirichanchuen, 2015) (p.38) Figure 4.2 Optimal orientation and distance between buildings (Source: Cholasuek, 2010) (p.38) Figure 4.3 Window design of Thai vernacular architecture (Source Cholasuek, 2009) (p.38) Figure 4.4 TTDI building (Source: Tantipat, 2011) (p.40) Figure 4.5 The Met, 30th floot plan (Source: Ali, 2013) (p.40) Figure 4.6 No.1 Moulmein Rise - section detail of monsoon window (Source: CTBUH, 2009) (p.40) Figure 4.7 Happy land Townhouse front façade and floor plan (Source: Tedkajohn, 2013) (p.42) Figure 4.8 Allzone Headquarters front façade and floor plan (Source: Tedkajohn, 2013) (p.42) Figure 4.9 Wire mesh floors located between the façade and the building (Source: Tedkajohn, 2013) (p.42)

Chapter 5 Figure 5.1 The Rhythm building - Apartment M (Source: http://www.apthai.com) (p.46) Figure 5.2 View from the living room (Apartment M) (p.46) Figure 5.3 The U-delight building - Apartment S (Source: http://www.grandu.co.th) (p.46) Figure 5.4 Curtain on the balcony (Apartment S) (p.46) Figure 5.5. (Apartment S) temperature (p.48) Figure 5.6 (Apartment S) surface temperature (p.48) Figure 5.7. (Apartment S) Surface temperature (p.48) Figure 5.8. (Apartment S&M) Spot measurements – Daylight (p.48) Figure 5.9 Lobby area on the ground of Rhythm building (left) and U-Delight building (right) (p.48) Figure 5.10 (Apartment M) Data loggers (3-6 July) (p.50) Figure 5.11 (Apartment S) Data loggers (8-11 July) (p.50)

Chapter 6 Figure 6.1 Calibrated simulations (p.56) Figure 6.2 Base case (simplified version) (p.56) Figure 6.3 0.5m fixed shading devices - Left Horizontal, right Horizontal and Vertical combined (p.57) Figure 6.4 Results for fixed horizontal shading device (south orientation) (p.59) Figure 6.5 Results for fixed horizontal shading device (east orientation) (p.59) Figure 6.6 Results for fixed horizontal shading device (north orientation) (p.60) Figure 6.7 Results for fixed horizontal shading device (west orientation) (p.60) Figure 6.8 Sun path diagram for Bangkok (p.61) Figure 6.9 Shadow mask diagrams for fixed horizontal shading device (left), horizontal and vertical combined (right) (p.61) Figure 6.10. Comparison between each orientation of yearly transmitted solar radiation results for fixed horizontal and horizontal + vertical shading device (p.62) Figure 6.11.Types of adaptive shading devices (p.63) Figure 6.12. Results for adaptive shading devices (South orientation) (p.65) Figure 6.13 Results for adaptive shading devices (East orientation) (p.65) Figure 6.14 Results for adaptive shading devices (North orientation) (p.66) v

Chapter 2 – Context of Bangkok Figure 6.15. Results for adaptive shading devices (West orientation) (p.66) Figure 6.16 Daylight analysis for adaptive shading devices (p.68) Figure 6.17 Comparison of various building forms (p.70) Figure 6.18 Comparison of various building forms and their effect on internal temperatures (p.70) Figure 6.19 various configurations of openings (p.72) Figure 6.20 Air changes per hour with various configurations of openings (p.72) Figure 6.21 The effect of selected patterns of ventilation on internal temperature (p.72) Figure 6.22 Performance of base model compared to optimised model (p.74) Figure 6.23 Optimised model comparing two occupants overnight with two all day + four at weekends (p.76) Figure 6.24 Optimised model with windows open all day compared to windows closed from 10.00 – 17.00 (p.76) Figure 6.25 Recommened dimension of balcony for 3-4 people (Source: after Neufert, 2002) (p.78) Figure 6.26 Minimum comfortable width for dining area. (Source: after Neufert, 2002) (p.78) Figure 6.27 Examples of balcony layout with tables and chairs (p.78) Figure 6.28 Variations wingwall configurations. (p.79) Figure 6.29 Results of wind flow perpendicular to the panels. (p.81) Figure 6.30 Results of wind flow at 450 to the panels. (p.82)

Chapter 7 Figure 7.1 An example of proposed building form (p.86) Figure 7.2 proposed fixed shading devices (p.86) Figure 7.3 proposed adjustable fixed shading devices (p.86) Figure 7.4 Examples of external façade protection (p.86) Figure 7.5 An examples of proposed design for cross-ventilation (total area of 3m2 opening for both side) (p.88) Figure 7.6 An examples of proposed design floor plan for one bedroom unit (p.88)

List of tables Table 3.1 Air velocity and effect on thermal comfort (Source: Lechner, 2009, p.281) (p.22) Table 3.2 Recommendations concerning the cooling effect of elevated air velocities for residential buildings in hot-humid climates (for sedentary activities and light clothing) (Source: Prajongsan, 2011). (p.22) Table 6.1 Base case parameters summary (simplified version) (p.56) Table 6.2 Specification summary for daylight simulations (p.68)

vi

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

1

Chapter 1 - Introduction

CHAPTER 1

Introduction

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

The city of Bangkok continues its rapid growth of recent years and this is driving the construction of high rise residential buildings. Bangkok is one of the world’s hottest and most humid cities and almost all these new developments are very largely dependent on air conditioning to provide acceptable thermal comfort to their occupants. While there has been a deal of attention to improving the environmental aspects of design of very low cost residential housing in Bangkok, less attention seems to have been given to the lower and mid-market demographic that is driving the construction of the majority of high rise residential development in the city. This presents both a challenge and an opportunity to develop guidelines for high rise residential buildings that will reduce both the immediate and long term environmental impact of this construction, while simultaneously providing comfortable and sustainable accommodation for the occupants.

1.1 Problems observed in existing high rise residential buildings in Bangkok High rise developments in Bangkok are commonly designed with single aspect apartments and double load corridors, in either I or L shape, with large glazed areas, no shading devices and with a balcony inset into the façade of every unit. As a consequence the potential for cross ventilation is very limited.

Most of this housing replicates cold-climate models with sealed facades and relies very heavily on air conditioning which engenders a wide range of environmental impacts. This is at odds with traditional living patterns in the tropics, where light winds, year-round balmy weather, and fairly constant temperatures make outdoor living desirable. At the same time the obvious constraints of high rise construction, and of air pollution and noise in the city, limit the potential for the outdoor lifestyle that previous generations enjoyed. That said, there seems clear potential to design better performing buildings that would both improve environmental performance and work in better harmony with the climate.

Balconies are an almost omnipresent feature of high rise residential buildings in Bangkok and offer the greatest opportunity for connecting the occupants with the exterior environment. They can provide a transition space between exterior and interior that can be used for relaxation and contemplation. They can be used for cooking, eating, socialising, pets, pot plants and hanging baskets – and more. But research and observation by the author (Chulakasyena, 2016) shows that the design of most existing balconies is such that they are little used other than for storage, drying clothes and as a location for air conditioning condenser units.

A combination of high demand and limited regulatory control can result in buildings whose design focus is on fast and low cost construction, often with lip service at best to environmental issues. As the market matures there is opportunity to promote the benefits of a greater focus on sustainable design, delivering not only better environmental performance but long term cost savings.

1.2 Objective and scope of dissertation The aim of this dissertation is to develop design guidelines for or toward free running high-rise residential buildings in Bangkok, while maintaining or improving occupant comfort and their satisfaction with their dwellings. The dissertation will also consider the functionality of balconies.

3

Chapter 1 - Introduction

1.3 Research questions I. II. III. IV. V. VI.

To what extent can vernacular architecture offer insights that could be applied to improving the design of contemporary high rise residential building?

What are the most effective forms of external shading – within the constraints of local building regulations -- which still permit natural ventilation, and how do they vary according to the orientation of the façade?

What are the most effective ways to achieve desirable levels of natural light without excessive solar heat gain?

How can cross ventilation be achieved in a range of representative building/apartment layouts?

What are the construction materials and finishes that will deliver the best combination of cost, thermal and visual performance?

What are the main characteristic balconies need to provide good levels of functionality for typical apartments?

1.4 Methodology The following sequence is used. Clarification of the issues of concern, study of the context, climate, local trends in construction and building design, and research into the applicable regulatory constraints. Literature review relating to all issues that might impact on the research questions. Study of precedents of both vernacular and contemporary solutions. Fieldwork informed by initial research, encompassing observations, measurements and interviews. Analytic work using software simulations to explore potential solutions to problems and improvements to current practices. Assessment of all the research and simulation outcomes leading to development of design guidelines.

1.5 Structure Chapter 2 Context of Bangkok Chapter 3 Theoretical background Chapter 4 precedents Chapter 5 Fieldwork Chapter 6 Analytic work Chapter 7 Research outcomes Chapter 8 Conclusions

4

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

5

Chapter 2 – Context of Bangkok

CHAPTER 2

Context of Bangkok

6

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

2.1 The nature of development in the chosen area The continuing rapid expansion of the city of Bangkok has brought with it major problems of traffic congestion and accompanying vehicle-related pollution. This in turn is driving high rise housing development (Fig. 2.1).

According to Ratanawaraha (2013) the percentage of housing development in Bangkok categorised as high rise has been increasing strongly from 2008, when it was around 12%, to around 51% in 2012. Ratanawaraha’s research suggested that more and more young single people are migrating to the city. This group are more attracted to accommodation within high-rise buildings than low rise as the accommodation is commonly smaller, less expensive and requires minimal maintenance. Around 44 new buildings (around 24,800 units) were constructed in the year 2013 (REIC, 2016).

A combination of high demand and limited regulatory control can result in buildings whose design focus is on fast and low cost construction, often with lip service at best to environmental issues. A majority of new high rise developments are of simple, conventional forms (Fig. 2.2), commonly with an internal plan providing apartments on either side of a central corridor (Fig. 2.3). As a consequence the apartments have windows in only one façade and no potential for cross ventilation. Air conditioning is almost universal, and the design of most buildings is such that air conditioning is the only way of achieving and maintaining thermal comfort. It seems very likely that the assumption that air conditioning will be used means in many cases that little or no serious thought is given to passive methods of temperature control.

The internal design of apartments varies in terms of size and design, according to their target market, but the majority are intended for people living alone, for couples or at most for small families of 3-4 people. As a result most buildings will comprise a mixture of unit sizes which are mainly of 3 types: studio, one bedroom and two bedroom (Fig. 2.4). One bedroom units are the most popular as they meet the core needs of young singles and couples while providing the most attractive compromise between price and living space. For these reasons the focus of this research will be on one bedroom apartments

Figure 2.1 Some of the new high-rise residential building in Bangkok from year 2012-2016 (After: http://skyscrapercenter.com/city/bangkok and http://www.realist.co.th/)

7

Chapter 2 – Context of Bangkok

Figure 2.2 Examples of high-rise residential building in Bangkok (Source: http://www.prakard.com/)

Figure 2.3 Examples floor plan (Source: http://www.apthai.com and http://www.ananda.co.th)

Figure 2.4 Examples of room types (Source: http://www.apthai.com and http://www.ananda.co.th) 8

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

2.2 Regulations and trends 2.2.1 Setback The Bangkok Comprehensive Plan (2013) provides guidelines for the development of land in Bangkok. Two key metrics are Floor Area Ratio (FAR) and Open Space Ratio (OSR).

The FAR is the ratio of the total floor area of all floors in the building to the size of the plot of land in which the building is located. The OSR is the ratio of the total area of uncovered space to the total floor area of all buildings on the same plot of land. As the result of these two regulations, the bigger the building, the bigger open spaces that it needs to provide. There are also regulations relating to Building Setback defined as the distance from the boundary of the plot to the edge of the structure of the building (including any overhang). This is mainly for safety reasons, to enable access by a fire engine. One of the key regulations relates to the permitted height of buildings. The building may be as high as twice the distance between the building and the site boundary of the site opposite (based on the façade adjacent to the widest road) (Fig. 2.5).

The combined effect of these regulations commonly forces developers to locate their structure in the middle of the site and/or far back from the main road to allow the building to be as high as possible. As a result, new build development in Bangkok is commonly surrounded by open space, especially near to main roads. Such areas may be used as communal space or for small low-rise mixed use buildings (Fig 2.6).

However, the setback regulations have the negative effect of discouraging any protrusions from the building, including offset shading devices and overhangs, as they effectively reduce the permitted maximum height of the building and permitted of the building foot print.

2.2.2 FAR Bonus system “FAR Bonus” (Fig. 2.7) is a system that increases the permitted floor area if certain criteria are met.

Two of the FAR bonuses relate respectively to the provision of green open space and “green building construction”), meeting one of the four levels approved by the Thai Green Building Institute. The former arguably tends to render balconies slightly more desirable as more green space enhances the outlook from balconies, especially for the lower level units, and the latter potentially influences all aspects of building design and construction.

9

Chapter 2 – Context of Bangkok

Figure 2.5 Permitted height of buildings

Figure 2.6 an example of ground floor (Source: http://www.grandu.co.th)

Figure 2.7 Two examples of “FAR Bonus” system (Source: City Planning Department Bangkok Metropolitan Administration)

10

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

2.2.3 Balconies in Bangkok Even through there are no regulations requiring the provision of balconies, in practice the majority of residential developments will include balconies in their design for both functional (as described in section 1.1) and aesthetic reasons. Papamanoli (2005) described balconies as “a fundamental architectural element of all residential buildings�.

Figure 2.8 Examples of high-rise residential building with balconies in Bangkok (From left to right: Ideo Q Ratchathewi, Ideo Q phayathai, Lumpini CondoTown, sansiri-pyne) (Source: http://www.prakard.com/)

The design of balconies in Bangkok (Fig. 2.8) tends to fall into two categories: the inset (loggia, portico or brise-soleil) type where the balcony space is incorporated within the building boundary, and the offset type. Glazed balconies are observed in some buildings but are uncommon.

2.2.4 Construction materials The construction industry in Thailand still relies intensively on manual labour and the use of locally available materials, which are much less costly than imported alternatives. Concrete and brick are the most common materials used in high rise residential building (National Statistical Office of Thailand, 2010) due to low cost, simplicity of construction, high durability and the familiarity of the workforce with these materials.

For some low cost buildings, concrete slabs are used for both internal and external walls as they offer a fast and cheap solution with high thermal mass properties and high thermal conductivity (around 0.8 -1.8 W/mK), albeit with poor sound proofing qualities.

In some mid cost buildings, lightweight concrete blocks are also used. These provide higher insulating properties (thermal conductivity around 0.3-1.2 W/mK) together with lighter weight.

Windows are commonly single glazed with aluminium frames, with high u-values.

Timber is the most popular finish for the floors of living spaces. Ceramic tiles are commonly used in bathrooms, kitchens and balconies.

11

Chapter 2 – Context of Bangkok

2.3 Weather data and climate analysis

Figure 2.9 Thailand’s location

Figure 2.10 Bangkok’s location

Bangkok is situated on a deltaic plain at latitude 13.44 N and longitude 100.3 E (Fig. 2.9-2.10) and is on average 1.5m above sea level. Bangkok has a tropical wet and dry/ savanna climate (Köppen-Geiger classification: Aw) with three main seasons: cool and dry (mid Oct-mid Feb), hot and wet (March-May) and warm and wet (May-Oct).

12

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

2.3.1 Temperature Bangkok city experiences high air temperatures for most of the year. The average mean dry-bulb temperature ranges from 28.1 °C to 30 °C, with an average maximum between 30.7 °C and 32.0 °C (Fig 2.11). With an average diurnal fluctuation between day and night of around 5 -10 k, this suggests potential for applying passive cooling solutions by thermal inertia.

2.3.2 Solar radiation Solar radiation in Bangkok is high (both direct and diffuse) all year round (Fig. 2.11). The most common sky condition in Bangkok is overcast. The high frequency of overcast sky conditions increases the overall amount of diffuse solar radiation, which as a result is very high, ranging from 4.3-5.8 kWh/m² daily (Fig. 2.11). This is almost double the level of direct radiation, throughout the year, and highlights the need for special attention to be given to protection from diffuse radiation.

The data (Fig. 2.12) show that vertical solar radiation affecting east and west orientations is high almost all year round (between 2.5-3 kWh/m3). For north orientations the peak is from May to July and for south orientations the peak is during the cool period from mid-October to mid-February.

This pattern of radiation suggests that the main facades of the building should face north and south to minimise solar impact.

2.3.3 Relative humidity The relative humidity in Bangkok is between 68% and 80% (Fig. 2.11). It is known that high humidity limits evaporation, increasing skin wetness and causing discomfort. One of the most effective ways to deal with humidity is ventilation and air motion since these enable convective cooling of the skin.

13

Chapter 2 – Context of Bangkok

Figure 2.11 Bangkok (Don-Muang airport station) weather data (Source: Meteonorm 7.0)

Figure 2.12 Bangkok (Don-Muang airport station) sun path diagram and solar radiation (Source: Meteonorm 7.0)

14

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

2.3.4 Wind The prevailing wind direction during hot and warm period is from the south to south-west. During the cool and dry period the prevailing wind is from the north to north-east (Fig. 2.13) with an average unobstructed wind speed in Bangkok throughout the year of 2.2 m/s (Meteonorm 7) .

Givoni (1994) has suggested that ventilation, and by implication the orientation of the building faรงade, should be the primary consideration as solar control can be implemented by means of more easily applied shading devices and therefore allows greater flexibility in implementation.

From the data it can be concluded that the optimum orientation for a building in Bangkok in relation to wind would be with its main facades facing north and south to maximise the potential for natural ventilation. This matches the recommendations for solar radiation.

2.3.5 Rain During rainfall the outdoor temperature usually drops dramatically. Figure 2.14 shows that most of the hot periods have high levels of rainfall. This suggests potential to use the drop in temperature to help achieve thermal comfort by natural ventilation, but account would need to be taken of the strong winds that commonly accompany rainfall in the area.

2.3.6 Daylight Daylight in Bangkok averages 11 hours per day yearly, largely between 6.30 -17.30. Light levels are around 10-20 Klux from 7-8 am, 90 -100 Klux around noon and 10-15 Klux between 5-6 pm (Fig 2.15).

Thai people eat their evening meal early by international standards and are thus able to eat in daylight.

15

Chapter 2 – Context of Bangkok

Figure 2.13 Bangkok (Don-Muang airport station) wind rose diagram (Source: Meteonorm 7.0)

Figure 2.14 Average rainfall (mm) from year 2000 to 2012 (Source: www.worldweatheronline.com)

Figure 2.15 Contour plots of global horizontal illumininance for Bangkok (Source: Chirarattananon, et al. 2001) 16

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

2.4 Comfort band for people in Bangkok It is well established that in free running buildings people can accept a wider range of thermal conditions than in a controlled environment. Studies by Taweeken (2013) found that the comfort zone for Thai people in air conditioned environments was in the range of effective temperatures of 24 °C - 27 °C at an air velocity of 0.2 m/s, with relative humidity between 50%-70%. But the studies of Busch (1992) show that 80% of Thai workers in naturally ventilated buildings are satisfied with an upper temperature of 31 °C. This corresponds with the studies by Jitkhajornwanich (2006) in even more extreme climate conditions (the hot and rainy season) which identified an acceptable range of 25.6 - 31.5 0C at relative humidity of 62.2-90% for the adaptive comfort band (for occupants of houses of traditional vernacular design).

EN 15251 is an adaptive model. Thermal preference is a result of both physiological factors and expectations based on climate-cultural determinants. These variations can be due to geographical differences or “habits” developed over time by spending time in certain environments and is applicable to free running buildings.

The thermal comfort criteria set out in EN 15251 will be used for assessment purposes as they correspond closely to the findings of most of the studies in Bangkok while providing a formula to use as follows.

Running Mean (Trm): weighted running mean of the daily mean external temperature (i.e. gives more importance to recent temperatures).

Trm = (1-α)*Ted-1 + α*Trm-1 Recommended α=0.8 (equivalent to 1 week acclimatisation).

Ted-1 = daily mean external temperature for the previous day The formula is used to find thermal neutrality (Tn) for each period. The comfort band was defined by adding + and – 3 0K to the calculated Tn, which would result in a PPD (percentage of people dissatisfied) of 10% (applicable to new buildings).

The formula excludes the effect of the wind movement and how it can affect thermal comfort. In real life situations if significant levels of natural ventilation can be achieved the number of hours that fall within the comfort zone will be higher.

The thermal comfort band in relation to monthly average temperature is shown in Figure 2.16

Figure 2.16 Bangkok (Don-Muang airport station) weather data with the comfort band (Source: Meteonorm 7.0) 17

Chapter 2 – Context of Bangkok

2.5 Conclusion The building regulations in Bangkok create some unfortunate influences on building design. To achieve the maximum floor area developers commonly choose a compact, monolithic form: a rectangular cuboid or L-shape. Conventional internal plans result in little or no potential for cross ventilation. Both the regulations and the prioritisation of low construction cost over building performance discourage the incorporation of shading devices. At the same time, saleability is enhanced by large areas of glazing (which optimises desirable views), but exacerbate problems of solar heat gain and glare.

Balconies are a common and desirable feature and the local building regulations have a side effect of creating enhanced views from balconies, especially on the front facades of buildings.

How balconies can be rendered more comfortable and thus more usable will be explored in section 6.2.

Construction materials and methods tend to be very conventional. The higher cost of more innovative materials, often imported, and the unfamiliarity of the local workforce with their use, continue to favour traditional concrete and brick.

The year round hot and humid climate of Bangkok, with high levels of both direct and diffuse solar radiation, presents significant but not insuperable challenges in achieving acceptable levels of thermal comfort. If the current universality of air conditioning is to be challenged it must be demonstrated that free running is both achievable and economically viable. It is noteworthy that it is not necessary for a free-running building to achieve the same temperatures as an air conditioned one: the thermal comfort zone for people in naturally ventilated buildings is wider than in air conditioned ones.

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

19

Chapter 3 – Theoretical background

CHAPTER 3

Theoretical background

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

3.1 Adaptive Thermal comfort Thermal comfort is a state of mind and in many cases very subjective. It is influenced by culture, previous experiences, the surroundings, user activities, user clothing, body shape, age, gender and many more factors. According to Olesen and Brager (2004) thermal comfort is “that condition of mind which expresses satisfaction with the thermal environment”. While the conditions required for thermal comfort vary from person to person, falling within the comfort zone should be the goal of thermal design as it represents condition where the majority of the people feel comfortable (Lechner, 2009) Fanger, in a paper presented at a BRE conference in 1993, stated that the best buildings for overall comfort have should have two key features, as defined and explained in more detail below.

3.1.1 Feature A: “the building should provide conditions that are within the accepted comfort range (so people do not need make frequent adjustments)” (Fanger, 1993) Thermal comfort in indoor and semi-indoor spaces (transitional spaces) is affected by the environmental factors of air temperature, air velocity, solar radiation, relative humidity and radiant temperature (Cohen, 1997).

Lechner (2009) has stated that there are three key factors that we can modify to help improve the thermal comfort: air speed, relative humidity and mean radiant temperature. i.

Air speed

According to Givoni (1994) natural ventilation is the most effective way to minimise the physiological effect of heat in a hot and humid climate.

Lechner (2009) shows the impact of wind velocity on effective temperature. Air speeds of 0.2 m/s and 0.4 m/s are shown to be suitable for houses as both are considered comfortable and reduce the effective temperature by 1 °C - 2 °C (Table 3.1).

It has also been shown by numerous researchers that air movement helps lower the perception of temperature (Table 3.2), but at the same time excessive ventilation can potentially cause discomfort: an air velocity of 0.8m/s might start to pick up loose paper and light object (Reynolds, 1992) ii.

Humidity

High humidity can decrease human tolerance to hot temperatures as the human body can evaporate less sweat at high humidity levels and this can lead to discomfort (Brunelli, 2015). High humidity can cause problems in relation to comfort at both high and low temperatures.

Even though the ASHRAE standard suggests a comfortable upper limit of relative humidity of 30 - 60%.

But the adaptive model allow lower and higher humidity, depending on the other factors involved in thermal comfort such as airflow and clothing.

One of the most effective ways to reduce relative humidity is ventilation, which has an important influence on thermal comfort (Taweekun, 2013). iii.

Mean radiant temperature

This term describes the radiant environment for a point in space, the result of the combined effect of surface temperature and angle of exposure: the sums of all short and long wave radiation fluxes (both direct and reflected) to which the human body is exposed. This is one of the most important meteorological parameters governing human energy balance and thermal comfort.

The mean radiant temperature can be increased or decreased by varying the surface area, the angle to heat sources (sun or surface temperatures) and the ability of the materials both to absorb energy and to emit stored energy.

All the above factors will impact on the thermal comfort of the occupants of the building.

21

Chapter 3 – Theoretical background

Table 3.1 Air velocity and effect on thermal comfort (Source: Lechner, 2009, p.281)

Air Speed (m/s) 0.05 0.2 0.4 0.8 1

Equivalent Reduction (K) 0 1.1 1.9 2.8 3.3

Temperature

Effect on comfort Stagnant air, slightly uncomfortable Barely noticeable but comfortable Noticeable and comfortable Very noticeable but acceptable Upper limit for air conditioned space, good air velocity for natural ventilation

Table 3.2 Recommendations concerning the cooling effect of elevated air velocities for residential buildings in hot-humid climates (for sedentary activities and light clothing) (Source: Prajongsan, 2011).

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

3.1.2 Feature B: “people in the building should have facilities to alleviate discomfort quickly when it occurs” (Fanger, 1993) Building occupants need to be able adjust their environmental conditions if they fall outside ranges they find comfortable. These controls can be in a form of adaptive opportunities such as blinds, shading devices or openable partitions, or mechanical means of delivering cooling or heating. These topics will be discussed in more detail in the section 3.2 “Cooling strategies”.

3.2 Cooling strategies In hot and humid climates the two primary methods of improving thermal comfort are effective ventilation and the provision of shading devices (Givoni, 1994).

Givoni (1994) has suggested that ventilation, and by implication the orientation of the building façade, should be the primary consideration. However, this project is addressing high-rise residential buildings where the footprint of the building and orientation are often dictated by site constraints and where flexibility in the orientation of facades may be limited as a result. Natural ventilation is certainly a key factor to be addressed but it is logical to prioritise the reduction in heat gain over its subsequent reduction.

3.2.1

Solar control

The major source of solar radiation transmitted through to a building interior is via the glazing (Yannas, 1994). High rise developments commonly incorporate large windows both to take advantage of views and to provide good opportunities for ventilation. Effective control of solar radiation therefore involves the use of shading devices to shield glazed areas. At the same time, however, care needs to be taken to avoid or minimise any negative effect on the views through the shaded windows, and to balance reducing undesired heat gain with maintaining sufficient levels of natural light and natural ventilation.

An opaque shading device, either horizontal or vertical (Fig. 3.1) can be effective in protecting against direct solar radiation. However, direct solar radiation is not the only source of solar heat gain in urban areas: for lower floors, reflected long wave solar radiation should also be taken into consideration where units might subject to reflections from close adjacent exposed surfaces (Holger Koch-Nielsen, 2002). Higher floors will be affected more by diffuse solar radiation from the sky during cloudy conditions. Lower floors also can be affected by reflections from nearby structures. To protect against diffuse solar radiation, a perforated three-dimensional screen with a defined minimal thickness can provide an effective solution as it is effective at blocking radiation from a wide range of different angles (Fig. 3.2).

According to Givoni (1994) there are three main types of shading device: i. ii. iii.

‘

23

External fixed shading devices.

External operable shading devices.

Internal operable shading devices.

Chapter 3 – Theoretical background

Figure 3.1 Shading device with horizontal and vertical planes (Source: Koch-Nielson, 2002)

Figure 3.2 Perforated screen walling which can admit light and breezes while keeping out the sun and providing security.

(Source: Littlefield ed., 2008)

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

i.

External fixed shading devices

External shading (Fig 3.1) is preferable for very large windows as it obstructs the incident radiation before it reaches the building surfaces (Yannas, 2000).

There is wide consensus as to the effectiveness of horizontal shading devices for north and south facing windows. However, there is not the same level of agreement with regard to the shading of east and west facing windows in a tropical climate, with supporters of both horizontal shading and vertical fins. Givoni (1994) suggests that fixed horizontal overhangs are more effective than vertical fins, although claiming that the only way eastern and western window can be shaded fully effectively is by a “frame” consisting of horizontal and vertical fins at an oblique angle of 45 0 towards the south.

One can conclude that vertical shading devices will be more effective during early morning and late afternoon when the sun is at a low altitude, whereas during the middle of the day horizontal shading is essential (Erell, 2011).

Koch-Nielsen (2002) set out some key points for shading devices in hot climates. They should be: a) Placed on the outside of an opening. b) Made of light and reflective materials, to avoid absorption and re-radiation of the heat through an opening. c) Made of materials with low heat storage capacity (to ensure rapid cooling). d) Designed to prevent reflection onto any part of the building openings. e) Designed such that hot air is not trapped. ii.

External operable shading devices

There are two potential functional advantages of adjustable external shading over fixed external shading. Occupants can be given the opportunity to adjust levels of solar radiation and daylighting to suit their own preferences. Additionally or alternatively, a building control system can be used to automatically adjust external shading to a theoretically optimum setting in any given combination of conditions. In either case the settings would be expressed on the façade of the building, creating dynamic transitions and varying the appearance of the building (Fig 3.3). The disadvantages of external operable shading devices include their cost, complexity, requirement for maintenance and long term durability.

User adjustable external shading devices can be designed to deliver high levels of solar protection without the same degree of concern over negative effects on views, if the user can themselves choose to prioritise solar protection or views and daylight levels (Fig 3.4-3.5).

iii.

Internal operable shading devices

These have the lowest efficiency in terms of thermal control as they intercept the sun’s rays after the rays have passed into the interior of the building, so would not be recommended as a main source of solar protection in a very hot climate such as Bangkok. Internal shading devices are, however, very effective and convenient for controlling levels of daylight.

25

Chapter 3 – Theoretical background

Figure 3.3 Example of operable shading device (source: www.archdaily.com)

Figure 3.4 Adaptive shading device – Horizontal louvre (Source: Yanas 2015)

Figure 3.5 Adaptive shading device – Perforated screen (Source: Goncalves, 2015)

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

3.2.2

Natural ventilation

Ventilation can help reduce foul air, and humidity, which has an important influence on thermal comfort (Taweekun, 2013). It has also been shown by numerous researchers that air movement helps lower the perception of temperature (discussed in detail in section 3.1.1{i}).

Physical forced generation ventilation is affected by two main forces (Givoni, 1998): a) A temperature difference between indoors and the outdoors (thermal, or Thermosyphonic, Force) b) Wind flow against the building (wind pressure force) The flow rate due to thermosyphonic flow is rather small in a hot climate, even with cross ventilation: wind pressure force is more relevant in hot/tropical climates (Givoni, 1998). i.

Building scale

The mean wind speed increases with height (Szokolat, 2008). The graph above (Fig. 3.6) shows that as the height increases from 0-50 meters the wind speed rises: at 50 meters (16th floor level) the wind speed is almost double that at 6 meters (2nd floor level). Oedterle (2001) identifies three patterns of wind flow around a high rise building (Fig. 3.7). The first is a horseshoe vortex effect at the base of the building where wind flowing off the windward face exerts a downward pressure and curls round on both sides of the building. The second is airflow around the body of the building, which may or may not be constant depending on the shape and consistency of the faรงade. The third is top flow, where a large volume of air flows upwards and over the roof at the top of the building. These different wind effects at various heights mean that thought could usefully be given to varying the form of the building accordingly at different heights. This would be a useful subject for further research but detailed analysis of these effects falls outside the scope of this paper. (For further information see Appendix A). ii.

Unit scale

A large floor to ceiling height can help provide a reservoir for warm air above head height (Cohen, 1997). In traditional Thai architecture high roofs with no ceilings were used to allow hot air to rise up and ventilate out through gaps between the tiles. Applications of the same principle are theoretically possible in high rise buildings.

A room with windows in one wall only is likely to experience poor ventilation, especially where the indoor-outdoor pressure gradient across the opening is very small. A method of improving ventilation in this situation is to provide two lateral windows with a vertical projection (wing wall) between them.

A projection placed downwind of a window create a high pressure in front of it. A projection upwind of a window creates a strong suction behind it. This phenomenon, increases the airflow in the room, as shown in experiments by Givoni (1988) (Fig. 3.8). The practical application of this principle can take a number of forms, including an alcove projecting slightly out from the room, recesses or projecting porches (Fig. 3.9) Types of window opening (Fig 3.10) also effect airflow patterns. Sliding windows have restricted opening areas but require no extra space when open. By comparison, top hung, side hung, pivot and louvre windows provide larger open areas. Vertical side hung and pivot windows can create a wing-wall effect to guide airflow into the room. This would theoretically be useful for units on lower floors where there is less opportunity of benefiting from direct wind flow than on higher floors.

However, pivot windows are incompatible with mosquito netting, which is a crucial requirement in tropical climates, especially at lower heights where mosquito numbers are higher. According to the American Mosquito Control Association, in general mosquitoes that bite humans prefer to fly at heights of less than 7.6 meters, but in Singapore mosquitoes have been found in apartments 21 stories above ground. The installation of insect netting or glazing is therefore essential, at all building heights.

Top hung windows can be used to catch the downward or upward wind flow that is generated when wind is blocked by a building (or protect against it). Louvre windows function effectively irrespective of the wind direction, unlike side hung or casement windows. They can be angled to direct air flow to the ceiling, moving hot air that has risen upwards. They can be opened during rainfall without 27

Chapter 3 – Theoretical background

Figure 3.6 Wind velocity profiles (Source: Szokolay, 2008)

Figure 3.7 Wind pattern (Source: Oedterle, 2001)

Figure 3.8 Air speed with different configurations, with and Figure 3.9 Alcoves projecting slightly from the room without projection, and at different directions (Source: Givoni, 1994) (Source: Givoni, 1994)

Figure 3.10 Window types relevant to high rise building in Bangkok (Source: CIBSE, 2005)

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

water ingress. They have an effective opening area. But their infiltration levels when closed are higher than other window types.

Studies by Sobin (1980) in relation to opening type suggest that a landscape windows (windows that are wider than their height) create greater wind speeds than portrait ones.

When designing openings in building envelopes it is also important to consider safety and privacy, and protection from noise, pollution and biting insects. Insect netting may reduce airflow by 30%, even using the best, smooth nylon screen (Szokolay, 2008).

Studies by Prajongsan (2011) show the benefits of stack ventilation in creating cross ventilation in high rise residential buildings (Fig. 3.11). Careful attention needs to be paid to the pressures at inlet and outlet vents and the interrelationship between height, vent size, inside and outside temperatures and differential pressures. A poorly designed system could result in hot air from lower floors exhausting into higher floors rather than flowing out of the top of the stack (CIBSE 2005). Goncalves (2016) cautioned that if the height of an atrium designed to create a stack ventilation effect is more than 12 storeys high it will not function effectively. While stack ventilation does offer potential benefits, its complexity compared to the implementation of simple cross ventilation suggests it may not be worth pursuing for high rise residential buildings.

Studies by Tantasavasdi et al (2001) suggest that, for cross-ventilation scenarios where there is a consistent prevailing wind direction, a better opportunity for ventilation can be achieved if the inlet on the side of the prevailing wind is bigger than the outlet. But a relatively large opening on the windward side results in lower air velocities compared with a smaller opening facing the wind. Small opening on the windward side and large opening on the leeward side will create higher air velocities and more changes of air, but also poorer distribution of air throughout the room (Fig. 3.12). Baker (2015) states that best results are achieved when the total area of inlet and outlet are the same.

Where natural ventilation cannot be effectively achieved through any of the above methods, one of the most efficient methods of increasing air movement (and thus thermal comfort) is the use of a ceiling or freestanding fan (Baker, 2007).

3.2.3 i.

Other cooling strategies Reducing cooling loads through vegetation/evapotranspiration

Vegetation in an urban setting affects the overall environmental performance through microclimatic improvement. In may take the form of grass, green roofs, green walls, trees, shrubs etc.

Vegetation on facade walls helps in reducing their surface temperature and ameliorates outdoor comfort by decreasing the radiant load, while simultaneously reducing heat transmission to the interior. However, vegetation on a wall may block long wave and convective heat loss, according to Givoni (1998). Further considerations are the aesthetic benefits of vegetation on a facade, and the potential of vegetation to filter noise and pollution.

Vegetation can moderate solar heat gain through evaporation and help filter out dust and pollution, but some types of vegetation may also obstruct wind flow.

Vegetation may be used to advantage in spaces such as balconies and outdoor and semi outdoor communal areas. However, care needs to be given to the selection of vegetation in such areas as many species grow very fast in a tropical climate and this can give rise to problems of overgrowth and troublesome maintenance. ii.

Water elements

Water elements in outdoor spaces can help improve microclimatic conditions through evaporative and latent cooling. However, opportunities for effective evaporative cooling are limited in a hot and humid climate, as there is limited potential for evaporation due to the initial high humidity, and evaporation may raise humidity to unacceptable levels. Nonetheless, if there is a constant wind flow evaporative cooling may still be effective, for example on the roof and balconies of high rise buildings.

29

Chapter 3 – Theoretical background

Figure 3.11 Stack ventilation studies - sections (Source: Prajongsan, 2011)

Figure 3.12 Inlet and outlet control the wind direction (Source: Koch-Nielson, 2002)

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

3.3 Daylighting The design of solar controls will have a great influence on the daylight performance of the building.

The need is to ensure a balance between blocking/reducing solar radiation while maintaining levels of daylight that ensure the visual comfort of the occupants without the need for artificial light during the daytime. Minimising the need for artificial lighting also reduces heat gains from the lighting to the interior – although the use of LED technology hugely reduces both the energy use and heat gain from lighting.

Multi-aspect rooms, with windows in more than one wall will improve the uniformity of daylighting, reducing glare and providing potential for cross ventilation (CIBSE, 1999). Different window dimensions provide different distributions of daylight (Fig. 3.13) One of the most efficient shading devices in terms of improving daylight distribution is the light shelf, which uses the principle of reflection of light from surfaces. The shelf helps reduce illumination close to the windows while still maintaining acceptable daylight levels to the interior (Fig. 3.14).

The choice of dark or light colouring for the external part of the shading device would have little effect in terms of thermal gain, as most of the absorbed radiation is dissipated back to the atmosphere by convection. Even through a white surface reflects more radiation inward, the net gain in interior temperature is little different, due in part to the second reflection when passing through the glazing (Givoni, 1994). With regard to daylighting however, light, bright coloured light shelves provide much more solar reflection than dark coloured ones.

3.4 Materials The thermal performance of the walls of the building envelope can be improved by utilising a multilayer construction with an air gap. A study by Szokolay (2000) suggested that, given certain preconditions (good solar protection and night ventilation), the combination of high thermal mass materials and an air cavity wall result in lower day time temperatures than with a wall constructed of lightweight materials (Fig 3.15).

Koch-Nielsen (2002) also suggested that whenever a cavity is incorporated as part of a composite building element, the element with the greatest mass (i.e. with high thermal storing properties) should be located on the inner side of the cavity, and the outer side should be of lightweight construction and preferably with high insulation properties. This will allow the amount of heat transfer through the element to be reduced before it reaches the layer that has heat storage properties, which in turn will aid in the reduction of internal heat gains.

Thermal mass can enhance the benefit of natural ventilation where during daytime it can act as a heat sink, absorbing the undesirable heat gain during daytime and dissipating it during the night by convention. The most effective type of thermal mass is the one which has the maximum possible surface area (Fig. 3.16)

31

Chapter 3 – Theoretical background

Figure 3.13 Daylight studies (Source: CIBSE ,1999)

Figure 3.14 The daylight factor profile of a side-lit room (Source: Baker and Steemers, 2002

Figure 3.15 Operation of a heavyweight house (Source: Szokolay, 2000)

Figure 3.16 Cobogo - opaque envelop using high thermal mass materials (Source: Yannas, 2015)

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

3.5 Balconies With good shading and ventilation these spaces can provide a thermal buffer zone to help reduce heat gain to the adjacent living space (Oliveti et al, 2005).

Balconies, functioning as buffer zones, can protect from rain, solar radiation, and reduce noise and dust from the outside. They can also enhance privacy between adjacent spaces in the urban environment (Tsichritzis, 2014). Balconies can also house shrubs in pots and other planting that can provide shade and other benefits outlined in section 1.1 Inset balconies (Fig 3.17) can provide both overhead shading to the apartment below and lateral shading to the subject apartment: offset balconies (Fig. 3.18) shade only the space below. Inset balconies have other advantages: they do not require any cantilevered support, they simplify compliance with setback regulations and suffer less from unwanted exposure to solar radiation compared to offset balconies (Neufert, 2002).

If the floor of the balcony is finished in reflective materials or light colours, the resulting reflections can increase interior daylight levels (assuming the construction of the front of the balcony allows light to pass through, e.g. glass or open railings).

Figure 3.17 Incorporated/Inset balconies (Source: Neufert, 2002)

33

Figure 3.18 Offset Balconies (Source: Neufert, 2002)

Chapter 3 – Theoretical background

3.6 Conclusions It is crucial to appreciate that thermal comfort is subjective, and that users need the sense of control of being able to adjust their environmental conditions to suit their personal preferences. At the same time, because of the many factors that influence thermal comfort, it may well be possible to achieve a satisfactory environment by combining optimised levels of air movement and relative humidity even when temperature is towards the top of the nominal comfort zone.

Air speed and relative humidity are major factors influencing thermal comfort, and both are strongly influenced by ventilation. Ventilation is therefore a key issue, but reducing initial heat gain through solar controls will reduce the thermal problems that ventilation needs to address. Solar controls in turn need to address both direct and diffuse solar radiation.

Building form has a significant impact on airflow patterns around a building, but detailed analysis of these effects falls outside the scope of this paper.

The specification, design and positioning of windows, and introduction of wing wall features, can all improve ventilation. But cross ventilation will deliver better results more simply. Cross ventilation by definition implies windows in different walls, which delivers the additional benefit of much improved levels of daylight compared to apartments with single aspect. Taking all these factors together, designing buildings for cross ventilation has to be the preferred option wherever possible.

Stack ventilation can be effective in providing cross ventilation but may not be practical in high-rise residential buildings.

Green walls can deliver worthwhile benefits although they are not without their problems.

Evaporative cooling has limited potential in the context of Bangkok, but can viably be considered in certain areas.

The thermal performance of walls can be improved by utilising a multi-layer construction with an air gap, and high thermal mass materials can absorb heat gain during the day and dissipate it at night.

However, both these approaches have cost implications and should be secondary compared to implementing effective external solar controls/shading that minimise the heat gain in the first place.

Balconies need to be considered not as independent design elements but as integrated part of an overall design strategy encompassing solar shading, daylighting and ventilation. The conventional perceptions of balconies may be limiting their functionality by perpetuating preconceived ideas of their forms.

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

35

Chapter 4 - Precedents

CHAPTER 4

Precedents

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

4.1 Vernacular architecture The vernacular architecture of Bangkok is a rich source of practical and time-proven ways in which the inhabitants learnt to deal with the hot and humid climate, before they had recourse to modern cooling and ventilating technologies. Figure 4.1 summarises the key features of traditional houses that are adaptive to the climate.

4.1.1

Open layout linked by walkways and orientation

The vernacular Thai house often comprises groups of small buildings linked with walkways, with a courtyard in the middle. Constructing in separate modules like this enables each room to have crossventilation. The building for sleeping has its long faรงade facing north and south. This orientation encourages natural ventilation and the long faรงade catches the prevailing winds that mainly come from the south and north (Fig. 4.2). The kitchen is separated from the main living area, so smoke, smell and heat from cooking do not affect the living spaces.

There are generally no internal partitions within the buildings and therefore no obstructions to air flow through the interior.

4.1.2

Verandahs/buffer zones

There are covered walkways separating the indoor and outdoor spaces, which act as transitional spaces that can control and enhance airflow into the interiors (Fig. 4.1). Covered verandahs also act as thermal buffers between inside and outside spaces (Sirichanchuen, 2015) Verandahs in traditional buildings have many functions in common with balconies in contemporary high-rise buildings.

4.1.3

Air-permeable walls

Air permeable walls are often seen in the kitchens of traditional buildings (Fig. 4.1), and are occasionally found in other areas. The better ventilation they allow is beneficial for removing the smoke and smells of cooking, as well as providing enhanced cooling. There are two common types of traditional air-permeable walls, fixed and adjustable. The most common, simple and nonadjustable permeable walls are generally restricted to kitchen areas only as they offer reduced privacy and can be problematic in living areas during periods of high winds or heavy rain.

4.1.4

Window openings

Windows start from around 40 centimetres above the floor (Fig 4.3). In traditional buildings people are commonly sitting on the floor, so this starting height provides some privacy combined with clear views while sitting. It also allows wind flow at a level suited to people sitting on the floor.

4.1.5

Materials

Traditional building materials are timber and clay, the latter made into roof tiles. (Antarikananda P.,et al, 2006). Bamboo is also used. The low thermal mass of these materials ensures that the building envelope does not store the heat during the day and enables interior temperatures to drop rapidly at night in line with cooler outdoor temperatures.

4.1.6

Roofs

Roofs are high pitched, with a large overhang on all sides to protect the external walls and interior from direct solar radiation and rain (Fig. 4.1). The high pitch, with no internal ceiling or division, allows warm air to rise and exit through gaps between the tiles.

4.1.7

Raised floors

Traditional buildings have the living areas on floors raised on columns (Fig. 4.1). This design reduces risk from flooding, creates a shaded storage and daytime living space and provides underfloor ventilation. The space under the elevated floor is traditionally used as a living space during the day as it is cooler than the upper floor. The principle of reducing flood risk by raising the structure on columns is just as valid in modern Bangkok, with its frequent flooding, as it was in the past.

37

Chapter 4 - Precedents

Figure 4.1 Summary of the keys feature in vernacular Thai house.(After: Cholasuek; 2010, Sirichanchuen, 2015)

Figure 4.2 Optimal orientation and distance between buildings (Source: Cholasuek, 2010)

Figure 4.3 Window design of Thai vernacular architecture (Source Cholasuek, 2009)

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

4.2 Contemporary buildings This section will explore examples of buildings in both Bangkok and similar climates that have successfully incorporated some of the strategies explored under “theoretical background” 4.2.1

TTDI building (Kuala Lumpur - Malaysia)

The apartments are in two blocks linked with walkway. This configuration creates more external wall, more opportunities for windows and more potential for cross ventilation. The walkways incorporate voids either side of the walkways (Fig 4.4 b) in the central section of the building, and at each end of the building (Fig 4.4 c), to allow upward wind flow and a stack effect.

The overhanging sections of floor function as shading devices against direct solar radiation (Fig. 4.4 a). Under these are light shelves that serve a dual purpose. They reflect daylight into the living space, and as they extend outwards further than the overhanging floor above, at a lower level, they create a shading effect equivalent to a much deeper overhanging floor.

Tantipat (2011) carried out fieldwork on a unit located on the 13 th floor at the North-West corner of the TTI building. Tantipat reports that when windows and the front door (with metal grille) are opened, cross-ventilation provides a significant cooling effect, enabling the occupant to feel comfortable during the day, albeit sometimes with further cooling assistance from an electric ceiling fan.

Despite the shading arrangements, Tantipat reports that there is still a problem with glare during the afternoon, resulting in the need for blinds on most of windows to enable the (elderly) occupant to watch television clearly.

4.2.2

The Met (Bangkok)

The Met is a high density building designed to provide naturally ventilated accommodation. There are similarities in its core concept to the TTDI building, in that it comprises linked elements rather than a monolithic structure (Fig 4.5). In the case of the Met tower it is composed of three staggered blocks that are joined with sky terraces every five stories. This arrangement provides all apartments with access to light and air on all four sides, optimising the potential for cross ventilation. Ali (2013) interviewed the occupants of seven rooms between floors 29 – 62. Five out of the seven reported satisfaction with the performance of the ventilation at most times of day, and that they felt comfortable without needing to use air-conditioning.

4.2.3

No.1 Moulmein Rise (Singapore)

The climate of Singapore is hot and humid year round, but compared to Bangkok it experiences even higher rainfall No.1 Moulmein Rise in Singapore features monsoon windows (Fig. 4.6), inspired by a traditional design used in the Dayak longhouses of Borneo. The monsoon window incorporates a horizontal opening within a projecting ledge, which permits ventilation without ingress of rain 4.2.4

Happy land Townhouse and Allzone Headquarters (Bangkok)

Happy land Townhouse features an offset façade of vertical timber columns supporting a woven mesh of fibre derived from banana plants (Fig. 4.7). The mesh provides shade, enhances privacy and provides a matrix to support a green wall.

The headquarters of Allzone also features an offset facade, but in this case comprising a variety of different patterns of concrete blocks held within a steel framework, providing shade, privacy and security (Fig. 4.8). An additional element of the Allzone façade is wire mesh floors that have been installed into the space between the façade and the building (Fig 4.9), creating transitional spaces on each floor that function as balconies. The concrete blocks were originally finished a range of colours, but the architect owners found that this affected the colour of the interior light to a degree that they found unacceptable, so the blocks were changed to shades of grey (Fig 4.8).

Tedkajohn (2013) carried out fieldwork on both buildings. The studies reported that the permeable facades were both effective in reducing levels of solar radiation while maintaining good ventilation.

The studies also suggested that orientation has little effect on the internal temperature if the rooms are well protected from solar radiation. The Happyland Townhouse was found to have higher39

Chapter 4 - Precedents

Figure 4.4 TTDI building (Source: Tantipat, 2011)

Figure 4.5 The Met, 30th floot plan (Source: Ali, 2013)

Figure 4.6 No.1 Moulmein Rise - section detail of monsoon window (Source: CTBUH, 2009) 40

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

relative humidity, which was considered to result from both the green wall, and the limited potential of the building design for cross ventilation.

4.3 Conclusions The vernacular concept of separate buildings linked by walkways and with by shading from overhanging roofs has echoes in contemporary high rise designs that comprise multiple modules with air gaps and voids between, and incorporating a range of shading solutions.

Verandahs in traditional buildings have many functions that could be replicated with balconies in contemporary high-rise buildings, if some of the common limitations with balconies can be addressed. The wire-floored quasi-balconies in the Allzone building, with concrete block frontage, raise ideas of balconies with perforated or permeable floors, and balconies fronted in ways other than open space or glass.

Similarly, traditional permeable walls of timber and bamboo can be seen translated into modern equivalents using concrete, natural fibre and other materials. While contemporary equivalents have proved to be a practical element to protect both direct and diffuse solar radiation at the same time allowing natural ventilation and daylighting. they have also revealed issues with higher tech materials, such as the unexpected colour distortions caused by coloured concrete shading elements.

The traditional construction materials of timber, clay and bamboo draw attention the benefits of low thermal mass construction in a hot climate.

The high-pitched roofs of traditional building, and venting of risen hot air though the tiles, suggest that thought might be given both to maximising ceiling heights and considering ways in which the hot air that rises to the ceiling could effectively be vented out rather than simply recirculated by fans or artificially cooled.

The traditional principle of reducing flood risk by raising a structure on columns and making flexible use of the open space so created has continuing relevance in high rise buildings, despite their very different form factors.

The location of the windows in tradition Thai house and monsoon window of No.1 Moulmein rise highlight the careful attention for design opening to deal with different purpose.

The combination of overhanging floor with light shelf under, used in the TTDI building, is an elegant solution. In the context of Bangkok, this concept would enable effective shading while minimising the outwards projection from the building and thus its impact on the building’s regulatory footprint.

All elements of a building are important: design, construction and materials, and there are many ways of achieving good results. What this review highlights is that there are two issues, perhaps above all others, that justify the most careful thought in the context of high-rise buildings in Bangkok: shading and cross ventilation.

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Figure 4.7 Happy land Townhouse front faรงade and floor plan (Source: Tedkajohn, 2013)

Figure 4.8 Allzone Headquarters front faรงade and floor plan (Source: Tedkajohn, 2013)

Figure 4.9 Wire mesh floors located between the faรงade and the building (Source: Tedkajohn, 2013)

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Chapter 5 - Fieldwork

CHAPTER 5

Fieldwork

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The objectives of the fieldwork are twofold. Firstly, to investigate the performance of two typical apartments in high-rise buildings in Bangkok by spot measurements and data logger. Secondly, to gain an understanding of how the occupants use the space, and of their subjective experiences of what makes them feel comfortable and why, through interviews and records of their activities throughout the day.

The studies compare two one-bedroom apartments, both facing north, of different sizes, aspects and heights. The studies took place in the first two weeks of July, which is a wet and warm period with prevailing winds mainly from the south.

5.1 Interviews 5.1.1

The Rhythm building (Fig 5.1) - Medium size/middle budget apartment (Apartment M)

The apartment is located on the 8th floor, with 2 external walls. The walls are lightweight concrete block with plaster finish and the floor is wood laminate in all areas except the bathroom and balcony, which have ceramic tile floors.

Occupants: 2 adults.

From interview (Apartment M) The occupants indicate satisfaction with the overall character of the apartment and its dimensions.

They have little problem with direct solar radiation, but more with reflected solar radiation from the surrounding buildings (as the apartment is at relatively low level) (Fig. 5.2). Ventilation is ineffective during summer so the windows are kept closed for most of the time and the occupants rely on air conditioning. In winter natural ventilation can maintain acceptable comfort levels for some of the time. The occupants enjoy sitting on their balcony when the outdoor conditions are suitable. They do not experience any problems with noise.

5.1.2

The U-Delight (Fig. 5.3) - Small/low budget apartment (Apartment S)

The apartment is located on the 24th floor with 1 external wall. The walls are precast concrete with a painted finish and the floor is wood laminate in the bedroom and living room. The kitchen, bathroom and balcony have ceramic tile floors.

Occupants: 2 adults, 1 child.

From interview (Apartment S) The occupants like the layout of the apartment and very much enjoy the high location with its good views and minimal dust pollution, even with a furniture factory nearby. From time to time they like to go out on the balcony to enjoy the view. The occupants report dissatisfaction with the design of the glazing between the balcony and the interior, as if the window is open when it rains, rain is often blown into the apartment. As the result, the occupants have to use a curtain to help control the wind (Fig. 5.2). When the mother of the family is in the apartment on her own she reports that she is comfortable with a combination of natural ventilation from opening the windows, supplemented by an electric fan, even during the summer period and rarely uses the air conditioning. However, whenever her children or husband are home they automatically turn on the air conditioning, at all times of year. The family also complain of inadequate soundproofing, because they can hear their neighbours talking and their neighbours’ daughter playing the piano.

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Figure 5.1 The Rhythm building - Apartment M (Source: http://www.apthai.com) Figure 5.2 View from the living room (Apartment M)

Figure 5.3 The U-delight building - Apartment S (Source: http://www.grandu.co.th) Figure 5.4 Curtain on the balcony (Apartment S)

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5.2 Spot measurements The data was recorded in two sessions. In the first session the air conditioning was turned off. In the second session the air conditioning was turned on at a setting of 25 C. All windows were closed in both sessions as this is the typical habit of both occupants of these rooms.

The data recorded included temperature, wind flow, humidity, surface temperature and daylighting on a sample day. i.

In apartment S the kitchen is separated from the bedroom and living room by a glazed partition. The kitchen has a ceramic floor and exposed concrete walls, which are both high thermal mass materials, whereas the bedroom and living room have timber floors with much of the wall surface covered by wooden furniture. The temperature in the kitchen is consistently almost 1.5K higher than in the bedroom and (linked) living room (Fig. 5.5). The higher temperatures in the kitchen seem likely to be due to the heat output of the refrigerator. This factor, together with the additional heat gain in the kitchen from cooking (and the related smells) suggests that separating kitchen and living areas is highly desirable, and that the effect of using low thermal mass materials in the kitchen should be investigated.

ii.

As expected from the climate studies in section 2.3.4 during the summer period the prevailing wind is from the south. Both apartments studied only have windows facing north. As the result, even with all windows open, the wind velocity barely rises above 0 m/s even in the areas close to the windows on both on the 8th and 24th floor. Opening the front door can create some cross ventilation, but this is minimal: a wind velocity of just 0.5 m/s (See appendix B). These observations confirm the need for building designs to ensure better ventilation, especially in buildings which are not orientated to face the prevailing wind direction.

iii.

Measurements were taken in apartment S on a precast concrete wall dividing the apartment from the adjacent dwelling. It was noted that the surface temperature dropped by up to 1K when the neighbours switched on their air conditioning (Fig 5.6). This identified a need for an improved specification for the dividing wall to prevent temperature transfer between adjacent units.

iv.

The same precast concrete wall mentioned above was partially painted and partially covered with fabric over an unidentified foam material (intended to be sound absorbing). After the air conditioning had been switched on for 10 minutes the surface temperature of the painted concrete reduced from 30 to 27.2 (-3K). On an adjacent section of fabric-covered wall the surface temperature reduced from 31 to 23 (-7k), a reduction of 4k more than on the painted surface. Over the same period the surface temperature of the timber furniture in the room reduced from 30 to 24 (-6K) (Fig. 5.7). These observations were an interesting practical confirmation of the way in which materials of lower thermal mass follow changes in air temperature much faster than materials of higher thermal mass.

v.

When the electric fan was switched on the relative humidity in the surrounding area decreased by 5%-10%, confirming the benefits of mechanical ventilation when natural ventilation is not available (see appendix B).

vi.

The kitchen in Apartment M is located at the rear of the apartment and has a daylight level of 45-48 lux (Fig. 5.8). The occupants report that they have to switch on the electric lights when they want to cook. By comparison, in Apartment S the kitchen is adjacent to a balcony and the lux level at counter height ranges between 180-900 lux: when the occupants want to cook they simply open a curtain. In both cases the outdoor light levels are similar, at 70,000-80,000 lux.

vii.

The Rhythm building has an enclosed, glazed lobby area, as is common in upmarket residential buildings. The U-delight building has an open space that functions both as a lobby and playground area. There was minimal air movement inside the lobby in the Rhythm building, but a nearly consistent 1-2 m/s wind velocity within the ground floor of the U-delight building, during the times visited (Fig. 5.9).

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Figure 5.5. (Apartment S) temperature

Figure 5.7. (Apartment S) Surface temperature

Figure 5.6 (Apartment S) surface temperature

Figure 5.8. (Apartment S&M) Spot measurements – Daylight

Figure 5.9 Lobby area on the ground of Rhythm building (left) and U-Delight building (right)

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5.3 Data logger The data loggers were placed in Apartment M between 3-6 July and Apartment S between 8-11 July.

Occupants in both apartments agreed to record their activities during these periods. Four data loggers were used to record temperature, one in each of the following locations: balcony, bedroom, living room and kitchen which is then compare with outdoor temperature recorded at the Don Muang airport (from wunderground.com) (Fig 5.10-5.11) i.

In both Apartment M and Apartment S the outdoor temperatures during the night on the balconies are consistently higher than the temperatures recorded at the nearby airport (10km away). This may indicate a heat-island effect in the densely built-up areas where the buildings are located. Additionally, or alternatively, the floors of the balconies may have sufficient thermal mass to be releasing heat overnight. Apartment M, which is located on the 8th floor, records higher balcony temperatures both day and night than those recorded at the airport weather station. Day time can be higher by almost 2k and night time higher by 4k. Apartment S on the 24th floor shows a similar day time temperature to the airport but night time temperatures are higher by 3k. This suggests that the higher the floor the less it is affected by the urban heat island phenomenon.

ii.

The Apartment S unit shows a decouple in the temperature between the kitchen and the other areas. The kitchen cycled between 31-32 C during all four days in a consistent rhythm (Fig. 5.11). This seems likely to have been caused by the refrigerator cycling on and off. The data logger measurements confirmed the findings of the spot measurements and the need for separating the kitchen area from the living space.

iii.

In Apartment S (Fig. 5.11), when there is one occupant during the day, the temperature in the combined bedroom/living room remains around 30-31 0C (the living room space is very slightly cooler due to its location at the rear of the apartment where it receives little solar radiation).

The observed temperature falls within the comfort band, which is in line with the interview with the resident mother who states that during the day she is comfortable without using the airconditioning. She reported that when her children and husband are home they turn on the air conditioning. This may be simply due to habit or habituation to air conditioned environments, or may be influenced by the additional heat gain and higher humidity from more bodies in an environment with poor opportunities for ventilation.

iv.

In Apartment S it takes 1-2 hours for the temperature to drop to 24 0C after the air conditioning is switched on. In Apartment M the same reduction in temperature takes 3-4 hours. This is due to a combination of factors. Compared to Apartment M, Apartment S has a smaller area of external walls, smaller volume and some walls covered in foam and fabric. As a result, it takes only 1-2 hours for the temperature in Apartment S to drop to 24 0C from the time the air conditioning is switched on, whereas Apartment M takes 3-4 hours to achieve the same reduction. This indicates a practical benefit of low thermal mass materials in areas occupied at night, such as bedrooms, when the outdoor temperature falls within the comfort band.

v.

During periods of rain the outdoor temperature dropped by 7-8k, indicating a good theoretical opportunity to couple the rooms to the outside environment by ventilation. In practice the occupants of both apartments kept the windows closed to avoid excessive wind and ingress of water,

vi.

The occupants in apartment M turned on their air conditioning even when the overall indoor temperature was 30 0C, which is still within the comfort band (Fig. 5.10). While one of the occupants frequently used a laptop, which would create a very small increase in temperature, the most likely reason for the use of air-conditioning seems to be habituation to air-conditioned environments.

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Figure 5.10 (Apartment M) Data loggers (3-6 July)

Figure 5.11 (Apartment S) Data loggers (8-11 July) 50

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

5.4 Conclusions The fieldwork confirms that ventilation in the apartments studied is inadequate. Ventilation, and crossventilation in particular, need to be given far greater importance within the initial design process. in relation to the control of both temperature and humidity.

Balcony and glazing design needs both to encourage ventilation and to prevent the ingress of water during rainfall. The design of balconies should also ensure that they are effectively shaded and of low thermal mass to avoid the build-up and storage of heat within their structures.

The construction of dividing walls between apartments needs to combine adequate soundproofing qualities and heat insulation but with high thermal mass.

Kitchens should be separated from living areas, and particular attention paid to their ventilation given the heat gain from the appliances used and the cooking smells generated.

Kitchens should be located such that they receive sufficient daylight to carry out common tasks without the need for supplementary lighting.

The effectiveness of portable electric fans observed during the fieldwork suggests that ceiling fans should be installed as part of the standard specification for apartments.

Open ground floors under raised buildings can fulfil a range of useful functions as transitional spaces.

There appears to be evidence that air conditioning is sometimes used out of habit rather than need, and perhaps because occupants personal thermal comfort zones have been distorted by spending a lot of time in air conditioned environments elsewhere. Ways should be explored to encourage apartment occupants to avoid using air conditioning, primarily by improving the free-running thermal environment, but perhaps also by live display of energy use and related costs.

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Chapter 6 – Analytic work

CHAPTER 6

Analytic work

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

The analytic work draws on the insights outlined in previous chapters to create appropriate simulations to guide key design choices. These analysis in turn will inform the development of guidelines for the design of high rise residential buildings in a hot and humid environment.

OpenStudio and Energy+ software was used for thermal simulations, DIVA for daylighting, Autodesk Flow Design for wind flow and Grasshopper for solar analysis.

The simulations to be explored are as follows: 1. Indoor analysis 2. Balcony analysis

6.1 Indoor analysis The analyses explore the following parameters: Shading devices, Building form, Natural ventilation, Materials and Occupancy.

The starting point of the analyses is the establishment of a base case, which is outlined below. Then, as the first four parameters listed above are tested the specifications of the base case will be progressively modified, building towards an optimised model. This optimised model will then be tested both with two occupants present only during the evening and overnight (as in the base case) and with a more challenging scenario of two occupants present all day and four occupants (i.e. plus two visitors) over the weekend.

The model has been calibrated with the fieldwork unit of U-delight model (Fig. 6.1) as this model best represents the typical construction and dimensions of a one-bedroom apartment in high-rise residential building in Bangkok. The temperature for the OpenStudio model is higher because it cannot take account of the issues identified relating free cooling load from the neighbouring apartment (See section 5.2 {iii}).

Some simplifications were also applied to reduce the complexity of the model to enable the software to provide clearer results in relation to the proposed interventions (summarised in Table 6.1).

Zoning is not included, so the internal heat gain is the average of all the room types. Both literature review and precedents lead to the conclusion that the kitchen area should be designed so that its thermal performance should not affect the living area, therefore all the internal heat gain from the kitchen will be excluded from the simulation.

For the purposes of the simulation the balcony has also been removed. A balcony serves as a buffer zone and influences the adjacent space. Simplifying the model by removing the balcony will avoid introducing this variable.

The simulation uses the 20th Floor of a 40 storey building (Fig 6.2) to represent a unit with no overshadowing from surrounding low-rise buildings (in Bangkok the majority of buildings are 8 floors or less ), so the studies can exclude heat island effects (raised temperatures), reflection from nearby structures (increased diffuse solar radiation and glare), overshadowing (protection from direct solar radiation at certain times according to orientation) and wind obstruction (increase or decrease in wind velocity ).

In a hot climate the higher the window to wall ratio (WWR) the greater the risk of excessive heat gain from solar radiation. However, as discussed in section 3.2.1, large glazing areas are considered desirable to maximise views. This dissertation will therefore not study the influence of glazing size, but will seek to deal with the reality of preferred glazing ratios in Bangkok by using a WWR of 65%.

Windows are assumed to be closed to correspond with what was found during fieldwork.

The base case assumes a realistic scenario where the occupants are at work during the day and only present in the apartment between 18:00-08:00. The initial focus is therefore on optimising thermal comfort for the occupants on their return from work and overnight.

The simulations were conducted in a typical week of March, which is the hottest month of the year but to give the most relevant results the very hottest week was not used.

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Figure 6.1 Calibrated simulations

Figure 6.2 Base case (simplified version) Table 6.1 Base case parameters summary (simplified version)

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

6.1.1 Shading devices As discussed in Section 3.2, shading devices were selected as the first priority as solar radiation is both the primary source of thermal discomfort and an environmental factor that can be mitigated in virtually all site scenarios. i.

Fixed shading device

The simulation will first test a fixed horizontal shading device as it has been identified to be of primary importance for all orientations (see section 3.2.1 {i}). Account will be taken of the setback regulations in Bangkok, explained in section 2.2. A consequence of these regulations is that most high rise developments exclude shading devices from their designs as including them effectively reduces the permitted floor area. The maximum dimension of a shading device that is allowed before it becomes an element taken into account by the regulations (regulation 55 section 43) is 0.5m. This dimension will therefore be used to reflect the commercial realities of building in Bangkok.

The simulations test two different designs of shading device (Fig. 6.3): 1. Fixed horizontal shading device 2. Fixed Horizontal + Vertical shading device The results will show the operative temperature and compare how the average daily transmitted solar radiation through glazing for both direct and diffuse radiation changes, in the four orientations north, south, east and west.

Figure 6.3 0.5m fixed shading devices - Left Horizontal, right Horizontal and Vertical combined

a) Results for fixed horizontal shading device As expected, with a fixed horizontal shading device used on a south facing facade there is a large reduction of around 80% in direct solar radiation and a reduction in temperature of almost 1.4k during peak hours (Fig 6.4).

On a north facing faรงade the fixed shading device has very little effect on temperature (less than 0.1k) (Fig. 6.6). However, at this time of the year the sun path tracks entirely to the south (Fig. 6.8): we can expect that the results for north orientation in May-July would be similar to the results for south orientation during the test period.

Both east and west facing facades show an expected much smaller reduction of around 25% in direct solar radiation. The shadow mask diagrams (Fig 6.9 {left}) show that the shading can provide protection only from late morning (for east orientation) and early afternoon (for west orientation), but this still provides a temperature reduction around 0.9 K during peak hours which is still worthwhile (Fig. 6.5 & 6.7).

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In all orientations the diffuse solar radiation remains very high, almost 2-2.5 kWh per day (Fig.6.4-6.7).

This is a reduction from the base case of only 10-20%. This shows that the overhang will only be effective in relation to direct radiation and that diffuse radiation needs to be addressed in another way. b) Results for fixed horizontal + vertical shading device A vertical shading device should in principle protect against early morning and late afternoon sun (see section 3.2.1). This variation was analysed using a shadow mask tool (Fig 6.9 {right}). The results showed that the north orientation was protected during the period April to August when there is exposure to direct solar radiation. For the south orientation the protection during April to August is irrelevant, as it is not exposed to direct solar radiation during this period. South orientation is exposed to direct solar radiation from September to March: during this period the vertical shading device provides shading during early morning and late afternoon during February to March and September to October.

East and west orientations shows little benefit overall from vertical shading devices and almost none during the summer period, so such devices cannot be justified for these orientations. Note that is not shown on the shadow mask diagram for East and West due to the “point of interested� being located in the middle of the window).

The graph of the simulation over the course of the year (Fig. 6.10) shows that adding vertical shading to east and west orientations reduces direct solar radiation by approximately 5%, to south orientation by 13% and north orientation by 27%.

It may be concluded that a fixed horizontal shading device of 0.5 m depth is worthwhile for buildings of all orientations. Vertical shading devices either side of the very wide glazed areas can be recommended for north and south orientations only. c) Additional observations on depth of horizontal shading In east and west orientations, to address solar radiation when the angle of the sun is low, potential solutions include inclined overhangs and vertical shading either side of glazing. This latter solution could also be applied to south and north orientations to allow a reduction in the depth of horizontal shading. However, inclined overhangs and vertical shading can both obstruct views to a degree that may be unacceptable to occupants. Conversely, a positive supplementary benefit of overhangs for all orientations includes protection from rain.

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Figure 6.4 Results for fixed horizontal shading device (south orientation)

Figure 6.5 Results for fixed horizontal shading device (east orientation) 59

Chapter 6 – Analytic work

Figure 6.6 Results for fixed horizontal shading device (north orientation)

Figure 6.7 Results for fixed horizontal shading device (west orientation) 60

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

Figure 6.8 Sun path diagram for Bangkok

Figure 6.9 Shadow mask diagrams for fixed horizontal shading device (left), horizontal and vertical combined (right)

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Figure 6.10. Comparison between each orientation of yearly transmitted solar radiation results for fixed horizontal and horizontal + vertical shading device

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Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

ii.

Adaptive shading device

An external, perforated three-dimensional screen of a defined minimum depth can provide an effective solution for blocking both direct and diffuse solar radiation, as it can block a wide range of different angles of solar radiation without significantly impacting on ventilation or daylighting (see section 4.2.4 for details).

The disadvantage of such shading devices is that they significantly obstruct the view when in use. For residential applications such devices must be adaptive (moveable) in all areas other than service areas or toilets, where the outlook is not relevant, or in specific circumstances where a view is not desirable (e.g. outlook onto a solid wall or unattractive structure).

In this section, all simulations of adaptive shading devices will also incorporate a fixed horizontal shading device, as it has been established earlier that this is desirable design element for all orientations.

The simulations test the thermal and daylighting performance of three different designs of shading device (Fig. 6.11): 1. Vertical louvre.

2. Horizontal louvre.

3. Combined vertical + horizontal louvre.

All louvres are specified as 10cm deep with a 10 cm spacing between slats.

Figure 6.11.Types of adaptive shading devices

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a) Adaptive shading device – thermal Applying louvres on the north orientation decreases diffuse solar radiation by 29% - 47% (Fig. 6.14), but there is minimal reduction in temperature. This suggests that louvres are poorly justified on north orientations.

Applying louvres on the south orientation decreases diffuse radiation by 33% with horizontal louvres, 39% with vertical louvres and 50% with combined louvres (Fig. 6.12). There is a reduction in temperature of 0.3-0.4 K for all louvre types. Given these results there would be no benefit in specifying combined louvres, with their greater complexity and greater difficulty of implementation in adaptive form. Either vertical or horizontal louvres would deliver similar benefits: the choice would be guided by the aesthetic and practical considerations of any given context.

Applying louvres to the east and west orientations showed that horizontal and combined louvres delivered the best performance, reducing both diffuse and direct radiation by up to 70% for east orientation (Fig. 6.13) and 61% for west orientation (Fig. 6.15) and reducing temperature by almost 2 K on the hottest day (Fig. 6.13 & 6.15). As there was little difference between the thermal performance of horizontal and combined louvres the recommendation would be for horizontal louvres as they are simpler, more flexible in application and less costly.

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Figure 6.12. Results for adaptive shading devices (South orientation)

Figure 6.13 Results for adaptive shading devices (East orientation) 65

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Figure 6.14 Results for adaptive shading devices (North orientation)

Figure 6.15. Results for adaptive shading devices (West orientation) 66

Design guidelines for or towards free-running high-rise housing in the hot and humid urban environment of Bangkok

b) Adaptive shading device – daylighting A shading device that provides supplementary protection from solar radiation while maintaining daylight levels is the light shelf (discussed in section 3.3), which blocks solar radiation while reflecting light into the interior. The louvre designs tested utilise the same principles. Similarly, the colour and thermal conductivity of a light shelf has little effect on its performance, so long as the gap between the device and the building envelope is large enough for the absorbed radiation on the shading to be dissipated by convection to the outdoor, and small enough for light to be reflected into the interior. This is equally true of louvre designs. The colour of the louvres for the daylighting analysis will therefore be set to white to maximise reflected light: if light levels are too high they can easily be attenuated by internal blinds.

For the simulations the receiver (nodes) in the DIVA software are located at 850 mm above the ground, to represent the average working level.

The typical sky conditions in Bangkok are overcast. The Daylight Factor (DF) which is used for the simulation is therefore representative of overcast sky conditions.

The typical finishes selected represent single glazing, walls painted smoke-white, white ceilings, wood flooring and white shading device. The resulting numbers for calculation purposes summarised in table 6.2 -

Results

Combined louvres deliver the best reduction in glare, but horizontal louvres provide the best results for daylighting distribution (for all orientations) (Fig. 6.16). Vertical louvres deliver the poorest outcomes for both glare and daylighting distributions.

Both fieldwork and precedents highlight a problem with glare in living areas. At the same time, the area that requires the highest level of daylight is the kitchen: around 300-500 lux (CIBSE, 2006) and daylight factor of 2%. This suggests that the kitchen should be located adjacent to a large area of glazing, which would also simplify the venting of smoke and odours. To minimise glare, living areas should be located further from glazing, so long as care was taken to ensure adequate levels of daylight. In practice, however, living areas need to have the benefit of views, so the compromise would be living areas of sufficient depth to enable the occupants to avoid the areas of high glare adjacent to the glazing. The simulations show that even with a highly protective shading device there still potential for glare around 1-2 meters from the glazing, so this needs to borne in mind when planning internal layouts.

One way to reduce glare, provide better daylight distribution and create opportunities for crossventilation is to have windows on more than one wall (see section 3.3). The next section will compare the performance of a selection of building forms that provide apartments with more than one external wall.

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Table 6.2 Specification summary for daylight simulations

Figure 6.16 Daylight analysis for adaptive shading devices

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From the test results outlined in the preceding texts the optimised configuration model will incorporate fixed horizontal shading and horizontal and vertical combined louvres. This should provide the test units with the highest level of protection from both direct and diffuse solar radiation.

6.1.2 Building form The climate analysis led to the conclusion that south and north orientations were preferable to minimise solar gain and maximise potential for natural ventilation (see section 2.3.2 & 2.3.4).

Throughout the year the south orientation will received more solar radiation – thus presenting greater challenges – so the following analyses of building form will focus on south orientations only.

It is very evident from simple observation that the vast majority of high rise residential buildings in Bangkok are of monolithic design: rectangular prisms of varying proportions. Further, they almost invariably incorporate apartments on two opposite sides of the building, with the consequence that most apartments have only one external wall.

The climate analysis indicates that in Bangkok it is desirable to have building interiors coupled with the outdoor temperature, as for most the time the outdoor temperature is within the comfort band, especially during the night and during periods of rain. The most efficient way to achieve this coupling is to provide cross-ventilation. This in turn requires openings on more than one façade, i.e. buildings of a form such that apartments have more than one external wall.

The typical construction materials used usually have low insulation properties, therefore increased external wall area and thus more exposure to the outdoor atmosphere will also help dissipate excess internal heat gain by convection.

With influence from the TTDI building and The Met (both discussed in section 4.2.1-4.2.2), three alternative forms have been selected, providing the test apartment unit with two, three, and four external walls respectively. (Fig. 6.17) The fieldwork shows that increased external wall area would result in more potential heat gain from radiation through the envelope. To minimise this effect the voids between building elements have been set at 2.5m, wide enough to allow effective wind flow and to incorporate walkways (which are regulated to a minimum 1.5m {regulation 55 section 21}), but narrow enough so that adjacent buildings provide shade to each other.

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Results

As expected, the results show that the interior temperatures are more closely coupled with (cooler) outdoor temperatures, especially during the night (due to the low insulating properties of the walls) (Fig 6.18).

Daytime temperatures drop by 1-2 K for all variants (2, 3 and 4 external walls). Night time temperatures drop by 1-1.5 K for 2 walls, 2.5-3 K for 3 walls and 3-3.5 K for 4 walls (the drop in night time temperature naturally has an impact on day time temperatures, as the starting temperature is lower). It needs to be borne in mind that the tests exclude the effect of natural ventilation, and once that is factored in the difference in the reduction of night time temperature between 3 walls and 4 walls is likely to narrow further.

Given the very similar performance of units with 3 and 4 facades there are good reasons for selecting units with 3 facades for the further analyses. Units with 3 facades will be considerably less costly to construct, there will be a smaller reduction in usable floor area, and greater potential for sharing service ducts (water pipes, electricity cables etc.) The optimised model will therefore comprise a unit with 3 facades.

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Figure 6.17 Comparison of various building forms

Figure 6.18 Comparison of various building forms and their effect on internal temperatures

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6.1.3 Natural ventilation Preparatory tests showed that a ventilation rate of 15 ac/h enables room temperature to follow outdoor temperature closely (see Appendix C1). Levels of air change higher than this deliver no meaningful further reductions in interior temperature. i.

Opening size

Once the minimum ac/h to enable the room to couple with the outdoors was defined, simulations were carried out with a selection of combinations of openings (Fig. 6.19) to identify which would deliver a rate of air change rate meeting (or exceeding) the defined rate.

The first test using matching square openings of an area of 1 m2 provided ventilation rates ranging from 5 – 40 ac/h; the level only exceeded 15 ac/h for 39% of the time. Changing the shape of the outlet to a landscape rectangle made no meaningful difference (Fig. 6.20).

When the inlet opening was increased in size by a factor of 3, to 3 m2, the number of hours with ac/h above 15 increased to 47%. But when both inlets and outlets were increased to 3 m 2 the percentage of time with a rate of 15 ac/h or above increased to 75% (Fig. 6.20).

These simulations lead to the conclusion that providing large openings of equal area provides the best results.

Day 11/03 has very low levels of outdoor air movement (Fig. 6.20). In these circumstances thermal comfort could be improved by the use of fans/mechanical ventilation. Increasing the size of openings further would have little impact in the absence of greater outdoor air movement. ii.

Using windows to control ventilation

While users like to be able to exercise control over their environment, if the process is too complex they will not do so. This factor arguably favours the simplest level of adaptability necessary to achieve user satisfaction.

The fieldwork identified that the occupants never open the windows during the day, when they are out, and only sometimes when they are in the apartment, at night (18.00-08.00). Night time temperatures in the test week are always within the comfort band. Simulations were carried out to identify the effect of opening the windows both day and night and just opening during the night.

By leaving the windows open during the day, the temperature when the occupants return (around 18:00) will be 2 – 2.5 K lower than if the windows are left closed (Fig. 6.21). Although the temperature will eventually drop to the same level with windows just opened at night, there will be an initial period of 2-3 hours during which the temperature will be much lower if the windows have been left open during the day.

All-day ventilation performs well during most of the test period. However, there are occasions (e.g. days 09/03 and 11/03) where the dramatic rise in outdoor temperature suggests that the indoor temperature would actually rise more slowly if the windows were closed. This issue will be explored further in subsequent testing (6.1.5 {i}).

The simulations show that leaving windows open all day is the most effective strategy for lowering internal temperatures for occupants who are at work during the day. On occasions when they are at home during the day, such as at weekends, they should close the windows when the external temperature is higher than the internal temperature.

There is a further issue that leaving windows open all day raises concerns over possible water ingress in the event of rain. This highlights the need for consideration of window designs that provide ventilation while preventing water ingress, e.g. monsoon windows (see section 4.2.3) For the optimised model the windows will be open all day with a minimum air change rate of 15 ac/h all day and night.

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Figure 6.19 various configurations of openings

Figure 6.20 Air changes per hour with various configurations of openings

Figure 6.21 The effect of selected patterns of ventilation on internal temperature

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6.1.4 Materials i.

Walls

The base case outlined above at 6.1 specifies lightweight concrete walls. Literature review prompted the exploration of a double layer wall, as it is known that a wall construction combining materials of both low and high thermal mass separated by an air gap can potentially help lower daytime temperatures (see section 3.4).

To explore this option in the target context, the following wall specifications were selected for simulation: -

100 mm lightweight concrete 100 mm heavyweight concrete 200 mm heavyweight concrete 100 mm heavyweight concrete, with an outer layer of a timber panel 25 mm thick, the two separated by a 100 mm air gap (cavity wall).

The results show that 100mm heavy concrete reduces temperature by only 0.1- 0.3 K compared to 100mm lightweight concrete (see Appendix C2). The performance of 200mm heavy concrete and the cavity wall are very similar (see Appendix C2), reduction of 0.8 – 1 K during peak hours. The cavity wall was therefore selected for the optimised model. Although the construction of the cavity wall is more complex, that disadvantage is outweighed by its much lower weight and corresponding reduction in the depth of foundation required, and its lower carbon footprint. Factors that influence the specifications of foundations are especially important in Bangkok, as the city is located on a deltaic plain and piled foundations are required to transfer the load to deeper soil strata.

Simulations were carried out using this cavity wall construction on the two most exposed external facades, then on all three external facades (the remaining walls being 100 mm heavy concrete).

The results showed little difference in performance between using this cavity wall construction on two or three external walls (see Appendix C3), logically due to the more shaded (third) façade being subject to insufficient solar radiation for its construction to have much effect on internal temperature.

From this it was determined, for reasons of cost and simplicity of construction, that the optimised model will utilise two external cavity walls on the most exposed orientations and a solid 100mm heavy concrete wall on the most shaded orientation. The internal wall would also be 100mm heavy concrete, to reflect current common practice in Bangkok. ii.

Ceilings and floor

It is common practice in high rise residential buildings in Bangkok for there to be a false ceiling into which light fittings and other services can be installed. This is done for aesthetic reasons, but exposing the concrete of the structural ceiling, with its high thermal mass, reduced daytime temperatures by 0.2-0.5 K (see Appendix C4). As this change provides a thermal benefit, reduces cost and increases ceiling height it will be incorporated into the optimised model. The floor for the optimised model is similarly changed from the common timber finish to ceramic tiles and this provides an additional reduction of 0.1-0.2 K during peak hours (see Appendix C4). iii.

Furnishings

The theoretical background suggests that covering surfaces of high thermal mass reduces their ability both to absorb and radiate heat. This was modelled using built-in furniture (made with typical lightweight timber panels) which covered 80% of the wall and floor surfaces. The results (Appendix C5), showed that covering areas of high thermal mass in this way reduced their beneficial effect (0.20.3 K increased during peak hours). For this reason all the furniture incorporated into the optimised model will be free-standing, positioned a minimum of 50mm away from the walls and raised on legs 100mm off the floor.

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Optimised model specifications The optimised model evolved from the base case through the process documented in the preceding text of independently testing key factors – shading devices, building form, windows and materials.

The optimised model has the following specifications. Fixed horizontal shading device and combined vertical and horizontal (adaptive) louvres: three external facades, main facade south facing: windows open all day with a minimum ventilation rate of 15 ac/h day and night: two external cavity walls on the most exposed orientations and a solid 100mm heavy concrete wall on the most shaded orientation: internal wall of 100 mm heavy concrete: exposed concrete ceiling and ceramic floor tiles: both wall and floor covered with low thermal mass materials over 10% of their area. iv.

Results with optimised model

Compared to the base case, the optimised model shows a significant reduction in day time temperature throughout the week. On the 11th, which has the highest peak temperature, the reduction in daytime temperature is almost 1.5 K and on other days 0.7-1 K (Fig. 6.22).

As expected, the night time temperature increased by 0.3 - 0.8 K due to the heat radiating back out of the high mass materials into the cooler room. Even through the night time temperature using the high thermal mass strategies falls within the comfort band, significantly lower temperatures are desirable while sleeping.

The results show that exposed high thermal mass materials (and the other related strategies implemented) combined with 15 ac/h ventilation, can help reduce the daytime temperature to within the comfort band. However, there is a slight negative effect/temperature increase at night, a time when lower temperatures are desirable for sleeping. This leads to the conclusion that the high mass strategy is appropriate for living areas used during the day, but that for bedrooms the high thermal mass materials should be covered with lightweight materials to enable the room temperature to be more closely coupled with the falling air temperature.

Figure 6.22 Performance of base model compared to optimised model

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6.1.5 Occupancy People are a source of heat and increased humidity. The more people in a given space the more potential issues there are with internal temperature. High thermal mass materials can help absorb some of that heat (and radiate it out again during cooler periods). The simulations so far have allowed for 2 occupants present during the evening and overnight (a common pattern for working couples), with the apartment unoccupied during the day. i.

Increased occupancy

The impact of occupancy will now be explored using the optimised model, comparing 2 people present in the apartment during the evening and overnight, from 18:00 - 8:00, with 2 people present in the apartment all day and night, and two additional people at the weekend from 10:00 on 10 th to 19:00 on 11th. The weekend selected includes the day in the week with the lowest temperature (day10/03) and highest temperature (day 11/03).

As expected, the temperature rises both day and night with increased levels of occupancy, but by only by very small amounts, around 0.1K, up to 0.2 K with four occupants (Fig. 6.23). A reasonable explanation might be that the level of ventilation and high thermal mass help respectively to dissipate and absorb the heat gain. ii.

Interaction between thermal mass and day time window operation

In 6.1.3 (ii), in the section exploring natural ventilation, it was identified that the most effective strategy for lowering internal temperatures for occupants who are at work during the day is to leave the windows open all day. It was, however, also hypothesised that if occupants are present during the day they should close the windows when the external temperature is higher than the internal temperature. To test this hypothesis a simulation was carried out using the optimised model with the higher occupancy levels (2 all day/4 at weekends) For this simulation the windows are closed at 10.00 (when the outdoor temperature rises above the indoor temperature) and opened at 17.00 (when the outdoor temperature falls below the indoor temperature).

The results confirm the hypothesis (Fig. 6.24), showing a reduction in day time temperature of between 0.5-1.2 K. The hottest day (11/03) shows the greatest reduction (there were also four occupants on this day, as it fell on a weekend). The results indicate that, while windows should generally be open during the day, they should be closed when the outdoor temperature exceeds the indoor temperature. In this circumstance, a fan could be used to provide air movement, further reducing perception of temperature.

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Figure 6.23 Optimised model comparing two occupants overnight with two all day + four at weekends

Figure 6.24 Optimised model with windows open all day compared to windows closed from 10.00 – 17.00

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6.2 Balconies The potential benefits of balconies in the target context of Bangkok were discussed under theoretical background. Balconies can serve a range of useful functions; reduce heat gain to the adjacent living space and encourage apartment dwellers to be more connected to their surrounding environment.

Fieldwork confirmed that occupants enjoy spending the time on their balconies in appropriate conditions.

Due to regulatory constraints most balconies in high rise buildings in Bangkok are of the inset type.

For a small apartment the balcony will typically cover 20-30% of the faรงade, commonly adjacent to the kitchen area. Medium size apartments will typically have balconies that cover 40-60% of the faรงade, located adjacent to the living areas.

External balconies were not explored both because they are contraindicated by local regulations, and also because they are more exposed to solar radiation with consequent negative effects.

This section will therefore focus on the dimensions of balconies and how thermal comfort can be improved for occupants using them.

6.2.1 Dimensions of balconies Research identified that in the majority of cases balconies are fairly small (Chulakasyena, 2016).

Commonly, balconies in high rise buildings in Bangkok have a depth of just 1-1.3 m, just enough to accommodate the condenser unit of an air conditioning system. The noise and heat from the condenser discourages occupants from spending time on their balconies, and the small size means that the remaining space is often only sufficient for a pot plant or two, laundry or storage of miscellaneous household items.

The findings of this paper suggest that, with appropriate strategies, free running can be achieved, so the condenser unit can be eliminated from the balcony. The question then to be addressed is what dimensions are necessary for a balcony to become a truly useful and well used area of the apartment.

For a balcony to be truly useful, in the context of Thai social culture, the occupants must be able to eat on it, so it needs to accommodate a table that will accommodate two diners, and optionally (for a family or with guests) four. Neuferts (2002) diagrams of balconies (Fig. 6.25) show tables for four people but these are not dimensioned for dining, for which Neuferts lists a minimum comfortable width of 0.6m per diner (Fig 6.26). Given that it is more practical for balconies to be wider rather than deeper a sensible solution would be a table module of 1.2 x 0.6 m. (ideally of folding design). Such a table could be used in multiple layouts, as illustrated (Fig.6.27). The dimensions dictated by the table module, allowing for the necessary circulation space, indicate a balcony depth of 1.5m and a minimum width of 2.5 m.

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Figure 6.25 Recommened dimension of balcony for 3-4 people (Source: after Neufert, 2002)

Figure 6.26 Minimum comfortable width for dining area. (Source: after Neufert, 2002)

Figure 6.27 Examples of balcony layout with tables and chairs

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6.2.2 Thermal comfort on balconies As mentioned in section 3.1 Lechner (2009) has stated that, apart from air temperature there are three key factors that we can modify to help improve thermal comfort: air speed, relative humidity and mean radiant temperature.

For the users of balconies, direct solar radiation and mean radiant temperature are both important, and these are mediated by shading devices. The studies in section 6.1.2 have already explored the design of shading devices: the conclusions are also applicable to balconies so these studies will not be repeated.

Light colours, low thermal mass materials, high emissivity, high reflectivity, vegetation and water can all help reduce mean radiant temperatures on balconies. These factors require detailed analyses that could be the subject of further research but are considered outside the scope of this paper.

Ventilation reduces humidity and reduces the perceived temperature. Ventilation also increases the rate at which the balcony envelope loses stored heat by convection, especially during the night Ventilation is at once both one of the most important and most unpredictable of the major factors affecting thermal comfort. The focus of this section will be on enhancing ventilation on the inset type balcony.

Section 3.2.2 (ii) explained how wing walls can help to create pressure differentials which increase air movement. Their effectiveness in enhancing ventilation on balconies will be explored, testing both one panel and two panel installations. Panels of 0.5m will be used as these could be incorporated under the local regulations without impacting on permitted floor areas. 1m panels will also be tested to establish what if any advantages extra depth might deliver (Fig. 6.28).

For simulation purposes the balcony will measure 1.5 x 2.5 m (as concluded above), with metal railings allowing passage of air and light.

Two wind directions will be used for the simulations, representing the prevailing wind directions in Bangkok. These will be perpendicular to the panels and at 45 0 to them. A wind velocity of 2.2 m/s will be used, which is the average unobstructed wind flow for Bangkok.

Figure 6.28 Variations wingwall configurations.

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The results i.

(Fig. 6.29) With wind flow perpendicular to the panels

Base case (no wing wall) Wind velocity of 0.2-0.3 m/s, with general turbulence inside the balcony.

0.5 m, one panel Wind velocity of 0.5m/s on the windward side of the balcony and the area close to the panel. Wind velocity in other areas of 0.2-0.3 m/s accompanied by turbulence.

1.0 m one panel Wind velocity of 1.0-1.5 m/s distributed to most areas of the balcony.

0.5 m twin panels Wind velocity of 1-1.5 m/s on the windward side reducing to 0.5-0.7 m/s elsewhere, accompanied by turbulence.

1.0 m twin panels Wind velocity of 1.5-1.8 m/s in most areas accompanied by turbulence.

ii.

(Fig. 6.30) With wind flow at 450 to the panels

Base case (no wing wall) The wind inside the balcony was between 0.5-0.6 m/s with no turbulence 0.5 m one panel Wind velocity on the leeward side of the panel of 1.2-1.5 m/s and between 0.5-1.0 m/s elsewhere.

1.0 m one panel Wind velocity of almost 1.5-1.7 m/s throughout the balcony.

0.5m twin panels Wind velocity of 1.5-1.7 m/s around the wing walls and around 0.5-0.8 m/s elsewhere.

1.0 m twin panels Wind velocity around 1.5 m/s between the panels but 0.3-0.5 m/s elsewhere. It appears that the strong wind pressure on the leeward side combined with the short distance between the panels prevents the air flow reaching other areas of the balcony.

The overall best performance is achieved by a 1m single panel. If this solution is excluded by regulatory considerations, the second best overall option is 0.5m twin panels. Limitations of the software and the real world variability in wind direction and velocity mean that the results must be viewed as indicative rather than definitive, but they nonetheless confirm that wing walls will deliver enhanced ventilation to balconies, and identify the most promising configurations.

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Figure 6.29 Results of wind flow perpendicular to the panels.

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Figure 6.30 Results of wind flow at 450 to the panels.

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CHAPTER 7

Research outcomes

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Research has confirmed that a high proportion of the high rise residential buildings being erected in Bangkok replicate designs better suited to cold climates, with large glazed areas, no shading devices and little or no opportunity for cross ventilation. This renders air conditioning essential for the maintenance of thermal comfort. The research, literature review, field studies and analytic work reported in this paper have enabled the development of the following guidelines towards free running as a contribution to the design process for new high rise residential buildings.

7.1 Proposed Guidelines 7.1.1 Building form The main facades of the building should face south and north, to minimise solar radiation and maximise natural ventilation (Fig 7.1).

Building forms should be pierced with openings or voids to create apartments with at least two external and preferably three external walls to optimise opportunities for cross-ventilation (Fig 7.1).

The ground floor should be on pilotis where possible and open on at least two sides to create a transitional space with a range of useful potential functions (Fig 7.1).

7.1.2 Solar protection Analytical work confirms the clear benefits of shading devices in the climate of Bangkok, further identifying that the most effective shading device (or combination of shading devices) varies depending on the orientation of the faรงade. i.

Fixed shading devices

A fixed horizontal shading device of 0.5 m depth is recommended above glazed areas and balconies for all orientations, providing significant levels of protection from solar radiation without increasing the building footprint (as assessed under the local building regulations). (Fig. 7.2).

Vertical shading devices (also of 0.5m depth) are recommended on either side of wide glazed areas on north and south orientations only, where the benefit of the additional solar protection they will provide is judged to outweigh the lateral views they will obscure (Fig. 7.2).

Fixed perforated walls can provide good levels of additional solar protection while maintaining daylighting, but they block views and are thus best suited to utility rooms and rooms with outlooks that are not visually attractive. ii.

Adaptive shading devices

In addition to the fixed horizontal shading outlined above, further reductions in both direct and diffuse solar radiation (in particular) and internal temperature can be achieved on south, east and west facades using adaptive (moveable) shading devices. As a guide these should comprise louvres 100 mm deep with 100mm spacing between slats, to address both thermal protection and daylight distribution. Such additional shading is of marginal benefit for north facades.

Recommendations for each orientation are summarised in Figure 7.3. Consideration must also be given to ease of operation and cost of implementation. Care must be exercised and tests are recommended regarding the colour of the louvres, as although white will provide most reflection it can cause issues of excessive brightness (see Allzone building, section 4.2.5.) iii.

Facade protection

Heat gain through the faรงade can be reduced by the use of a double layer construction, where the high thermal mass of the structural wall is protected from solar radiation by an outer skin of timber or other suitable material of low thermal mass, the two separated by a 100mm air gap (Fig.7.4). This construction allows heat gain accumulated during the day in the envelope to be dissipated by convection overnight. Due to the relatively high cost/benefit ratio of this type of construction it should only be considered, if budget allows, after the implementation of the fixed and adaptive shading devices recommended.

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Figure 7.1 An example of proposed building form

Figure 7.2 proposed fixed shading devices

Figure 7.3 proposed adjustable fixed shading devices

Figure 7.4 Examples of external façade protection 86

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7.1.3 Ventilation Cross ventilation is the most efficient way to enhance natural ventilation. Cross ventilation requires at least two openings on different walls, and is the primary reason underlying the recommendations on form (see above) that propose that apartments have at least two and preferably three external walls.

Ceiling fans should be a standard fixture to enable occupants to create air movement in an energyefficient manner when conditions render natural ventilation insufficient to maintain thermal comfort. i.

Opening size/types

Window openings should be as large as possible, and for the most effective cross-ventilation, openings should ideally be on opposite walls. The total area of openings on opposing walls should be similar, although the shape and number of openings may vary (Fig. 7.5).

The performance of different window forms has not been tested, but research into precedent identified that the contemporary monsoon windows mentioned in section 4.2.3 can continue to provide natural ventilation during rainfall while preventing the ingress of water. Research is recommended into this concept, as is consideration of louvre windows (for high wind flows and some rain protection) and side hung windows (where they may be used to create a wing wall effect). ii.

Operation

Ideally windows should be closed when external temperatures exceed internal temperatures and open when exterior temperatures fall below internal temperatures. Automating this process would be helpful to optimise internal temperatures, but such a system would be both too complex and costly.

The simpler guidelines are to leave windows open at all times, save that if the occupants are present during the day and they become aware that external temperature exceeds internal temperature, they should close the windows while that condition persists.

7.1.4 Interior and internal layout i.

Dividing walls between apartments

Dividing walls should be designed to minimise sound transmission and heat transfer. The optimal solutions for achieving this need to be explored further but the fieldwork suggests that lightweight concrete could perform better than precast concrete for this application. ii.

Living areas

Living areas and any space primarily used during the daytime will benefit from an envelope of high thermal mass. The thickness of the materials is less critical that the exposure of surfaces of high thermal mass. This can be optimised by finishing walls with paint rather than wallpaper and painting concrete ceilings rather than finishing them with gypsum board or other material. In addition, furniture should be raised off the floor (e.g. on legs) and set away from walls. Floors should be ceramic tiled. iii.

Bedrooms

The surfaces of the internal envelope (wall, floor and ceiling) should be covered with materials of low thermal mass. Furniture should sit directly on the floor and where appropriate against the walls. iv.

Kitchens

Kitchens should be positioned so that they have external, opening windows, so that they enjoy natural daylight and can easily vent fumes and odours (Fig. 7.6). They should be separated from living areas to minimise migration of odours and the heat gain from appliances and cooking.

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Figure 7.5 An examples of proposed design for cross-ventilation (total area of 3m2 opening for both side)

Figure 7.6 An examples of proposed design floor plan for one bedroom unit

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7.1.5

Balconies

Inset balconies should be incorporated within the design, with a minimum dimension of 2.5 m wide by 1.5 m deep. The suggested depth – greater than is currently common – provides improved shading and solar protection and renders the space more usable (Fig7.6). Assuming the building is designed to be free-running, usability will be further improved by the absence of an air conditioning condenser.

A wind analysis should be carried out for the specific building under design and consideration given to the installation of twin wing walls 0.5 m deep, or a single (central) wing wall in circumstances where the building form is such that the larger dimension would not have negative consequences on the permitted floor areas of the building. Using glass for wing walls would minimise negative impact on views.

For protection from solar radiation, the conclusions in section 7.1.2 for shading devices are also applicable to the balconies.

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7.2 Subjects for further research 7.2.1 The applicability of the guidelines to other locations in Thailand Thailand stretches over 1,000 miles from north to south, with consequent variations in temperature ranges, rainfall patterns and other climatic factors. It would be useful to explore the degree to which the recommendations for Bangkok (in the centre of the country) are applicable elsewhere, and what variations might be appropriate.

7.2.2 Exploration of building forms that vary according to height to optimise benefits from prevailing wind conditions.

It was identified in section 3.2.2 (i) that different levels of a high rise building experience different wind flow phenomena. It would be informative to model building forms that varied over the height of the building to optimise the benefits of wind flow.

7.2.3 Internal permeable walls to increase opportunities for cross ventilation.

Cross ventilation has been identified as a key factor in improving thermal comfort and achieving free-running, but internal divisions may block air flows. Research into permeable walls/partitions could lead to solutions that allowed greater flexibility of internal layout without undue negative effects on cross ventilation.

7.2.4 Design of Insect netting to provide the best achievable combination of protection, wind flow and convenience of use.

Insect netting is essential in tropical climates, but has a negative effect on wind flow and can impact on the usability of the protected space. Research could lead to guidelines to optimise the compromise between the various factors.

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CHAPTER 8

Conclusions

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The continuing rapid growth of the city of Bangkok is driving the construction of high rise residential buildings. Bangkok is one of the world’s hottest and most humid cities and almost all these new developments are very largely dependent on air conditioning to provide acceptable thermal comfort to their occupants.

In addition, the combination of high demand and limited regulatory control can result in buildings whose design focus is on fast and low cost construction, often with lip service at best to environmental issues. High rise developments in Bangkok are commonly designed with single aspect apartments and double load corridors, in either I or L shape. As a consequence, the potential for cross ventilation is very limited. Large glazed areas are the norm, but due to both cost and the way the regulations calculate building footprint, shading devices tend not to be included. Balconies, which have potential to offer a much greater benefits to the occupants, are often of designs that render them of limited utility, simply housing air conditioning condensers and providing space for storage and laundry This research set out to clarify the issues, understand the context, seek guidance from theory, literature and precedents, carry out fieldwork to gather relevant data, propose and analyse potential approaches, then use the insights gained to develop guidelines for future high rise developments An early step was to understand aspects of the local building regulations that influence high rise building design. Amongst other factors, these have the practical effect of limiting the dimensions of shading devices that can be applied without the permitted building height (and thus floor area) being reduced.

Research into the local climate highlighted the key issues to be addressed. These can be summarised as a need to reduce the impact of solar radiation, both direct and diffuse, while maintaining desirable levels of daylight, and providing much enhanced ventilation. Thermal comfort zones for apartment occupants were investigated and appropriate parameters established.

Fieldwork confirmed the practical impact of issues of solar radiation and poor potential for ventilation, and also drew attention to concerns over internal layout, location of kitchens and usability of balconies.

Analytical work identified that fixed horizontal shading devices of 0.5m depth (to fall with regulatory limits) provide meaningful benefits in all orientations. Vertical shading for south and north facing facades is beneficial, although its benefits must be weighed against its potentially negative impact on lateral views. Adaptive horizontal louvres could effectively address issues of excessive direct and diffuse solar radiation and daylightiing in all orientations.

Moving away from common monolithic building forms to forms providing apartments with three external walls was found to greatly increase the potential for cross ventilation, a fundamental requirement for moving towards free-running in this climate. At the same time, increasing the number of external walls allowed greater flexibility of internal layout and enabled kitchens more easily to be provided with opening glazing for improved daylighting and venting of heat and odours. Raising buildings on pilotis enables ground floor lobby areas to be more open and reduces the requirement for air conditioning.

Simulations of varying combinations of window openings showed the desirability of large openings, with equal opening areas on both inlet and outlet walls. The impact of having windows open and closed in various scenarios was explored, resulting in the guidance set out in the guidelines above; in essence, that it is most beneficial for indoor temperature for windows to be open, except when outdoor temperature exceeds indoor temperature. It is recommended that ceiling fans be incorporated as a standard fitting to provide air movement when conditions mean that natural ventilation is inadequate.

Simulations were used to help select materials that would assist in improving the thermal comfort of the inhabitants. It was established that heat gain through the facade could be reduced by the use of external cavity walls, comprising a 100mm heavy concrete structural wall, separated from an outer skin of 25mm timber by a 100mm air gap, providing improved performance over conventional single 100mm walls. Internally, exposed surfaces of high thermal mass were found to be beneficial in 93

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reducing temperatures in living areas used during the day, while surfaces of low thermal mass were identified to be better in bedrooms, allowing a faster drop in temperature at night.

All of the best performing solutions were combined into an optimised model to be used as the basis for further simulations.

Test were carried out to identify the impact of occupancy on internal temperatures, using realistic scenarios of occupation. It was found that, as expected, occupants did cause the internal temperature to rise, but presumably as a consequence of the improved ventilation, the temperature change within the optimised model was minimal.

The research into balconies identified larger dimensions (2.5 m wide x 1.5 m deep) that would render balconies much more usable, especially with the removal of the currently ubiquitous air conditioning condenser unit. The installation of twin wing walls of 0.5 m depth was shown to provide enhanced ventilation in realistic wind conditions and would further improve the thermal comfort and usability of balconies.

The combination of all the temperature reduction strategies developed for the optimised model were shown to reduce the internal temperature by up to 5.5 k (on both the hottest day and night in the test period). This result, and the temperature graphs on other days, indicate that the internal temperature in the optimised model apartment would fall within the target comfort zone for all except the most extreme conditions. Even such exceptional conditions could be rendered acceptable by the use of electric fans, creating additional air movement and reducing the perception of temperature. The optimised model therefore forms the basis of realistic proposals for free-running apartments, both day and night.

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CHAPTER 9

References

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Ali, Z. (2013). On Site Review Report: The Met Tower, Pebble Bay Thailand Company, Thailand Antarikananda, P.,et al. (2006), Lessons from traditional architecture: Design for a climatic responsive contemporary house in Thailand. School of Architecture University of Portsmouth.

Baiche, B., Williman N (eds.). (2002). Neufert Architects’ Data 3rd ed. p 295. School of Architecture, Oxford Brookes University, UK. Baker, N., V. (2007). Natural ventilation strategies for refurbishment projects. Revival Technical Monograph 3 www.revival-eu.net Busch, J.F. (1992). A tale of two populations: Thermal comfort in air-conditioned and naturally ventilated offices in Thailand, Energy in Buildings Chirarattananon, S., et al. (2001). Daylight availability and models for global and diffuse horizontal illuminance and irradiance for Bangkok. Energy Program, Asian Institute of Technology, P.O.Box 4, Klong Luang, Pathumthani 12120, Thailand Cholasuek, C (2009), Assessing Environmental Performance of traditional Thai house. Term 2 research paper, AA E+E Environment & Energy Studies Programme. Architectural Association School of Architecture Graduate School. London.

Cholasuek, C. (2010) Sustainable Low-income community in Bangkok, MArch dissertation project 2008-2010, AA E+E Environment & Energy Studies Programme. Architectural Association School of Architecture Graduate School. London.

Chulakasyena, D. (2016). The functionality of balconies in hot and humid urban environments: An investigation into the functionality of balconies/attached transitional spaces in high rise housing in hot and humid urban environments. Term 2 research paper, AA E+E Environment & Energy Studies Programme. Architectural Association School of Architecture Graduate School. London.

CIBSE (2005). Natural Ventilation in Non-domestic Buildings. Applications Manual AM10. Chartered Institute of Building Services Engineers, London.

CIBSE (1999). Daylighting abd window design. Chartered Institution of Building Services Engineers, London.

Cohen, R (1997), Environmental criteria for naturally ventilated buildings, Halcrow Gibert Associates Ltd., Burderop Park, Swindon, UK. Erell, E., D. Pearlmutter, T. Williamson. (2011). Urban Microclimate Designing the Spaces Between Buildings. Earthscan, London.

Fanger, O (1993) How to apply thermal comfort models in practice. Thermal Comfort; Past, Present and Future conference, BRE. Givoni, B. (1994). Passive and Low Energy Cooling of Buildings. p27-30, 45-48Van Nostrand Reinhold.

Givoni, B. (1998) Climate Considerations in Building and Urban Design. p87-104, 230-232, 243, 256, 380-403, John Wiley & Sons, Inc., 605 Third Avenue, Newyork, NY 10158-0012 Jitkhajornwanich, K. (2006). Shifting comfort zone for hot-humid environments. Proceedings of 23rd International Conference PLEA 2006 (Passive and Low Energy Architecture). Geneva. Switzerland.

Koch-Nielsen, H. (2002). Stay Cool: A Design Guide for the Built Environment in Hot Climates. James & James (Science) Publishers.

Lechner, N. (2009). Heating, Cooling, Lighting (3rd edition): Sustainable design methods for architects, p 60-61, 64-65, 281. John Wiley & Son, Inc., Hoboken, New Jersey, USA. Littlefield, D. (eds) (2008). Metric Handbook: Planning and design data (3rd edition). Linacre House, Jordan Hill, Oxford OX2 8DP, UK Oesterle, E. et Al (2001). Double-skin facades: integrated planning. Prestel.

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Olesen, B.W., G.S. Brager. (2004) A Better Way to Predict Comfort: The New ASHRAE Standard 552004, University of California, Berkeley.

Oliveti, G. M.D. Simone, S. Ruffolo (2005). Solar contribution evaluation for building attached sunspace in the Mediterranean climate. International PLEA Conference. Passive and low energy cooling for the built environment. Santorini, Greece.

Papamanolis, N. (2005). The main construction characteristics of contemporary urban residential buildings in Greece. p391-398 Building and Environment 40. Elsevier.

Prajongsan, P. (2011). Enhancing natural ventilation, thermal comfort and energy saving in high-rise residential buildings in Bangkok through the use of ventilation shafts, School of Architecture, University of Liverpool, Liverpool.

Reynolds, S. (1992) Mechanical and electrical equipment for building (8th ed). p40. New York, John Wiley & Sons Inc. Sobin, H. J. (1980). Window Design for Passive Ventilative Cooling: An Experimental Study. Passive Cooling Applications Handbook, prepared for the Passive Cooling Workshop Amherst, Massachusetts.

Sirichanchuen, P. (2015) Low income community in Bangkok, Thailand: Design of an affordable and sustainable house for squatter life. MArch dissertation project 2008-2010, AA E+E Environment & Energy Studies Programme. Architectural Association School of Architecture Graduate School.

Szokolay, S. (2000). Dilemmas of Warm-Humid Climate House Design: Heavy vs. Lightweight + Cooling Effect of Ari Movement. Architecture, City, Environment, Proc. International PLEA 2000 Conference, Cambridge.

Szokolay, S. (2008), Introduction to Architectural Science: The Basis of Sustainable Design (2nd ed).

Architectural Press, London.

Tantasavasdi, C., J. Srebric, Q. Chen, (2001). Natural ventilation design for houses in Thailand.

Energy and Buildings, Rangsit Campus, Pathumthani, Thailand.

Tantipat, O (2011) Multi-Storey Housing in a Tropical City: Bangkok, MArch dissertation project 20092011, AA E+E Environment & Energy Studies Programme. Architectural Association School of Architecture Graduate School. London.

Taweekun, J., A. Tantiwichien, (2013), Thermal Comfort Zone for Thai people. Department of Mechanical Engineering Faculty of Engineering, Prince of Songkla University, Hat Yai, Songkhla, Thailand.

Tedkajorn, A. (2013) Self-sufficient Social Housing in Bangkok. MArch dissertation project 2011-2013, AA E+E Environment & Energy Studies Programme. Architectural Association School of Architecture Graduate School. London.

Tsichritzis, L (2014). Passive Solar Retrofit in Athens: The potential of Glazed Balconies. MSc dissertation project 2013-2014, AA E+E Environment & Energy Studies Programme. Architectural Association School of Architecture Graduate School, London.

Yannas, S. (1994). Solar Energy and Housing Design: Volume 1&2. Architectural Association, London, England.

Yannas, S. (Ed. 2000). Designing for Summer Comfort. EC Altener Programme. Environment & Energy Studies Programme, AA Graduate School, London.

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Lectures Baker, N. (10 Nov, 2015) Natural Ventilation. (Lecture to SED MSc & March Students). London, England: Architectural Association.

Brunelli G. (2015) Climate & Comfort studies. (Lecture to SED MSc & March Students). London, England: Architectural Association. 15 October.

Goncalves, J. (27 Jan 2016) Tall building. (Lecture to SED MSc & March Students). London, England: Architectural Association.

Ratanawaraha, A. (March 29, 2013) Shaping the Future of Thai cities. Harvard Kennedy School.

Yannas, S (11 Nov, 2015) dealing with heat: cool lessons from hot climates (Lecture to SED MSc & March Students). London, England: Architectural Association.

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Websites American Mosquito Control Association (AMCA). Frequently asked questions. Available at http://www.mosquito.org/faq (Access: 15 April 2016) City planning department, Bangkok Metropolitan Administration (2013). The Bangkok Comprehensive Plan. Bangkok , Thailand. Available at http://cpd.bangkok.go.th:90/web2/NEWCPD2556/The%20Bangkok%20Comprehensive%20Plan%20 2013_a4_pdf.pdf (Access: 10 April 2016) http://www.csccivil.co.th/view/22 (Access: 22 August 2016) www.reic.or.th (Access: 15 April 2016) http://web.nso.go.th/ (Access: 15 September 2016) https://www.wunderground.com/ (Access: 20 July 2016)

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CHAPTER 10

Appendices

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Appendix A Wind flow - Building scale Oedterle (2001) identifies three patterns of wind flow around a high rise building (Fig 10.1) The first is a horseshoe vortex effect at the base of the building where wind flowing off the windward face exerts a downward pressure and curls round on both sides of the building. According to Givoni (1998) this phenomena increases the mixing of air between ground level and above the urban canopy. As the latter is usually cleaner than the former, this results in an improvement in the air quality at street level around tall buildings. The horseshoe vortex effect can also increase the airflow speed around the building by up to 300% (Givoni, 1998) which in a hot and humid urban environment may be considered a positive impact.

The second pattern of wind flow identified by Oedterle (2001) is airflow around the body of the building, which may or may not be constant depending on the shape and consistency of the faรงade. There will also be some upward and downward air flow generated by the horizontal wind flow. The varying wind flows at different levels and locations of the building need to be taken into account when designing the building, not only in relation to natural ventilation but also because of resultant problems such as draughts, gusts and rain penetration. Rain penetration is a particular concern in tropical climates where it is beneficial to gain from the temperature drop resulting from rain but water ingress must be prevented.

A further effect of wind flow around the body of the building is the creation of pressure zones, caused when winds blowing against building compress the air in front of the walls facing the wind direction, and corresponding suction zones on the leeward walls where the pressure is reduced (Fig 10.2). This effect is dependent on the plan of the building and direction of the wind.

The third pattern of wind flow is top flow, where a large volume of air flows upwards and over the roof at the top of the building. This creates a negative pressure with a three-dimensional airstream.

This introduces potential for openings for outward airflow to enhance cross ventilation, and for the installation of wind turbines to catch the high velocity wind well above roof level.

These different wind effects at various heights mean that thought could usefully be given to varying the form of the building accordingly at different heights. This would be a useful subject for further research.

Where buildings of linear form (exceeding 30m in width) are placed one in front of another along their long facades, there is a benefit in creating openings either vertically or at ground level. This both minimises turbulence around the windward building and enhances wind flow to the leeward building (Fig. 10.3). According to Goncalves (2016), the wider the building the more the wind flows will be vertical (up and down), the narrower and the higher the building the more the wind flows will be horizontal (around the sides). Shading devices on the faรงade also can create significant obstructions to wind flow around the building

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Figure 10.1 Wind pattern (source: Oedterle, 2001)

Figure 10.2 Qualitative pressure distribution around a high-rise building (source: Oesterle, 2001)

Figure 10.3 Different forms of air gaps (source: Chao,Z.2006)

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Appendix - B

Appendix B1 Spot measurements – The Rhythm building (Room M)

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Appendix B2 Spot measurements – The U-Delight building (Room S)

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Appendix – C

Appendix C1 Comparison between different ac/h

Appendix C2 Comparison between different wall configurations

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Appendix C3 Comparison between different numbers of external (cavity) walls

Appendix C4 Comparison between rooms with gypsum ceiling, concrete ceiling, and concrete ceiling + ceramic floor

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Appendix C5 Comparison between room with and without furniture (80% coverage area)

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