Environmental performance and sustainable architecture a critical review in the context of singapore public housing 2

Part II Environmental Performance of Singapore Public Housing – Empirical Construction Chapter 6: Public Housing Development in Singapore 6.1 Prelude This chapter starts with a brief summary of Singapore public housing, followed by its literature review. In the context of this research, the literature review will focus on three aspects – socio-economics (including housing policies), housing design and environmental performance. It is observed that current literature on these aspects is grouped into three mainstreams of study: interrelationship of housing policies and socio-economic factors, housing design (built-form) and social aspects; and housing design and environmental performances. These three mainstream studies will then be positioned against the Integrated Framework for Sustainable Housing Design and Discourse. This will reveal some issues that have not been explored by existing literature, which limits the understanding of sustainable development of Singapore public housing. 6.2 6.2.1 The evolution of public housing development – a review Public housing in the 1960s Emerging in the midst of acute housing shortage, rapid population growth and extensive slum living conditions, public housing was initiated with the vision of being a prior condition to economic success. The housing policies in the first five years were to ‘provide low-cost housing for the lower income groups at rentals which [were] within their capacity to pay (HDB Annual Report, 1961). In 1964, when the acute housing shortage was eased, Home Ownership Scheme was introduced to target lower middle income group, enabling and encouraging them to own their own homes (HDB Annual Report, 1964); followed by allowing residents to use their Central Provident Fund to purchase public housing. In order to 115 reserve public housing for the needy residents, household income ceiling and household size and composition were controlled under housing policies. The dominant housing type during that period is the 1-room flats arranged linearly along a doubleloaded common corridor. 2- and 3-room flats were also built in a smaller portion, 25% and 30% of total housing built respectively in 1967. As a result of mass construction, the quantity of public housing grew, enabling 32% of the population housed towards the end of 1960s. Figure 6-1: Typical 1-room flats arrange along a double-loaded-corridor housing block in the 1960s. (Source: HDB (1970) First Decade in Public Housing 1960-69) 6.2.2 Public housing in the 1970s The second decade of public housing development was associated with high demand and change in the citizenry’s perspective and expectation of public housing as a result of resident affluence. As a response, housing policies were amended by raising the eligible household income ceiling and allowing smaller household size to qualify for public housing (HDB Annual Report, 1972). Furthermore, the Board extended its activities to cover housing for the growing middle income group through the establishment of Housing and Urban Development 116 Corporation (HUDC). Housing regulations were also lifted, e.g. allowing resident to install aircondition in their flat with written permission from the Board (HDB Resident Handbook, 1973). During this period, the construction of emergency 1- and 2-room flats gave way to the more spacious 3-, 4-, and 5-room flats. The design and construction process were improved with the introduction of standardisation and modularisation of building materials and elements (HDB Annual Report, 1975). The linear housing block design of the 60s was succeeded by single-loaded-corridor slab block and point block designs. Principles to self-efficient neighbourhood and new town were established and consolidated. Figure 6-2: Typical slab block and point block housing design in the 1970s 6.2.3 Public housing in the 1980s Public housing in the 1980s was developed with the emphasis on promoting a sense of community and identity (Perry et al, 1997). Over the years, the socio-economic characteristics of HDB residents and their lifestyle had undergone substantial changes. Incomes increased. Household structure, size of families and demographic profile of the population, was constantly in a state of changes. These social changes required the implementation of new 117 policies. Major areas of review included the need to preserve the Asian tradition of grandparents living with or near their married children and grandchildren. The policies also have to meet the changing demands of Singaporeans and certain categories of Permanent Residents as well as non-citizens for housing at reasonable cost. The relaxation of rules on mutual exchange of home ownership flats to give greater resident mobility. In addition, the qualifying household income ceiling was constantly under review. These policies kept the percentage of population living in public housing constantly increased, reaching to 88% of total population in 1989 (HDB Annual Report, 1989). Public housing flat designs in this period were marked with new design of 3-, 4-, and 5-room model A with larger areas and quality. Executive apartments were also introduced to cater for the upper-middle income group. On the other hand, improving quality of existing housing was continuously carried out since the early 1970s. In promoting the identity for housing estate, the design of high-rise housing incorporated local traditional architectural and building elements. In promoting a sense of community, common public spaces within housing estates were given more attention. Public housing embarked upon new role of enhancing social integration in this decade. Figure 6-3: Incorporating local traditional architectural element and the focus on community development (Source: HDB, 1988) 118 6.2.4 Public housing in the 1990s The emphasis of public housing in the 1990s was on service and quality development and environment (Yuen et al, 1999). The socio-economic characteristics in the 1990s were the continued decrease in household size, rapid increase in resident affluence and resident mobility. Housing policies were transformed to both meet and shape these changes, through raising the qualifying household ceiling income, allowing singles to own a 3-room or smaller flat, and allowing second air-condition to be installed in public housing flat. As a response to the trend of smaller household size, public housing design in the 1990s had their flat size reduced twice in 1993 and 1997, resulting in smaller flat size of up to 20 square metres compared to those in the 1980s. The prominent activity of public housing in this decade was taken up by upgrading programmes, which were proven successful in providing better living environment in older housing estates without the need to relocate residents and break up their established community ties. Figure 6-4: Upgrading programme in older public housing estate and the use of Space Adding Item (Source of left picture: HDB, 2000) 119 6.2.5 Public housing in the 2000s Public housing after the year 2000 has been marked with the attempt to create sustainable living environment. The vision of HDB is to research and develop ‘HDB Eco-Town’ that would strive for the best practices to meet environmental and community needs (HDB Annual Report, 2002). Along side with this vision, public housing was facilitated with lighting dual circuit system in the public areas of housing blocks, to be automatically switched off after midnight to conserve energy (HDB Annual Report, 2001). Rooftop garden, equipped with a wide range of recreational facilities, was introduced with purposes of (1) greening, softening and reducing urban heat island effects of the densely built environment (Wong et al, 2002), and (2) providing comfortable communal areas for the residents. Furthermore, experiment on increasing the height of public housing (up to 40 storey height) has also been being carried out, to be higher land-use efficiency. Studio apartments with elderly-friendly design features were introduced as a respond to the aging population and wealthier senior residents. In brief, the trend of public housing development since its inception can be traced in a process of being merely providing sheltering for low-income residents, to better respond to resident affluence and aspirations, to enhancing social integration, and finally toward sustainable development. Figure 6-5: Higher high-rise living and better environmental responsive housing design 120 6.3 Literature on public housing – a review Existing literature on public housing covers many aspects related to public housing development, i.e. socio-economic aspects, housing policies, housing design, construction methods and techniques, management, real estate, environmental performances, etc. In this research, the literature review, besides concentrating on HDB activities in public housing development, focuses on aspects – socio-economics (including housing policies), housing design and environmental performance. Literatures on these aspects can be grouped into three mainstreams of study: the interrelationship of housing policies and socio-economic factors, housing design (built-form) and social aspects; and housing design and environmental performance. 6.3.1 Interrelationship of housing policies and socio-economic factors For the last four decades in Singapore, there has been a progressive integration between economic growth, social stability, and urbanisation process through public policies (Castells et al, 1990). Public housing policies, as both responding to, and preventing the extremes of, the socio-economic variables through times, have been under constantly reformations. There are two levels of public housing policies. At macro level, the policies address the physical environment, i.e. high-rise high-density development and comprehensive planning of new town, and the national interest in promoting home ownership. At micro level, housing policies are concerned with estate management, i.e. ‘maintaining the housing estates and educating the occupants of its housing to the requirements of high-density high-rise living’ (Tan, 1998). Developing mass public housing towards high-rise high-density direction aims at ‘achieving as high a residential density as possible, within the limits of social acceptability, environmental amenability and economical constraint’ (Yeh, 1975). This policy has resulted in social characteristics that are distinct from traditional landed property residents. In the early stage, 121 social transformations due to high-rise living were quite pessimistic. The main problem was the weak bond between the individual and social structure, associating with little sense of neighbourhood and pervasive sense of insecurity (Riaz, 1977; Spiro, 1977; and Tai, 1977). These social issues, however, have gradually been alleviated as indication of higher sociable interactions in public housing estates (Tai, 1989; HDB, 2000). Public housing policies related to home ownership and housing allocation aim to promote socioeconomic stability for the residents and to act as a political instrument. The concept of homeownership has been understood as providing residents not only a sense of pride, but also the incentive to look after their home (Sim et al, 1993). In discussing political legitimacy and housing, Chua (1997) juxtaposes Singapore’s public housing programme to those of the US and the ex-socialist central European countries. While the US programme characterises its housing as a consumer good and the ex-socialist European countries idealise housing as a social right, Singapore public housing avoids the drawbacks of the two system and is able to ‘institutionalise universal provision without eliminating the ability of market forces to exercise discipline on housing consumers’ (Yuen et al, 1999 in the summary of [Chua, 1997]). The mutual interaction between socio-economic factors and housing policies is brought up in Yeh’s study (1985), which highlights the interrelationship among household changes and housing policies. That is the patterns of household growth directly affecting housing demands, which in turn has policy implications for housing supply (Yeh, 1985). Housing policies related to estate management associate more to the requirements of highdensity high-rise living. ‘Such restrictions are imposed either for the protection of the common property, preservation of the outward appearance of the buildings, safety of occupants of other flats, safety of the buildings, or for the preservation of the peaceable enjoyment by the other occupants of their own flats and the common property’ (Tan, 1998). 122 These estate management policies have, however, socio-economic consequences to the residents. For instant, the Estate Renewal Programme since the late 1970s has been considered successful in terms of safeguarding resident community ties, social stability, and infrastructure utilisation through reducing resident mobility (Lau, 1998 & HDB Corporate Newsletter, June 2000). In general, housing policy started with restrictive rules and regulations to safeguard the housing provision to the right categories of residents. This aimed to maintain certain orders and principles in public housing estates during the confusing stage of resident in their lifestyle transformation. These housing policies and regulations have gradually been lifted and relaxed as a response to socio-economic changes, e.g. alleviation of acute housing needs, the continuous growth of Singapore wealth, more and higher educated residents, and household structure changes. Pugh’s paper on ‘Housing and Development in Singapore’ commends the effectiveness of housing policies and traces these successful policy transformations: Firstly, ensure a flow of resources and finance into housing from the saving of the community; secondly, create a statutory development corporation, complete with powers and resources to plan and build social housing; thirdly, relate the access to that housing to a wide range of income group; fourthly, use home-ownership for general social, economic, and political purposes; fifthly, not be too perturbed by some orthodox economists argument; sixthly, ensure an adequate supply of lowpriced land in growing urban areas; and finally conceive and operate housing policy and other social policies as an integral part of the development. (Yuen, 1999 in the summary of [Pugh, 1985]) 123 decades, public housings were designed rigorously to North-South orientation. This resulted in steady higher scores in compared to public housing design in later decades. Thermal Attribute (GBC score) 0.4 -0.5 0.4 -0.5 0.8 0.4 -0.8 -0.5 -0.1 -0.8 -0.5 -0.6 -0.8 -0.3 -0.5 -1 -2 1960s 1970s 1980s 1990s 2000s Figure 8-11: Thermal comfort of the case study public housings (GBC score) 8.5.3 Daylighting Two criteria, provision of daylighting in living/kitchen area and potential glare in dwelling units, are under consideration in daylighting performance category. For the first criterion, average Daylight Factor (%) of the living and dining areas of the typical dwelling unit on the lowest typical floor will be measured. Daylight Factor is defined as 'the ratio of indoor to outdoor horizontal illuminance, excluding direct sunlight' (GBTool User Manual , 2002) and is calculated based on the following formula (as extracted from GBTool worksheet): DF = [Aw x Vt   v] Where: ✁ ✁ / 2.5 x 100 x Ais x (1 - Ris) DF Daylight Factor (%). Aw Area of window in sample space (m2). Vt Average visual transmissibility of window (%). v (16) Visible angle of sky at window (degree). Visible angle of sky is 90 deg. minus reduction for overhangs and nearby buildings. 173 Ais Area of interior surfaces (walls, floors, ceilings) of typical primary space on the lowest typical floor facing (m2). Ris Reflectance of interior surface. Typical reflectances = 0.7 for light colours, 0.5 for typical mild colours, 0.3 for dark coloured rooms. The second criterion of daylighting category measures the potential for glare in dwelling units. It is noted that 'direct and reflected glare can reduce occupant satisfaction (…) and initiate action such as covering windows that ultimately reduce the amount of useful daylight to the building interior.' GBTool ( User Manual, 2002). The measurement bases on the design features that reduce the likelihood of glare, e.g. openings that are recessed from their external wall(s), common access corridor(s), sun shading devices and the like. The integration of the above two criteria's assessments form daylighting performance category. By compiling the assessment outcomes of all the case studies, the indicative daylighting performance trend of public housing development is revealed (Figure 8-12). Da ylighting Daylighting (c ategory s core) 0.7 0.4 0.3 -0.1 -1 -0.3 -0.5 -0.7 -0.8 0.2 -0.5 -0.6 -0.9 -1.2 0.4 -0.5 -0.3 -0.2 0.3 Daylight fac tor 0.1 -0.2 -0.4 -0.2 -0.5 -0.2 -1.7 P otential glare 1960s 1970s 1990s Premium B Premium B & C Ex e. Premium A & B 4-R A & 5-R 4-R A & 5-R 4-R A & 5-R 4-R A & 5-R 3-R I Upg 3-R NG Upg Ex e. A prt. Ex e. Mais . Ex e. A prt. 5-R I Ex e. Mais 5-R A HUDC A prt. 4-R A 1980s HUDC Mais. 5-R A 3- & 4-R A 5-R I 4-R S 4-R NG 3- & 4-R NG 2-R I 3-R NG 3-R I 1-R I 2-R S -2 2000s Figure 8-12: Daylighting performance of the case study public housings (GBC score) 174 8.5.4 Noise and acoustics The criterion under noise and acoustics category is noise attenuation through the building envelope. This criterion acknowledges that most penetrated external noise nuisance is through windows, and assesses 'whether the glazing system is effective in reducingthe transmission of externally generated noise' (Cole and Larsson, 2002, GBTool User Manual). The measurement bases on the Sound Transmission Class of windows, which are identical among all case studies. 8.5.5 Indicative indoor environmental quality trend of public housing The scores of all the above categories – air quality and ventilation, thermal comfort, daylighting, and noise and acoustics – after taking weighting system into account, constitute the scores of indoor environmental quality performance issue. The compilation of the case studies' assessment outcomes reveals the indicative indoor environmental quality trend of public housing (Figure 8-13). Trendline of Indoor E nvironm ental Quality P erform ance -0.1 0.2 0.2 0.3 -0.1 0.8 0.2 0.4 0.3 0.2 0.2 0.2 0.1 -0.1 Premium B & C 0.1 Premium B Premium A & B 0.9 0.4 4-R A & 5-R -0.2 0.1 4-R A & 5-R 0.7 0.1 4-R A & 5-R 0.9 Exe. A prt. 0.6 Exe. Mais HUDC A prt. 0.9 HUDC Mais. 0.9 0.4 5-R A 4-R S 4-R A & 5-R -1 1960s 1970s 1980s Exe. 3-R I Upg 3-R NG Upg Exe. A prt. 1990s Exe. Mais. 5-R I 5-R A 4-R A 3- & 4-R A 5-R I 4-R NG 3-R NG 3- & 4-R NG 2-R I 3-R I 1-R I 2-R S -2 2000s Figure 8-13: Indicative trendline of indoor environmental quality in public housing evolution (GBC score) 175 8.6 Quality of service The environmental performance issue of service quality, in the customised GBC, takes into consideration of six categories – flexibility and adaptability, controllability of systems, maintenance of performance, privacy and access to views, quality of amenities and site development, and impact on quality of service of site and adjacent properties. 8.6.1 Flexibility and adaptability The assessment of flexibility and adaptability category includes four criteria – suitability of layout for structure and core for major changes in future uses, suitability of floor height for major changes in future uses, floor loading capacity for other uses, and adaptability to future changes in type of energy supply. All the case studies receive almost similar scores for all four criteria. All public housing designs have the flexibility for changes in future uses – e.g. converting dwelling units into hotel rooms – with alike renovation efforts. For the criterion of suitability of floor height for changes in future uses, it is acknowledged that the higher floorto-floor height the more adaptable the building can be for other uses. Regarding this aspect in the evolution of public housing designs, there are two dimensions for floor-to-floor heights – 2.7m for those case studies built in the 1960s and 1970s, and 2.8m for those case studies built in the 1980s or later. All case studies are adaptable to new type of energy supply (by choice of switching between traditional and renewable energy) with electrical rewiring required 8.6.2 Controllability of systems This performance category aims to safeguard the residents' capability to control over lighting, heating and cooling in dwelling units. All case study housing designs allow this capacity to the residents in equal manner. 176 8.6.3 Maintenance of performance This category includes two criteria, each of which ramifies into two sub-criteria. The first criterion focuses on the potential to maintain performance of building systems, which is measured in two sub-criteria – the access to building elements and materials for maintenance and replacement, and the ability to maintain critical performance parameters under abnormal conditions. All case studies receive the same score for the first sub-criterion, as all the building elements and materials are locally standardisation, and area commonly and easily accessed to for replacements when required. As for the second sub-criterion, there are two groups of scores – lower score group for the case study housings built without household shelters and higher score group for the case study housings built with household shelters. Household shelter was introduced in early 1990s to provide protection to the residents for civil defence purposes and to be used as a pantry/store during normal time (HDB, 1995). The second criterion looks into metering and monitoring of performance, which is measured based on two sub-criteria – monitoring of energy usage and provision of leak detection system for water and gas supplies. All case studies receive the same score for these two sub-criteria. 8.6.4 Privacy and access to views This performance category includes two criteria – visual access to the exterior from living area, and visual privacy from the exterior in living and sleeping areas of dwelling units. Measurement of the first criterion bases on the unobstructed distance from windows of principle living areas of typical dwelling units. Measurement in the second criterion bases on the distance of available point that horizontal and downward views are available of the interior of bedroom and living areas of number of percentage of dwelling units of the building. Figure 8-14 shows the compilation of assessment results (or the indicative trend) of all case studies under privacy and assess to views category. According to this indicative trend, the privacy and assess to views performance of public housing development was, in general, 177 relatively low in the early years. The performance trend improved in the 1990s – especially in terms of visual assess to the exterior, but excepting the two upgraded projects. This trend, however, decreased from the year 2000 onwards. P riva cy a nd Asse ss to V ie w (G BC sco re ) 4.5 2.5 2.5 2.5 2.8 0.6 -0.1 -0.3 0.4 0.2 0.5 0.2 1.5 1.4 1.3 0.5 -0.2 V is u a l a c c es s to th e e x te rio r (G B C s c ore ) -0.5 -0.7 19 60 s 19 70 s 19 80 s 19 90 s Pre mium B Pre mium B & C Ex e. Pre mium A & B 4-R A & -R 4-R A & -R 4-R A & -R 4-R A & -R 3-R I Up g 3-R NG Up g Ex e. A p rt. Ex e. Ma is . Ex e. A p rt. 5-R I Ex e. Ma is 5-R A HUDC A prt. 4-R A HUDC Mais . 5-R A 3- & -R A 5-R I 4-R S 4-R NG 3- & -R NG 2-R I 3-R NG 1-R I 2-R S 3-R I -1 -2 P rivac y an d A c c e s s to V iew s (s ub tota l G B C s c ore ) V is u a l p riva c y from th e e x te rio r (G B C s c ore ) 20 00 s Figure 8-14: Visual privacy and access to view of the case study public housing (GBC score) 8.6.5 Quality of amenities and site development There are two criteria to be assessed under this performance category. The first one measures the site amenities for shade, relaxation and play for residents, with the objective to create pleasant communal spaces that will be highly utilised by the residents. The second criterion measures the quality of parking area, with objective to minimise the environmental adverse affects of on-grade parking areas. In responding to higher residents'aspiration over times, both the quality of site amenities and quality of parking area are improved over the years. This has been reflected in the indicative performance trend as shown in Figure 8-15. Q u ality o f Am e n itie s an d Site De v e lo p m e n t .4 .1 .2 96 s 97 s 98 s 99 s -0 .4 S ite a me n itie s .5 Q u ality o f p ar king Pre miu m B & C Pre miu m B Ex e . Pre miu m A & B -R A & -R -R A & -R -0 .7 -R A & -R -R I Up g -R NG Up g -0 .7 -R A & -R -0 .1 -0 .4 Ex e . Ma is . Ex e . Ma is -R I Q u ality o f A me nitie s a nd S ite De v elop me nt Ca te ro g y .6 -0 .6 -R A .2 .6 -1 HUDC A pr t. -R A -1 HUDC Mais . -R A -0 .9 - & 4- R A -1 -R S -1 -R I -1 .1 -R NG -1 .3 - & 4- R NG -1 .5 -R NG -R I -1 .7 -1 .6 -R I -R I -1 .1 -R S -1 -1 .6 -0 .7 Ex e . A p rt. .6 -0 .1 Ex e . A p rt. -2 .3 L in ea r (Q u a lity of A me nitie s a nd S ite De v elop me nt Ca te ro g y ) 00 s Figure 8-15: Indicative trendline of quality of amenities and site development in public housing evolution (GBC score) 178 8.6.6 Impact on quality of service of site and adjacent properties There are three performance criteria to be assessed under this category. The first criterion concerns the adverse wind conditions at grade around high buildings. The assessment bases on the height of the case study housing in compared to surrounding and design features to reduce the adverse wind conditions, e.g. the provision of void-deck. The second criterion concerns on impact on access to daylight of adjacent property. Its measurement bases on the vertical angle measured from the building line on the ground of the nearest adjacent property to the roof line of the case study housing. The larger the angle, the less score the case study housing will get (Figure 8-16). The third criterion takes into account the impact on solar energy potential of adjacent housing block. Its measurement bases on the percentage of the southerly facing building façade of an adjacent property on the North of the case study housing that is shaded by the case study housing at 12 noon on winter solstice. Although exposed to sunlight is unfavourable in Singapore hot climate, the criterion is considered applicable in the credit of potential solar energy collection in the future. Nonetheless, all case studies receive the same score for this criterion due to the equatorial location of Singapore that 0% of the southerly facing façade area of the northern adjacent property of the case study is shaded at 12 noon. Figure 8-16: The vertical angle to assess the impact on access to daylight of adjacent property (Source: GBTool V1.81) 179 Figure 8-17 shows the compilation of the assessment outcomes of all the case studies to give indicative performance trend under this performance category. According to this trend, the performance scores for the impact on quality of service of site and adjacent properties reduce slightly after decades. The main cause is the decreasing indicative trend of the impact of assess to daylight of adjacent property due to the trend of building higher density and thus narrower spacing among housing blocks. Impact on service quality of site and adjacent properties 1.5 0.3 0.8 0.8 0.5 0.8 0.8 -0.1 0.8 -0.7 -0.6 -0.9 A dverse w ind conditions at grade 0.8 -0.2 -0.8 -1 -1 -0.8 -0.8 -0.8 -1 Impact on access to daylight of adjacent property 1960s 1970s 1990s Premium B Premium B & C Exe. Premium A & B 4-R A & 5-R 4-R A & 5-R 4-R A & 5-R 4-R A & 5-R 3-R I Upg 3-R NG Upg Exe. A prt. Exe. Mais. Exe. A prt. 5-R I Exe. Mais 5-R A HUDC A prt. 4-R A 1980s HUDC Mais. 5-R A 3- & 4-R A 5-R I 4-R S 4-R NG 3- & 4-R NG 2-R I 3-R NG 3-R I 1-R I 2-R S -2 Linear (Impac t on service quality of site and adjacent properties ) 2000s Figure 8-17: Indicative trendline of impact on service quality of site and adjacent properties in public housing evolution (GBC score) 8.6.7 Indicative service quality trend of public housing The scores of all the above six categories – flexibility and adaptability, controllability of systems, maintenance of performance, privacy and access to views, quality of amenities and site development, and impact on quality of service of site and adjacent properties – after taking weighting system into account, constitute the score of service quality performance issue. The compilation of the case studies' assessment outcomes reveals the indicative service quality performance trend of public housing as shown in Figure 8-18. 180 Trendline of S ervice Quality P erform ance -0.2 -0.4 0.4 -0.2 0.8 -0.1 0.1 0.8 0.3 1.3 0.8 0.5 1.3 0.8 0.2 -0.2 -0.2 3-R I Upg -0.3 0.7 4-R A -0.4 3-R I -0.2 2-R S 0.8 0.3 3- & 4-R A 3-R NG Upg 1.3 1.2 0.2 0.2 0.2 0.1 0.6 -1 1960s 1970s 1980s 1990s Premium B Premium B & C Ex e. Premium A & B 4-R A & 5-R 4-R A & 5-R 4-R A & 5-R 4-R A & 5-R Ex e. A prt. Ex e. Mais. Ex e. A prt. 5-R I Ex e. Mais 5-R A HUDC A prt. HUDC Mais. 5-R A 5-R I 4-R S 3- & 4-R NG 4-R NG 2-R I 3-R NG 1-R I -2 2000s Figure 8-18: Indicative trendline of service quality in public housing evolution (GBC score) 8.7 The indicative overall environmental performance trend In summary of the environmental performances of public housing case studies over four and half decades, there has been a sharp fall in the two indicative trends of resource consumption and environmental loading performance issues, a slightly decrease in the indicative indoor environmental quality performance trend, and an increase in the indicative quality of service performance trend. As a result of the combination of the four indicative environmental performance issue trends, with weighting taken into consideration, the indicative trend of total environmental performance of public housing has been constructed (Figure 8-19). 5.0 Total Score 4.0 3.0 2.0 1.6 1.4 1.3 1.2 1.4 1.3 1.5 Res ource Cons umption 1.6 0.8 1.0 1.1 1.5 0.8 0.7 1.3 0.7 0.9 0.3 0.8 0.6 0.9 0.3 0.3 0.0 -0.1 0.2 0.3 0.3 0.1 -0.1 0.1 0.5 Env ironmental Loading 1960s 1970s 1980s Premium B & C Premium B Premium A & B Exe. 4-R A & 5-R 4-R A & 5-R 4-R A & 5-R 4-R A & 5-R 3-R NG Upg 3-R I Upg Exe. A prt. 1990s Exe. Mais . Exe. A prt. Exe. Mais 5-R I 5-R A HUDC A prt. HUDC Mais . 4-R A 3- & 4-R A 4-R S 5-R A 5-R I 4-R NG 3- & 4-R NG 3-R NG 2-R I Service Quality 3-R I -2.0 1-R I Indoor Env ironment Quality 2-R S -1.0 Linear (Total Score) 2000s Figure 8-19: Indicative trendline of total environmental performances in public housing evolution (GBC score) 181 This indicative total environmental performance trend shows a general decline in performances of public housing development, from an approximate score of +1.5 in the 1960s to an approximate score of in the recent years. 8.8 Clarifying the assessment assumptions and results 8.8.1 The message of the indicative environmental performance trends The indicative total environmental performance trend of public housing, as constructed in previous section, shows a fall in environmental performances of public housing during its evolution. According to this indicative trends, the total environmental performance scores range from an approximate +1.5 in the 1960s to an approximate in the recent years. The highest overall environmental performance score of +1.6 is found in case study number 01 and 08 – 1-room flat housing block in the double corridor slab block layout in the 1960s, and 5-room flat point block in the 1970s respectively. The lowest overall environmental performance score of -0.1 is found in case study number 23 and 28 – a mixed of 4-room model A and 5-room Improved housing block, and a mixed of Premium Apartment type A and type B housing block respectively (both are built after year 2000). Indicative trendline of overall environm ental performance (GB C score) 5.0 4.0 1.4 1.3 1.5 1.6 0.8 1.1 1.5 0.7 0.8 1.3 0.7 0.3 0.9 0.6 0.8 0.9 0.3 0.3 0.0 -0.1 0.2 0.3 0.1 0.3 27: Exe. 1.2 26: 4-R A & 5-R 1.3 25: 4-R A & 5-R 1.4 24: 4-R A & 5-R 1.6 1.0 21: 3-R I Upg 2.0 22: 3-R NG Upg 3.0 -0.1 0.1 0.5 -1.0 1960s 1970s 1990s 29: Premium B 30: Premium B & C 28: Premium A & B 23: 4-R A & 5-R 19: Exe. A prt. 20: Exe. Mais. 18: Exe. A prt. 16: 5-R I 17: Exe. Mais 15: 5-R A 14: HUDC A prt. 12: 4-R A 1980s 13: HUDC Mais . 10: 5-R A 11: 3- & 4-R A 08: 5-R I 09: 4-R S 07: 4-R NG 06: 3- & 4-R NG 04: 2-R I 05: 3-R NG 03: 3-R I 01: 1-R I 02: 2-R S -2.0 2000s Figure 8-20: Chart showing the indicative trendline of total environmental performance 182 The total environmental performance of each case study is constituted by environmental issues: resource consumption, environmental loadings, indoor environmental quality and service quality. The indicative resource consumption trend shows a decline in trend, from the general score of +2 in the 1960s to the general score of in year 2000 onwards. As observed from the constituting indicative trends, the main reason for this decline in indicative resource consumption trend is the rapid increasing trends of energy and of water consumptions (Figure 8-21). The slightly increase in the indicative performance trend of land use and ecological value of land (Figure 8-3) constitutes counteracting the decrease trends. This only contributes in reducing but not reversing the overall trendline of resource consumption performance. Indicative trend line of reso urce co nsum p tion (G B C score) 2.3 1.4 2.5 1.8 1.6 1.5 1.3 0.6 0.8 0.8 0.2 0.6 0.9 0.9 0.1 0.5 -0.2 0.1 0.4 0.1 0.3 -0.2 29: Premium B 2.4 28: Premium A & B 0.4 1960s 1970s 1990s 30: Premium B & C 27: Exe. 26: 4-R A & 5-R 25: 4-R A & 5-R 24: 4-R A & 5-R 23: 4-R A & 5-R 21: 3-R I Upg 22: 3-R NG Upg 19: Exe. Aprt. 20: Exe. Mais. 18: Exe. Aprt. 16: 5-R I 17: Exe. Mais 15: 5-R A 14: HUDC Aprt. 12: 4-R A 1980s 13: HUDC Mais. 10: 5-R A 11: 3- & 4-R A 08: 5-R I 09: 4-R S 07: 4-R NG 06: 3- & 4-R NG 04: 2-R I 05: 3-R NG 03: 3-R I 01: 1-R I -2 02: 2-R S -1 2000s Figure 8-21: Chart showing the indicative trendline of resource consumption performance Similarly, the indicative trend of environmental loading performance has also been progressively lower with time, starting from score of higher +2 in the 1960s to approximately +1, and finally to more or less in year 2000 onwards. The constituting reasons are both the decrease in performance trends of the three airborne emissions related to energy consumption, and of the environmental impact on site and adjacent properties. The slightly increasing trends in liquid effluent performance and solid waste facilities contribute in only reducing, but are unable to reserve, the overall environmental loading performance trend. 183 Indicative trend line of e nvironm ental load ing (GB C sco re ) 1.5 1.5 1.9 2.1 1.6 2.4 1.9 1.3 2.2 1.5 1.4 1.2 0.9 1.1 0.5 0.3 -0.3 -0.1 26: 4-R A & 5-R 25: 4-R A & 5-R 2.1 24: 4-R A & 5-R 0.4 -0.4 0.5 1960s 1980s 1990s 30: Premium B & C 29: Premium B 27: Exe. 28: Premium A & B 22: 3-R NG Upg 21: 3-R I Upg 19: Exe. Aprt. 20: Exe. Mais. 18: Exe. Aprt. 16: 5-R I 17: Exe. Mais 15: 5-R A 14: HUDC Aprt. 12: 4-R A 13: HUDC Mais. 10: 5-R A 1970s 11: 3- & 4-R A 08: 5-R I 09: 4-R S 07: 4-R NG 06: 3- & 4-R NG 04: 2-R I 05: 3-R NG 03: 3-R I 01: 1-R I 02: 2-R S -2 23: 4-R A & 5-R -1 2000s Figure 8-22: Chart showing the indicative trendline of environmental loading performance With regards to indoor environmental quality, it is noted this indicative trend has slightly declined after decades of public housing development. While there is no distinctive ascending or descending trend in the noise and acoustics category, there is a slightly increase in natural ventilation performance trend and in daylighting performance trend, but a rapid decline in thermal comfort performance trend. It is the significant fall of thermal comfort performance trend that have negatively influence to the indicative overall indoor environmental quality performance trend. The rather consistent high scores of most case studies in the 1960s and 1970s are due to their consistent high scores in the constituting thermal comfort performance, in which their solar radiation impacts are minimised attributed to the rigorous design of North and South orientation. This is also applied in the two upgraded case studies in the late 1990s, which inherit their original building design and layout in the 1960s and 1970s. Indicative tre ndline of indoo r environm ental q uality (GB C score) 0.1 -0.1 0.2 0.2 0.3 -0.1 0.8 0.2 0.4 0.3 0.2 0.2 0.2 0.1 29: Premium B 0.9 28: Premium A & B 0.4 27: Exe. 0.1 26: 4-R A & 5-R 0.1 25: 4-R A & 5-R 0.7 -0.2 24: 4-R A & 5-R 0.9 18: Exe. A prt. 0.6 17: Exe. Mais 16: 5-R I 0.9 15: 5-R A 0.9 14: HUDC A prt. 0.4 13: HUDC Mais. 10: 5-R A 09: 4-R S 23: 4-R A & 5-R -0.1 -1 1960s 1970s 1980s 1990s 30: Premium B & C 22: 3-R NG Upg 21: 3-R I Upg 20: Exe. Mais. 19: Exe. A prt. 12: 4-R A 11: 3- & 4-R A 08: 5-R I 07: 4-R NG 06: 3- & 4-R NG 05: 3-R NG 04: 2-R I 03: 3-R I 01: 1-R I 02: 2-R S -2 2000s Figure 8-23: Chart showing the indicative trendline of indoor environmental quality performance 184 In contrast to the other three indicative environmental performance trends, the indicative trend of service quality performance shows a clear improvement. The environmental performance scores are progressively higher over time with the peak performances belonging to the case studies built in the 1990s. These case studies perform well in terms of visual privacy and access to view, and quality of amenities and site development. In general, the driving force for the enhancement of the overall service quality over time is the sharp increase in the indicative trend of quality of amenities and site development, which is a logical response to the increase in resident aspiration and expectation of the living environment in the context of public housing. Ind ica tive tre nd line o f se rvice q ua lity (G B C sco re ) -0.2 -0.1 -0.2 0.8 0.8 0.3 0.1 0.5 1.3 0.8 0.2 -0.2 -0.2 1.3 1.2 0.2 0.6 0.2 0.2 0.1 27: Exe. -0.4 0.8 0.4 21: 3-R I Upg -0.3 0.7 22: 3-R NG Upg -0.4 03: 3-R I -0.2 02: 2-R S 0.3 28: Premium A & B 1.3 0.8 26: 4-R A & 5-R -1 1960s 1970s 1990s 29: Premium B 30: Premium B & C 25: 4-R A & 5-R 24: 4-R A & 5-R 23: 4-R A & 5-R 19: Exe. Aprt. 20: Exe. Mais. 18: Exe. Aprt. 16: 5-R I 17: Exe. Mais 15: 5-R A 14: HUDC Aprt. 12: 4-R A 1980s 13: HUDC Mais. 10: 5-R A 11: 3- & 4-R A 08: 5-R I 09: 4-R S 07: 4-R NG 06: 3- & 4-R NG 04: 2-R I 05: 3-R NG 01: 1-R I -2 2000s Figure 8-24: Chart showing the indicative trendline of service quality performance 8.8.2 Clarifying the assumptions and the result environmental performances A first glance into the indicative total environmental performance trend (Figure 8-20) appears to be alarming to public housing providers. This undeniably would create doubts and suspicions to the assessment method; as the trend shows that environmental performance of public housing design has been continuously declined, the best practice was dated back or decades earlier, and the recent housing development is the worst. The trend may also create scepticism and pessimistic thinking in the practice of environmental public housing development. 185 However, the actual situation is not as dreadful, because the assessment method was carried out in a particularly purposeful way to cater for the analysis of this research. The indicative trends, as constructed, not imply comparison among the case studies in terms of their total environmental performance at the same period of time, but rather in each case study's respective built periods. Case studies in earlier years are assessed with the often larger household size, less energy and water consumptions in compared with case studies in the later years. These are, however, the facts in the social evolution and trend as residents become more affluent and aspiration; which dictate and influence the outcome environmental performances issues of resource consumption and environmental loadings, and thus the total environmental performances of the case studies. In order to clarify the ' doubtfulness'caused by the above indicative total environmental performance trend, another assessment version is carried out for all the case studies and presented below. In this second version, the assessments are carried out for all case studies with the same current practice in terms of household sizes, energy and water consumptions. The second version of assessment results are summarised and illustrated in Figure 8-25, Figure 8-26 and Figure 8-27. In the second version of assessment, applying the same high energy and water consumption and small household size of current practice (in comparison to the earlier years) to all case studies, it is observed that resource consumption and environmental loading performances of the case studies from earlier year to later year showed a general increase. This is a reversed outcome in comparison to the first version of assessments. The case studies with lower performances in these two categories are those built in the earlier decades, rather than those built in the later decades. 186 0.6 -0.6 -0.1 -0.4 -0.4 1.2 14: HUDC Aprt. 0.4 15: 5-R A 0.4 0.7 17: Exe. Mais 0.5 18: Exe. Aprt. 19: Exe. Aprt. 0.8 20: Exe. Mais. 0.7 21: 3-R I Upg 0.5 22: 3-R NG Upg 0.4 0.1 24: 4-R A & 5-R -0.2 23: 4-R A & 5-R -0.2 29: Premium B 0.4 0.5 0.5 30: Premium B & C 0.3 27: Exe. 28: Premium A & B 0.1 26: 4-R A & 5-R 0.4 25: 4-R A & 5-R R e so urce co nsum p tio n p e rfo rm a nce (2 nd ve rsio n o f G B C sco re ) -0.4 -0.2 -0.2 -0.5 13: HUDC Mais. 16: 5-R I -0.8 12: 4-R A -0.2 11: 3- & 4-R A -0.8 10: 5-R A -1 0.1 29: Premium B 30: Premium B & C -0.4 -0.1 28: Premium A & B 0.4 27: Ex e. 08: 5-R I 09: 4-R S 2000s 26: 4-R A & 5-R -0.1 0.3 2000s 0.1 0.3 25: 4-R A & 5-R -2 0.9 0.2 24: 4-R A & 5-R -0.2 -0.3 23: 4-R A & 5-R -0.5 21: 3-R I Upg 22: 3-R NG Upg 06: 3- & 4-R NG 07: 4-R NG 1990s 0.7 20: Ex e. Mais . 04: 2-R I 05: 3-R NG 1980s 0.8 0.7 19: Ex e. A prt. 02: 2-R S 03: 3-R I 1970s 17: Ex e. Mais 18: Ex e. A prt. 01: 1-R I 1960s 1.4 0.8 0.5 15: 5-R A Figure 8-25: Chart showing resource consumption performance of case studies (as in the second assessment version) 0.1 -0.1 -0.1 14: HUDC A prt. E nvironm ental loadings perform ance (2nd version of GB C score) -0.5 13: HUDC Mais . 16: 5-R I 0.1 12: 4-R A -0.4 -0.3 -0.5 -0.4 11: 3- & 4-R A -1 10: 5-R A -0.5 08: 5-R I 09: 4-R S -1 -0.1 29: Premium B 30: Premium B & C 0.2 28: Premium A & B 0.2 27: Ex e. 07: 4-R NG 0.8 2000s 26: 4-R A & 5-R 06: 3- & 4-R NG -1 0.7 25: 4-R A & 5-R 05: 3-R NG 1990s 0.5 24: 4-R A & 5-R -2 0.6 22: 3-R NG Upg 23: 4-R A & 5-R 04: 2-R I 1980s 0.2 21: 3-R I Upg 02: 2-R S 03: 3-R I 1970s 0.4 20: Ex e. Mais . 01: 1-R I 1960s 0.4 1990s 19: Ex e. A pr t. Figure 8-26: Chart showing environmental loading performance of case studies (as in the second assessment version) 1.0 17: Ex e. Mais 18: Ex e. A pr t. To ta l p erfo rm a nce (2 nd versio n o f G B C sco re ) -0.1 14: HUDC A prt. 16: 5-R I 5.0 0.0 13: HUDC Mais . 15: 5-R A 4.0 0.1 12: 4-R A -0.4 1980s 11: 3- & 4-R A 0.3 09: 4-R S 3.0 0.0 08: 5-R I 10: 5-R A 2.0 1970s 07: 4-R NG 0.0 -0.1 05: 3-R NG 06: 3- & 4-R NG 0.0 -0.4 -0.2 -0.4 04: 2-R I 1.0 03: 3-R I 0.0 02: 2-R S -1.0 -2.0 1960s 187 Figure 8-27: Chart showing the total environmental performance of case studies (as in the second assessment version) 01: 1-R I As a result, the total environmental performance among the case studies in this second assessment version are different from the one constructed earlier in this chapter. In this second assessment, case studies built in the 1960s, not the ones built in year 2000 and beyond, have the lower total environmental performance. In summary, the indicative environmental performance trends, as constructed earlier in this chapter, encompass a potential of misinterpretation. The misinterpretation derives from that the indicative trends did not imply a comparison among the case studies in terms of their environmental performances at the same period of time. The indicative trends rather made comparison among the case studies in each case study's respective built periods. In order to clarify this confusion, a seco nd version of assessment has been carried out, with input data of household size, energy and water consumptions based on the current social context and practice of year 2000 and beyond (rather than based on the built-period context of each case study). The results show different performance scores for the case studies built before year 2000. The earlier indicative environmental performance trends are constructed in a purposeful way to facilitate the objectives of this research. They are, therefore, the primary data to be used for the research analyses in the subsequent chapters. 8.9 Conclusion This chapter has explained the selection of case studies in the construction of indicative environmental performance trends of public housing development since the 1960s. It has elaborated on the assessment methods of each environmental performance categories and criteria, and has outlined the assessment outcomes of the case studies. These outcomes have been presented in the form of indicative environmental performance trends – a compilation of all case studies'environmental performances – which will be the empirical data for the discussion in Part III. The chapter also clarified the result environmental performances of case studies against the assumptions made in the assessment process. 188 [...]... set of criteria (w1, w2, …, wn) from that matrix The following is a brief summary of the mathematical theory of the AHP, as reference to Saaty and Vargas (1991) and Harker (1989) The matrix of pair-wise comparisons A = (aij) can be established as follows: A1 A2 … An A1 a1 /a1 a1 /a2 … a1 /an A2 a2 /a1 a2 /a2 … a2 /an An an /a1 an /a2 … … an/an 149 ... Benchmarks are derived from calculation of the baseline housing block The calculation is based on estimates of average annual local rainfall, absorption capacity of site through permeable paving and landscaping (See 6.3.3.) All waste water in the housing block is discharged to municipal drainage system Central grey water treatment facility, rather than discrete on-site facility, is applied in Singapore. .. residential average energy consumption Figure is calculated from statistic information (Department of Statistic, 20 02) R .2. 1 Net area of land used for building and related development purposes Net area of land used for building and related development purposes 0 .2 m2 land per m2 net area in a total site area of 4 820 m2 Benchmarks are derived from calculation of the baseline housing block R .2. 2 Change in. .. preferable Making an analogy to environmental 148 performance of a building, there are certain causal factors in building design (e.g providing large openings) that leads to certain environmental performance (e.g good natural ventilation and poor indoor privacy) At this point, the actors must make a judgement to sway towards either natural ventilation or privacy The AHP allows the inclusion of both situations... multi-functional communal hall is provided S.5 .2 Quality of parking area development (to minimise the adverse affects of on-grade parking areas) Quality of parking area development Parking areas are in multi-storey carpark surrounded with some landscaping, and dedicated walkways lead from parking areas to a building entrance S.6 Impact on quality of service of site and adjacent properties To be assessed relative to... not assessable Q.3 Daylighting and Illumination Daylighting Q.3.1 Provision of daylighting in primary areas of all occupancies Q.3 .2 Potential glare in primary areas of all occupancies Not applicable Air movement in primary occupancies is under developing in GBC 20 00 Provision of daylighting in living and kitchen area 1.5% daylight factor Benchmark is calculated from the baseline housing block, based... mainstream studies are positioned against the Integrated Framework for Sustainable Housing Design and Discourse This has revealed some issues that have not been explored by existing literature for a comprehensive understanding of sustainable development of Singapore public housing This research, through using the setting of Singapore public housing development to critically review the practice of environmental. .. Through the setting of Singapore public housing, critical review of the practice of environmental performance from sustainable housing perspective in this research will explore the above issues and contribute some knowledge of Singapore public housing from sustainable housing perspective 128 6.5 Conclusion This chapter has briefly recaptured the evolution of Singapore public housing There have been... public housing in the three domains – socio-economics, housing design and environmental performance – has been reviewed and grouped into three mainstreams of study – interrelationship of housing policies and socio-economic factors, housing design and social aspects; as well as housing design and environmental performance After grasping with the overview issues related to Singapore public housing, the. .. housing design and their environmental performances In order to understand the sustainable development of Singapore public housing, the above topics in literature review are arranged in line with the structure of the Integrated Framework for Sustainable Housing Design and Discourse (Figure 6-6) Housing policy 6.3.1 Socioeconomics 6 .2 Housing design 6.3.3 Environmental Performance 6.3 .2 Figure 6-6: Diagram . understanding Singapore public housing in terms of sustainable development. Through the setting of Singapore public housing, critical review of the practice of environmental performance from sustainable. of sustainable development of Singapore public housing. 6 .2 The evolution of public housing development – a review 6 .2. 1 Public housing in the 1960s Emerging in the midst of acute housing. Building in Singapore (BEAM). Total Building Performance assesses 6 mandatory performance aspects of building, which are ‘spatial quality, thermal quality, acoustic quality, visual quality, indoor