Monday, October 22, 2012

The Establishment of 'Air House' Standard in Tropical Countries : Part 6

Towards A New Typology of Social Housing Design

Design Comparison of Theoretical Model (TM) and PHP 2000

A theoretical model (TM) has been developed as an initiator towards sustainable social housing in Malaysia. The model design is a reflection of the design issues found in PHP 2000 that were discussed in part 5. The issues of space sizes, internal circulation, cross ventilation and numbers of openings in PHP 2000 have been taken into consideration. PHP 2000 and TM have the same overall area of 650 square feet, which is equivalent to 60.38 square metres (JPN, 2006) (Table 25). The differences between these two are the size of the spaces. In TM the living/dining area is smaller than in PHP 2000 to allow foyer space in front of the main entrance. This space has a similar position to the serambi in a Malay house to promote interaction between neighbourhoods. The other improvement in TM is a larger yard space than in PHP 2000, as shown in Figure 49. This is because in PHP 2000, the yard design is too small and located too far from the exposed area, which leads to insufficient space for a clothes-drying area. On the other hand, the separation of the toilet and bathroom in PHP 2000 means the toilet size becomes too small and uncomfortable. In TM, both facilities are located in the same space; thus it creates better movement of the occupant and air.

Because the humidity is high, air movement is crucial to help perspiration to evaporate (Bureau of Meteorology, 2012). Hence, TM has been designed with windows opposite each other, a narrow floor plan and ventilation openings such as top and bottom louvers to allow air movement.

As discussed in part 5, a traditional Malay house was chosen as a reference; the importance of the rumah ibu is to function as the main space, and the dapur as a secondary space. As shown in Figure 50, the common hierarchy of a traditional Malay house, front-to-back order, was used in the TM design. The serambi is used as the first area, followed by the rumah ibu. The selang acts as a link to the dapur and ends with the pelantar as a wet space. This arrangement maintains the lifestyle and culture of the Malay people.

Architectural Improvements

Several architectural improvements have been implemented in the TM design, which involve the external and internal design forms. The external form of PHP 2000 is extending the length and width to about 7.3 metres by 9.5 metres. Meanwhile, the TM is elongated sideways to 10 metres by 7.5 metres of length and width. This orientation makes the external wall of the TM larger than the PHP 2000, increasing its external opening areas. Table 26 shows the comparison of external wall and opening areas in both the PHP 2000 and TM. In TM, the external wall area is larger than PHP 2000, which is over double the PHP 2000 percentage. Figure 51 shows the location of internal and external openings such as windows, doors and louvers in the PHP 2000 and TM. TM’s openings are more uniform and perpendicular than PHP 2000. This arrangement stabilizes air movement that flows in and out through perpendicular openings. Meanwhile, the large overhangs on top of the windows provide shade and reduce glare and direct sun radiation.

Figure 52 shows the air movement in the PHP 2000 and TM designs. The complicated wall arrangements in PHP 2000 reduce the cross ventilation that flows from the front to rear fa├žade. In TM, cross ventilation is achieved with a parallel arrangement of windows as well as the placement of high louvers on the internal walls, as shown in Figure 53. Furthermore, overhangs are placed on top of the windows to provide protection from sunlight and rainfall. The width of the overhang is 600mm.

Window design in a traditional Malay house is divided into three operable sections, which are top, middle and bottom. As shown in Figure 54, TM has 3.5 metre-high walls, and its external walls are divided into three sections. The sections are top louvers, windows and bottom louvers. In a Malay house design, some openings on the gable ends are placed to allow air movement. Thus, in TM, the same concept is translated through the placement of internal and external high louvers.

In PHP 2000, the location of the kitchen area is in the middle of the house with just a small window for ventilation. Thus, during cooking activities, smoke will fill the house space. In TM, the kitchen area has many openings on its perpendicular sides that provide proper cross ventilation. Moreover, the yard area in PHP 2000 is located 5 metres from open space, compared to just 3 metres in TM. This way, the yard area in TM has a better function for clothes-drying.

In traditional Malay culture, the privacy of family members at home is fundamental. Therefore, public space (living) and private space (bedroom) should be separated. Nevertheless, the location of the bathroom must be strategic and preserve the privacy of residents. In PHP 2000, the location of the bedroom doors is right next to the living area, which reduces the privacy of residents. The improvement made in TM is the location of the bathroom, which is situated near to the bedrooms and living space, as shown in Figure 55.

Figure 56, below, shows the typical floor plan of PHP 2000 that consists of 20 units per floor. The yellow area on the plan shows the continuous corridors that link the house units to the fire staircases. The width of the corridor is about 1.45 metres, and the unit’s entrance doors are located along the corridor without any recess. One of the problems with the PHP 2000 design is residents having to use corridors for storage. This has affected the function of these corridors as fire escape routes.

As shown in Figure 57, TM’s planned layout has been improved with the allocation of a foyer as a storage area and a common area for residents to interact with neighbours. To enhance cross ventilation and air movement throughout the building, breaks between the units are allocated. The 2 metre breaks can also improve natural lighting to the corridor and foyer spaces.

Construction Improvements

In a hot-humid climate, a lightweight structure performs better as it cools down rapidly (Saini, 1970: 25). Furthermore, ‘materials with heat-storage capacity such as bricks and concrete have little benefit’ (Bureau of Meteorology, 2012). Therefore, a few changes on construction methods and building materials have been implemented for the theoretical model (Table 27).

In TM, lightweight materials such as a gypsum board with insulation is used for the external wall. Meanwhile, for the internal wall, plasterboard with insulation is the replacement for the conventional single brick wall. In a hot-humid climate, a thin insulation is preferable to bulk insulation, which is not desirable because it prevents the house cooling down at night (Bureau of Meteorology, 2012).

TM applies a prefabrication concept in its construction methods, where six columns form a unit, as shown in Figure 58. Moreover, the wall, window and louver panels are installed after the structures are erected, as shown in Figure 59. There is no internal column placed, thus the internal design is more flexible. This method provides some advantages; it can reduce the cost, construction period and number of workers at the same time.

In traditional Malay culture, the expansion of the house is determined by family size. The basic spaces in a traditional Malay house are the serambi, rumah ibu and dapur, where the number of bedrooms is provided according to the need. Therefore, this concept has been used in TM, as shown in Figure 60. Prefabricated wall construction in TM help to realize the concept, in which bedroom 2 and bedroom 3 can be assembled and dismantled.

In conclusion, the TM design that has been applied with architectural and construction improvements has now become one of the new typologies for social housing in Malaysia. Therefore, the changes applied in TM should be tested and analyzed to assess their suitability. The next step in this research is pursuing the analysis of TM in IES software. All the settings and simulation variables mentioned in chapter 4 will be used in order to provide a fair comparison.

Researched and written by Mohd Firrdhaus Mohd Sahabuddin; co-founder of 'Air House' and this article was a part of his dissertation which titled 'Traditional Values and Their Adaptation in Social Housing Design: Towards A New Typology and Establishment of ‘Air House’ Standard in Malaysia' for MSc. Advanced Sustainable Design in The University of Edinburgh. Copyright 2012.  

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