Thursday, October 18, 2012

The Establishment of 'Air House' Standard in Tropical Countries : Part 4

Malaysia’s Thermal Comfort, Regulations and Housing Issues

Thermal Comfort Conditions in Malaysia

Indoor thermal comfort is crucial for buildings in the tropics, where the majority of social housing in Malaysia is naturally ventilated and very few houses are able to use an air-conditioning system (Harahap, et al., 2011). Table 9 shows seven studies of thermal comfort in Malaysia.

For the purposes of this study, the latest study conducted by Hassan and Ramli (2010) has been selected as a basis of thermal comfort measurement. Table 10 shows the range of air temperature, which at the best performance level is 25.5 0C to 28.0 0C (Hassan & Ramli, 2010). Moreover, the authors suggest that, based on a study by Wolkoff and Kjaergaard (2007), the recommended level of indoor humidity in Malaysia is in the range of 30% to 60%, as shown in Table 11. Meanwhile, Table 12 shows the Beaufort scale of wind speed. The best levels of wind speed performance range from 1.6 to 5.4 m/s. The thermal comfort measurement that has been selected will be used as a comparison with the results obtained in chapters 4 and 5.

Saini (1970) added that the ‘loss of heat by convection and radiation can only take place when the air and surroundings are at less than body temperature. Loss by evaporation depends upon the relative humidity of the surrounding air and the rate of air movement over the body’.

A large volume of air ventilation is important to maintain good thermal conditions in any naturally ventilated building. According to Saini (1970), the human body will continually adjust and adapt to its surroundings’ temperature and maintain the temperature equilibrium of 36.8 0C. In tropical areas, the temperature happens to be extreme and this causes heat stroke or intense fatigue for the tissue. Therefore, to lose heat to its surrounding is vital for the human body. There are three ways in which the human body can lose heat to its surroundings, which are by convection, evaporation and radiation (Saini, 1970).

Regulations and Recommendations

There are a few guidelines that can be referred to in designing a building in Malaysia. The most common is Uniform Building By Laws (UBBL) and Malaysian Standard 1525 (MS1525). Meanwhile, the Green Building Index (GBI), established since 2009, is the most advanced benchmark for designing an environmentally responsive building in Malaysia, and focuses on the efficiency of resource use for energy, water and materials (Green Building Index, 2012). There are six criteria in the GBI rating system: energy efficiency, indoor environmental quality, sustainable site planning and management, materials and resources, water efficiency, and innovation.

The use of GBI is encouraged in all new construction or base building refurbishment, or as construction and procurement phases of buildings to assess and improve their environmental attributes (GBI, 2012). For example, in an indoor environmental quality (EQ) assessment, such projects are encouraged to achieve certain criteria. These include maintaining a minimum indoor air quality performance to enhance indoor air quality in buildings; meeting the minimum requirements of ventilation rates in the local building code; and providing cross ventilation for all public and circulation spaces. Generally, GBI (2010) has suggested that to achieve cross ventilation, some openings should be made on both sides of the room in addition to the low and high openings for stack ventilation. However, the opening size area and the specific indoor design conditions for naturally ventilated space have not been defined yet. The purpose of this study is to define indoor design conditions for a space without an air-conditioning system.

The local building code referred to is Malaysian Standard 1525 (MS1525), which lists thermal comfort conditions for an indoor space designed with an airconditioning system but not a naturally ventilated indoor space. According to Harahap, et al. (2011), the UBBL does not specify any thermal comfort conditions, while MS1525, which is the code of practice on energy efficiency and use of renewable energy for non-residential buildings, does list specific thermal comfort conditions for indoor spaces designed with an air-conditioning system, as shown in Table 13.

Meanwhile, GBI refers to the same standard in MS1525 as its thermal comfort benchmark. Even though a standard for thermal comfort in an indoor air-conditioned space has been set up, it does not reflect the real situation of Malaysia’s comfort level, especially for naturally ventilated buildings. This standard concentrates on mechanical equipment that the majority of the low-income population in Malaysia is unable to afford. Moreover, the air conditioning system also releases large carbon emission and contributes to high-energy consumption.

Established in 1974 under the Street, Drainage & Building Act, Uniform Building By-Laws (UBBL) has become the main reference for building designers in Malaysia. One of the objectives of UBBL is to ‘set standardised building regulations for the whole of Malaysia and applicable to all local authorities and building professionals’ (Mohamad Said, 2011).

However, the guideline is not totally designed according to the circumstances and climate of Malaysia. Mohamad Said (2011) stated that ‘the Uniform Building By- Laws was based on the existing Kuala Lumpur and Singapore legislations and recommendations from the Building Research Station, United Kingdom’.

In 2010, the Housing and Local Government Ministry reviewed the Uniform Building By-Laws to promote green technologies in buildings and to create a sustainable living environment in Malaysia (The Star, 2010). This initiative shows that sustainable living has become important and that the UBBL regulations in Malaysia should meet this current demand. This concept is in line with the initiative from the Malaysian government to reduce carbon emission by as much as 40% compared with 2005 levels (The Star, 2010).

Social Housing Issues in Malaysia

Malaysia is one of the developing countries experiencing a highly rapid urban growth. This situation has led to large migration from rural to urban areas, and resulted in the existence of slums and squatter areas. Social housing such as the People’s Housing Project Scheme (PHP) is one of the initiatives by the government to solve this problem. As the demand is very high, hundreds of thousands of PHP schemes have been built since 1998. However, the PHP design has received a lot of criticism for its insufficient space size and location.

Amongst the architectural issues raised is the lack of a storage area (figure 29). Therefore, the majority of residents placed their goods in front of their house; this affects the efficiency of a corridor as a safety route. The main door unit located abutting the corridor without any recess reduces the opportunity of neighbourhood interaction (figure 29). Meanwhile, the small size and deep location of the kitchen and yard restricts its functions. The orientation of unit layout that has a minimum external wall area minimizes openings and air movement (figure 29). The internal layout of the PHP 2000 that has complicated partitions reduces cross ventilation. Furthermore, openings such as aluminium casement windows without top louvers does not allow air movement to enter the indoor space.

On the other hand, the insufficient location of the bathroom and bedroom doors reduces the privacy level of residents (figure 29). In the PHP design, the toilet and bathroom areas are separated, meaning a restriction in air and people movement in these spaces.

Furthermore, heavyweight materials with a high heat storage capacity are not suitable to a warm-humid climate like Malaysia. These materials take a considerable time to heat, then once heated take a long time to cool down again (Saini, 1970). Thus, lightweight materials that have a low heat storage capacity should be observed and replaced by conventional materials. In conjunction with that, prefabricated construction methods could be implemented in PHP 2000 to make it flexible in terms of internal space layout.

Construction Issues

Materially, brick wall and post and beam concrete are the most common construction methods for social housing in Malaysia, largely due to these materials being cheap and easily available. Brick construction has a low u-value of 1.96 wm2 0C, though it has an eight-hour time lag, which has an adverse effect on the internal environment, especially at night (Hanafi, 1994).

Saini (1970) suggested that in a warm-humid region, heavyweight construction is at a disadvantage since the cooling process at night is so slow that the indoor temperature is kept too high for a comfortable sleep. Therefore, materials with a high heat storage capacity, such as brick, concrete and stone, have no advantage in Malaysia’s climate.

In addition, the residents of PHP flats agreed that the adjustable louvered windows are better for air movement compared with aluminium casement windows (Goh & Ahmad, 2011).

Recently, the shortage of construction labour means prefabricated panels and frames have been used widely. In 1988 the Malaysian Government began efforts to persuade the construction industry in Malaysia to engage with a more systematic approach, such as an Industrialized Building System (IBS), in building construction (Abd. Rahman & Omar, 2006). Besides the aims to reduce the dependency on foreign labour, an IBS construction method can also contribute to reducing construction periods and pollution of the environment.

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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