Monday, October 22, 2012

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

Conclusions and Recommendations


Design Issues


As a conclusion, there are some design issues discovered in traditional Malay houses and social housing (Table 42). According to research, materials that are used in Malay houses are more practical and reliable for releasing heat readily, compared to high thermal capacity materials such as bricks and concrete in social housing. These high thermal materials store heat and cause uncomfortably high temperatures at night.

The unplanned kampong environment does not block the wind; thus the entire neighbourhood receives a good quality of fresh air. Externally, in modern housing large blocks and long terraces create barriers and air pockets, while internally, the complicated wall arrangements in modern housing block air movement, which leads to an uncomfortable thermal condition.

In a traditional Malay house, full-length openings are located at body level, while in modern housing the openings are smaller and only concentrate on the upper part of the body. Therefore, the cross ventilation process often fails in modern housing. Overhangs are important in opening components because they can provide shade for the walls from sun radiation, glare and rainfall. This key element is always neglected in modern housing.

For religious reasons, the orientation of a traditional Malay house normally faces Mecca or an east-to-west direction. This orientation, by coincidence, can reduce the external wall that faces direct sunlight. However, in modern housing, this orientation is not emphasized for profit motives. Moreover, the internal space arrangement in a traditional Malay house uses a front-to-back order where the serambi is the first area, followed by the rumah ibu and dapur. This arrangement preserves the privacy level of a Malay family and contributes to neighbourhood enhancement.


The results of the analysis of Malay houses and People’s Housing Project (PHP 2000) show that the performance of air temperature and relative humidity in both cases were not significantly different. However, for internal and external air ventilation, the traditional Malay houses recorded 1450.3 l/s (1.45m/s) compared to just only 31.7 l/s (0.03m/s) for PHP 2000. The massive amount of air ventilation in Malay houses contributes to a better performance of the house thermally and economically.

The theoretical model has been developed and tested. The model has been improved according to the architectural and construction issues found in an actual PHP 2000. One of the major improvements is the proportionate rule of layout unit. Instead of a long and narrow layout, the theoretical model has a longer and wider layout where the external wall area is longer than PHP 2000; this promotes massive airflow in, out and across the house through the opening components.

Using the results obtained in part 7 and 8, a standard called Air House has been defined. This standard is totally focused on natural ventilation strategies, in which air is designed to flow across the house compound. Meanwhile, in Passivhaus, the design is more about airtightness and isolation of heat within the house compound. The establishment of Air House could perhaps be a new beginning for Malaysian architecture and its tropical region.

The hot temperature and high humidity climate in Malaysia encourages the use of an air conditioning system as the primary option to cool the house. Nowadays, this is the standard practice in Malaysia. An effort should be made to rectify this situation. The theoretical model that has been developed proves that there is a possible way to achieve the right thermal comfort by using passive methods in social housing. Therefore, this study answers the problem posed at the beginning of the study.


Recommendations of Building Regulations in Malaysia

Upon completion of the study, it can be deduced that there is a huge gap between the traditional approach and modern housing. One of the reasons for this situation is the inappropriate regulations and standards being used in Malaysia. Therefore, some improvements and revisions should be made in order to meet the current challenges, as some of the regulations are not compatible with Malaysia’s climate and culture (see Table 43).

In clauses 32, 33, 34 and 35 of UBBL part III (space, light and ventilation), open spaces must be provided in residential building compounds. However, the categories listed are only related to buildings abutting a street, a back lane and a detached building; there is no category relating to linked units abutting a corridor in a multi-storey building. According to the research findings, a common space in front of the main entrance is an important element in building a good, responsible society. Therefore, in theoretical model (TM), foyer space is provided to serve as interaction space as well as storage area. Thus, an improvement that can be compatible with local culture and the basic needs of the people should be made.

Clause 39 (1) states that residential buildings shall be provided with natural lighting and natural ventilation. The openings area is not less than 10% of floor area. For an example that follows the minimum requirement, a living/dining area in TM that has 19.6 square metres will have an area of window opening of less than 2.0 square meters. Based on the research findings, this percentage is too small for an opening to allow air movement. As TM has been proven to provide good air movement, clause 39 (1) should be revised to a new and more suitable percentage of opening area that is compatible with Malaysia’s climate.


In order to achieve thermal comfort through air movement, a large opening at the external and internal wall should be made. Therefore, 15% to 20% of external openings are required on an external wall for achieving suitable amount of air movement. Moreover, an opening at a high level of wall should be placed to allow ventilation and air change processes.

The window openings are suggested to be placed at body level range and must be 15% to 20% of a room’s external wall. For internal partitions, fixed louvers could be placed on the top part of the partition to allow air transfer from room to room.

Moreover, in clause 42 (2), the minimum kitchen area in UBBL is 4.5 square metres and the minimum width is 1.5 metres. This measurement is still small and leads to insufficient space area. Therefore, the kitchen area should be revised to be at least 8.0 square metres and 2.0 metres minimum in width.

Finally, in clause 44 (1), the minimum height of a living room is 2.5 metres, while a kitchen is 2.25 metres. These heights are considered low and less efficient to promote air movement; thus, the minimum of 3.5 metres, as in TM’s design, should be used in this clause.





The Air House concept that focuses on natural ventilation in residential buildings has proven it can reduce 86% of carbon emission and 74.3% of energy consumption compared to standard practice. The Air House concept has brought sustainable design in Malaysia to a new level of achievement; therefore, it should be explored and expanded in greater detail in the future. Among other study areas in Air House that can be further defined are:

• The appropriateness of use of lightweight building materials in the tropics;
• Percentage proportion of openings in accordance with the building height;
• Wind catcher strategies in Air House design to promote cross ventilation; and
• Strategies in preventing sound pollution in Air House design.

Thermal comfort is one of the basic needs. However, in urban areas, thermal comfort becomes more crucial as houses are constructed in multi-level format with compact design. The concept of Air House could perhaps provide a new dimension in the design of comfortable and sustainable housing in the future.

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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The Establishment of 'Air House' Standard in Tropical Countries : Part 8

The Establishment of ‘Air House’ Standard in Malaysia


From Passivhaus to ‘Air House’


In Europe, Passivhaus (Passive House) standard has been established to achieve the most suitable thermal comfort condition in a building during winter and summer. According to Audenaert, et al. (2008), ‘passive house is a type of low-energy building; design is oriented to make maximum exploitation of passive technologies, assuring a comfortable indoor climate during summer and winter without needing any conventional heating or cooling system’. The passive house concept focuses on airtight insulation that can prevent air infiltration and retain heat in the building. Its aim is to achieve 10 times less heat energy than the same standard designed building (Feist, et al., 2005). Table 33 shows the Passivhaus standard that has to be achieved in order to claim Passivhaus certification in the United Kingdom.

Table 34 shows the common construction criteria for Passivhaus standard, which involves a high level of insulation on the walls, floors and roofs; a continuous air tightness layer on the window frames; high thermal mass materials and thermal bridge-free construction; and a mechanical ventilation system with a high efficiency heat recovery. The Passivhaus standard can help to reduce 80% of carbon reductions as a legislative target for the UK Government (Passivhaus Trust, 2012).


Inspired by the Passivhaus concept, there is a need for a design standard to be established in Malaysia (or perhaps in the tropical region) for designing a building that can achieve a balanced thermal comfort by using natural resources such as solar and wind without dependence on mechanical equipment.

In a tropical country, air temperature, relative humidity and air movement are all vital factors in achieving a good level of comfort. With high temperatures day and night, and high humidity throughout the year, a building design that can channel the heat out is very important. Air movement through large opening areas is the key element in achieving thermal comfort in Malaysia.

The air movement is suggested to be between 0.15 to 5.4 m/s, which can be defined as a standard. Moreover, low thermal mass materials (lightweight) are the best option for this kind of climate condition as they do not retain heat and release it readily. The house that has met this standard could be called ‘Air House’.

Initial Concept of ‘Air House’

In order to reduce carbon emission and energy consumption of a building, especially in social housing, the use of natural resources such as solar radiation and wind is particularly valuable. A wise use of natural resources has been adopted in the design of a Malay house with balanced temperatures day and night, preferable humidity and large volumes of air movement in and out.

Thus, the theoretical model that has been developed and tested has achieved the Air House standard equivalent to a traditional Malay house. This Air House standard produces cross ventilation by allowing a suitable amount of air movement inside the building through some percentage of external opening area. This standard should be defined, and the thermal comfort results from the Malay houses and TM cases in Tables 35, 36, 37, 38 and 39 are the most suitable and valid parameters to be used as the Air House standard.




The main findings from the results are:

• The mean air temperature in Malay houses and TM ranges from 25.2 0C to 27.2 0C (Table 35). This range can be considered the best air temperature in a naturally ventilated building in Malaysia.

• The minimum relative humidity in Malay houses and TM ranges from 30% to 60% (Table 36). This range is achievable and therefore can be considered the preferred humidity range in a naturally ventilated building.

• The mean internal ventilation in Malay houses and TM cases (except the dapur and serambi) ranges from 0.15 to 0.4 m/s (150.0 to 400.0 l/s) (Table 37). Meanwhile, the external ventilation in Malay houses and TM (except the dapur) ranges from 0.30 to 1.45 m/s (300.0 to 1450.0 l/s) (Table 38). Thus, the preferred range of air ventilation in a naturally ventilated building is 0.30 to 1.50 m/s.

• The external opening area in a Malay house is 15% to 20% (table 39), while in TM, the opening areas on the walls facing outside (open space) is 25% and the wall facing inside (corridor) is about 50%. These percentages could be the best configuration of opening percentage in a naturally ventilated building.

• The best carbon emission for a naturally ventilated building is 2571 kgC02/year, and the energy consumption should not be more than 5.1963 MWh/year.

The findings listed above are the initial parameters than can be used as the first Air House standard in Malaysia.


‘Air House’ Standard for Naturally Ventilated Building in Malaysia

Based on all the results defined in Malay houses and theoretical models, the proposed Air House design standard is listed in Table 40. The air temperature ranges from 250C to 270C. The relative humidity for ‘Air House’ is 30% to 60%. Meanwhile, the air movement is between 0.30 to 1.50 m/s. The total energy consumption for Air House standard is less than 5.0 MWh/year and less than 2500 kgC02/year for carbon emission.




Table 41 shows the design parameters for a naturally ventilated building in Malaysia. 15% to 25% of an opening area is recommended for an external wall that faces an open space, while for a wall covered by shade or facing another block, 25% to 50% of an opening area is recommended. As higher altitude provides higher velocity, the units located on the eleventh floor and above should have a smaller opening area than units on the first to tenth floors. Furthermore, to promote air movement and cross ventilation, the four components of opening in Air House that should be implemented are bottom louvers, windows, top louvers and high louvers. The proportionate rule of these openings is 2x : 2x : 1x : 1x relatively, as shown in Figure 65.

Moreover, the unit plan layout should be in proportion of 1.5x for walls parallel to the corridor, and 1x for walls perpendicular to the corridor (Figure 65). To provide shade from sun radiation and rainfall, the minimum overhang recommended is 0.6 metres, while to promote better air circulation around the building, breaks between units are recommended. In terms of material selection, Air House standard uses prefabricated, lightweight and low thermal mass materials for the walls, floor and roof components.



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. 




The Establishment of 'Air House' Standard in Tropical Countries : Part 7

Performance Comparison of Theoretical Model (TM) and PHP 2000


Indoor Air Temperature

Referring to Table 28, the mean temperatures for both cases in TM are slightly higher than PHP 2000 by 0.3 0C. Moreover, the maximum temperatures in TM are higher than PHP 2000 with a difference of 3.7 0C, and the minimum air temperature in TM and PHP 2000 differ by 1.8 0C.

Fondriest Environmental (2012) suggests that when gas molecules move quickly, air temperature will increase and affect other weather parameters such as the rate of evaporation, relative humidity, wind speed and direction. The indoor air temperature is proportional to outside air temperature; therefore, large external openings and louvers that allow air movement into internal spaces contribute to the high temperatures in TM, especially during the day. However, these large openings help to decrease the temperature in TM significantly at night, as suggested by Saini (1970). The best level of temperature is 25.5 0C to 28.0 0C (Hassan & Ramli, 2010). Therefore, the mean and minimum air temperatures in TM are categorized as preferred temperatures.



Relative Humidity

Table 29 displays the results on relative humidity in PHP 2000 and TM. The mean relative humidity in the kitchen area for both cases in TM is slightly lower than that in PHP 2000. The maximum relative humidity results in TM’s cases are 4.8% higher than the PHP 2000 cases. Meanwhile, for minimum relative humidity, the cases in PHP 2000 recorded higher humidity than TM’s cases.

The difference in minimum relative humidity for TM and PHP 2000 is 14.7%. The recommended level of indoor humidity in Malaysia is in the range of 30% to 60%; thus, only results for minimum temperature in all cases are within the recommended level.

The high humidity can only affect the comfort level in a room where the air movement is too low (Saini, 1970). Therefore, the crucial variable that contributes to a good thermal comfort in a building in a tropical climate is air movement.





Internal and External Ventilation

Table 30 shows the internal ventilation results in PHP 2000 and TM. The mean internal ventilation for cases in TM showed an increase compared to cases in PHP 2000, except the kitchen area in case 5. However, there was a significant increase in TM cases for maximum internal ventilation, which ranges from 720.3 l/s to 1273.7 l/s, compared to just 293.2 l/s to 413.3 l/s in PHP 2000.

As has been suggested by Hassan and Ramli (2010), the Beaufort scale has set the best levels of performance for the wind speed range from 1600.0 to 5400.0 m/s (1.6 to 5.4 m/s). Thus, the internal ventilation in TM has better results than PHP 2000.





Based on Table 31, the TM cases had recorded numerous results with the highest mean of 544.7 l/s, compared to the results in the PHP 2000 cases, which were less than 40.0 l/s. In TM, both cases recorded high air movement for maximum external ventilation ranging from 2160.1 l/s to 5331.5 l/s (2.1 to 5.3 m/s), compared to lower results in PHP 2000.

From the results, TM has achieved the better level of wind speed. Therefore, the results have proved that TM has a better thermal comfort than PHP 2000. Figure 61 shows the days of minimum and maximum internal ventilation for the first floor level in TM, where cross ventilation has functioned properly through its openings.




Figure 62 shows the days of minimum and maximum external ventilation in TM for the tenth floor unit, where the amount of air movement increases compared to first floor unit. The increment of air movement for the tenth floor unit is 36% more than the first floor unit; each floor receives an increase of 3.6% of air movement. As the tenth floor unit receives the maximum level of preferred air movement of 5.4 m/s, the opening areas for the eleventh floor and above should be reduced gradually to maintain the preferred level of air movement.

From the tables and figures discussed, it can be concluded that the longitudinal plan layout that has long external walls receives a higher volume of air; the volume increases as the altitude increases. The placement of the windows and louvers opposite one another in TM cases produces air changes inside the building equal to that of a Malay house.




Carbon Emission and Energy Consumption

Table 32 shows that numerous decreases of energy consumption and carbon emission happened in TM. TM’s carbon emission has reduced by 86%, and its energy consumption decreased by 74.3% compared to PHP 2000 (air conditioned). It can be deduced that an air conditioning system is the biggest culprit for producing high-energy usage in residential buildings in Malaysia. The results proved that the natural ventilation concept used in the building has a tremendous influence on economical and environmental effects. This natural ventilation method can contribute to massive energy savings for the country as well. These results show that TM’s design is practical, environmental friendly and economical.



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.  





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.  









Friday, October 19, 2012

The Establishment of 'Air House' Standard in Tropical Countries : Part 5


Case Studies Analysis

The Selection of the Case Studies

Three case studies have been selected, two of which are traditional Malay houses, and the other a social house from the People’s Housing Project Scheme (PHP 2000). The Malay houses selected are the house of Datuk Baginda Tan Mas Mohar and the house of Andak Endah. The houses are located in two different areas; the house of Datuk Baginda Tan Mas Mohar in the Negeri Sembilan state (southern region) and the house of Andak Endah in Perak state (northern region).

The house of Datuk Baginda Tan Mas Mohar, built in 1850, and the house of Andak Endah, built in 1920, have been chosen as typology houses and represent two different forms. The house of Datuk Baginda Tan Mas Mohar has a basic twelve column structure, while Andak Endah has an expanded twelve-column structure. Social housing in Malaysia has been standardized, so using the People’s Housing Project (PHP) as the third case study is quite reasonable.

Table 15 shows the total external wall area and its opening areas percentage. The Datuk Baginda Tan Mas Mohar house has 16.5% opening areas and the house of Andak Endah has 17.9% opening areas. Meanwhile, PHP 2000 has only 8.9% opening areas. The size and location of opening areas are two key factors that can allow air to enter the building sufficiently. The two cases of Malay houses have larger opening areas compared to PHP 2000.



Simulation’s Design Settings


The selection of the 6.4 version of the Integrated Environmental Solutions Software (also known as (IES ) is due to its suitability towards the aims of the study, which is to simulate air temperature, relative humidity and air flow rate. For natural ventilation, MacroFlo, integrated into the IES simulation, is used to simulate airflow driven by wind pressure and buoyancy forces through elements such as windows, doors and openings. The simulation of MacroFlo runs from within Apache, which also simulates the indoor air temperature and relative humidity based on the ASHRAE design weather database. Meanwhile, MicroFlo uses a Computational Fluid Dynamic (CFD) to measure fluid flow and heat transfer processes around building spaces, which include the effects of climate (IES, 2012).

In this study, the simulation’s location database is Kuala Lumpur/Subang weather with the latitude 30 12’ North and longitude 1010 55’ East. The sea level height is 8 metres with the mean dry-bulb temperature 36.4 0C and wet-bulb temperature 16.1 0C. No HVAC system is applied, while east-west orientation is used in all simulation models. The openings of all samples assigned as window/door side hung with opening angle is 900, and opening hours range from 08:00 am to 10:00 pm. All the external walls are categorized as exposed walls without any obstacles.

According to Saini (1970), air temperature, relative humidity and air movement are the elements of climate which affect the comfort and well-being of the people. These factors also have complex inter-relationships between them, and, to a degree, each affects the other. Therefore, in this study, these three elements will be measured in detail, as well as carbon emission and energy consumption.

Table 19 shows the building materials assigned to both Malay houses and PHP 2000 in IES. The right building materials are crucial to achieve accurate readings in simulation. However, several regional materials such as an attap roof (a thatched roof made from palm leaves), a bamboo thatched wall, and a gap-timber-floor are not available in the IES material database. Therefore, the closest materials shown in Table 19 were chosen.



Results and Findings

Indoor Air Temperature


Air temperature is the mean temperature of the air in the room (Mohammadi, et al., 2010). Based on Table 20, the mean air temperatures in the Malay house cases have lower results than PHP 2000 by a 1.7 0C margin. These results show that the large opening area at the perimeter walls and roof in Malay houses work well in promoting natural ventilation.

Moreover, the maximum air temperatures in PHP 2000 are lower than the Malay house cases by a 2.0 0C margin. These results show that the high thermal mass materials used in PHP 2000 have succeeded in reducing the internal temperatures of the house during the day. Meanwhile, the minimum air temperatures in the Malay house cases are lower than PHP 2000 by a 1.5 0C margin. It concludes that the lightweight materials used in a Malay house can release heat readily and cool the house at night.



Relative Humidity

Relative humidity is the water vapour pressure of the air expressed as a percentage of the saturation vapour pressure (Mohammadi, et al., 2010). According to Table 21, the mean relative humidity in PHP 2000 is lower than the Malay house cases by 5.9%. In addition, the maximum relative humidity in the Malay house cases is higher than PHP 2000 by 7.1%, and the minimum relative humidity in PHP 2000 is higher than the Malay houses by 4.3%.

Wolkoff and Kjaergaard (2007) suggest that the recommended level of indoor humidity in Malaysia should be in the range of 30% to 60%. Therefore, the relative humidity of the traditional Malay houses and PHP 2000 are not at the recommended level.

From the results, it can be deduced that the Malay houses have a high level of humidity and a low temperature, while PHP 2000 has the opposite. According to Saini (1970), as in physiological effects (body temperature and sweat production), the low temperature and high humidity conditions are the same as those with high temperature and low humidity. Therefore, the air temperature and relative humidity in both cases have less of an impact on thermal condition.




Internal and External Ventilation

MacroFlo external ventilation is the volume flow that enters through a MacroFlo opening, and MacroFlo internal ventilation is the volume flow leaving through a MacroFlo opening (Mohammadi, et al., 2010).

From the MacroFlo simulation’s results (Table 22 and Table 23), the traditional Malay houses recorded a higher internal and external airflow ventilation compared to both PHP 2000 units. The most significant value of external ventilation was recorded in the Andak Endah house with 1450.3 l/s (1.45m/s), compared to PHP 2000 with only 31.7 l/s (0.03m/s). The differences in terms of air movement in both Malay house cases are tremendous. The air movements leaving and entering the house are significantly higher than PHP 2000. Therefore, the maximum internal and external ventilation in the Malay houses achieved a better rate of wind speed of 1600.0 to 5400.0 l/s (1.6 to 5.4 m/s).

These findings are vital in this study because the movement of air, for instance, reduces the effects of humidity and air temperature (Saini, 1970). Therefore, a traditional Malay house that has high air movement is proven to have better thermal comfort than PHP 2000.



Carbon Emission and Energy Consumption


Thermal comfort theory is used as a guidance for the assembly of fabric and plants that will determine the environmental conditioning system (Fisk, 1981). Fish (1981) added that assembly can lead to many alternative uses for patterns and energy consumption. From the thermal comfort results discussed before, the high heat storage materials that contribute to high temperatures in PHP 2000 at night are one of the reasons air conditioning systems have been installed. This is the quickest way to reduce heat in the house but it also produces high-energy consumption and carbon emission.

Table 24 shows the comparison of carbon emission and energy consumption for two different PHP 2000s. One unit uses an air conditioning system, the other is fully naturally ventilated. Both carbon emission and energy consumption for the PHP 2000 with an air conditioning system are higher than the PHP 2000 that uses natural ventilation. The carbon emission and energy consumption for the air-conditioned house is 67% and 66% higher than the naturally-ventilated house. Even though an air conditioning system leads to an enormous increase in carbon emission and energy consumption, it is still the top choice for Malaysians in addressing thermal discomfort at home.





Summaries and Key Points

The selection of the case studies is based on house forms. The Andak Endah house has a basic form while the Tan Mas Mohar house has an expanded form. The location of the house that influences the stilt height is also one of the selection criteria. Therefore, these two houses are best served as typologies for their respective form group and location. Meanwhile, social housing has a typical standard design which can be constructed anywhere in this country. So, PHP 2000 is the right representative for social housing development in Malaysia.

From the simulation’s results, it can be deduced that the air temperatures in PHP 2000 and Malay houses show no significant difference within each other. The mean air temperatures obtained are within the comfort levels mentioned in part 4. However the relative humidity results are higher than their suggested level (part 4). Even though the relative humidity is high, there is only a small change in the air temperature. A change from 25 to 75% of relative humidity is predicted to move the temperature by only 1 0C (Fisk, 1981).

The crucial finding obtained from the simulation is the air movement. Air movement in this scenario is very important because it can encourage heat loss through the evaporation process. Low air movement does little to generate a body’s heat loss. Furthermore, Fisk (1981) suggested that air movement of about 150.0 l/s (0.15 m/s) or greater tends to increase air temperature and a body’s heat loss. In conclusion, a traditional Malay house that has high air ventilation movement in and out has the better shelter and can provide more comfort to the human body than PHP 2000.

On the other hand, the carbon emission and energy consumption for the naturally ventilated PHP 2000 are far lower than the PHP 2000 that uses an air conditioning system. The carbon emission and energy consumption levels for a naturally ventilated house are much lower than an air-conditioned house. The huge gaps here show that it is worth encouraging people to use natural ventilation methods rather than an air conditioning system. Malay houses, for instance, can best describe the concept of a naturally ventilated house. Therefore, some elements, such as the size of openings and their placement, can be forwarded to a detailed level.

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.