2.0 FACTORS THAT AFFECT INDOOR AIR QUALITY

Types of houses, When was it built

The rate of ventilation in a house is calculated based on the number of openings (eg. doors, windows, etc.) that were installed in the house; which means the more openings, the more ventilation. Houses built in the past few decades were built “tighter” as to save energy and cost. A “tighter” house means the houses were built in such a way so that it is harder to “breathe” – almost none or less ventilation. Therefore, it would be logical to say that the more energy efficient a home is, the bigger chance the air inside that home is unhealthy.

In olden days, houses were built “loose” so that they could “breathe”. Take the olden days shop houses as example; they were built with internal courtyards. Cross ventilation designs were also designed to maximize ventilation, to cool the home in the hot weather. Internal courtyard invites natural air to come in homes; while cross ventilation helps circulates the air. The concept of cross ventilation is very straightforward actually: picture a room with openings on the opposite of each other. The cool air from outside enters the room through a opening, and in return, forces warm air in that room out from another opening. This encourages the circulation of air, which results in cooler interior.

But during these days if we were to build our houses more loose, will we be spending extra money on cooling electricity bills; because air leakage can lead to higher bills? Many of the modern Malaysian houses installed air-conditioning in their homes. Therefore, these homes must be built “tightly” or closed to avoid air leakage. Will air ventilation be lesser in the “tightly built” homes? Also, it is common sense that higher places have higher ventilation rates. But does the statement apply to apartments and condominiums, which are built higher than terrace houses?

Research cases were done to verify the theories stated above. Below are the studies and research of ventilation of 4 houses, aided by ASHRAE 62.1 application. Nonetheless, a few research were done on existing modern Malaysian houses (with/without air-conditioner turned on) to determine whether the ventilation is sufficient.     

Research Case no.1: TWO-AND-A-HALF STOREY TERRACE RESIDENTIAL HOUSE 

The first type of house studied is a typical two-and-a-half storey terrace, with total area of approximately 218sqM; also built with cross ventilation (note the opening from main entrance and the opening from the backyard; which is directly opposite each other). The ASHRAE 62.1 application shows that the critical area is the storeroom, very likely because it has no other openings except one door but it is kept closed at all times. The storeroom in this house is used to store old newspapers, old magazines, old books and so on. Although there is not much dust, the air is stagnant and musty smelling. This is probably due to the opening crack of the door which lets in rainwater during the heavy rain, and the newspapers get socked with rainwater. Besides the storeroom, the study room 2 is also lack of ventilation. It is located in the innermost corner of the house where the wind entering from the main entrance and backdoor will not be able to reach.

Overall, the house is quite ventilated, due to the presence of cross-ventilation. The main entrance (sliding doors opening with 1.5M), the backyard door and also the window openings from the master-bedroom allows cool air in the house and at the same time, forcing out warm air from inside the house.

Research Case no.2: SINGLE-STOREY TERRACE RESIDENTIAL HOUSE 

The second research on residential house ventilation is a single-storey terrace with total area of approximately 100sqM, and a total of 3 persons is living in the home.

With reference from the floor plan sketch above, wind from outside enters through the main entrance (sliding doors), windows in the master-bedroom and windows in the kitchen. The hatched areas in red (bedroom 1, bedroom 2 and study room) represent the areas with insufficient ventilation. One will feel the stuffiness once step foot inside the three rooms, due to lack of air circulation. Although the study room doors were kept open at all times, wind entering from the main entrance and the backdoor in kitchen is still unable to reach into the study room. ASHRAE 62.1 application does not label the dining room as critical zone but in actual, it feels warm to sit in the dining room, which indicates the sliding door opening (which measures about 0.9 meters) in the main entrance, is not sufficient for more wind to enter.

Research Case no.3: APARTMENT UNIT     

An apartment unit, approximately 150 square meters with 4 persons living in is the next research case. The spaces inside this apartment are a living room, a kitchen, 2 bedrooms and a washroom. Despite the window opening in the living room, the family living inside this apartment complains that the spaces inside the house are quite warm. The only explanation is perhaps there are no other openings that are sufficient to let the warm air out from the spaces. Even though there is a door (main entrance), opposite the door is another unit which blocks the wind outside from entering the living room through the main entrance. ASHRAE 62.1 application results show that the bedroom beside the kitchen has insufficient ventilation. There are no extra openings in the bedroom besides the door, and outside air from windows in living room could not enter this space.

Research Case no.3: CONDOMINIUM UNIT     

The last research case is a 200 square meter condominium unit, with only 2 people residing. The situation is almost the same as research case number 3; the outside wind is only able to enter the interior through the living room windows and the master bedroom windows. Although the living room in this research case quite airy compared to the living room in research case 3; there are two spaces that are labeled “critical” – the closet and the bedroom. There are no other openings for both the rooms except the doors which is kept closed at all times.