Air Tight Buildings to Save Energy?
It is unfortunate that building design in temperate climates is assumed to work in tropical zones! The irony of the issue is that the very idea of transferring temperate climate technology to tropical zones simply defies common sense but is sold by "the experts"!
Why is this not as it seems? Simply because the weather conditions differ so much between these zones! In temperate climates, an air-tight building makes sense because heating a room is difficult if there is a constant leakage of cold air into the building. Furthermore the idea is to keep the building warmer in winter.
This short article below will explain briefly why Air-Tight buildings are not so great in a correctly designed building in Malaysia !
Consider this design concept.....
1. An office room is to be air-conditioned.
2. There is a cooling system with a small exhaust at the toilets
3. Fresh air is allowed in for occupants and to counter the exhaust volume - the design,if done correctly, will create a positive pressure room because the fresh intake should be higher in volume compared to the exhaust - i.e. air is pushed out from the room.
Thus making the building air tight to prevent air from entering is not necessary UNLESS.....
The building is designed to be negative pressure - i.e. air from outside is forced into the room! This can occur if CO2 controls are put in place because the building will swing from positive pressure to negative pressure depending on how the controls are set. Controls become complicated when we try to make something simple to become "high tech". Sometimes SIMPLICITY works better and is easier to maintain.
Of course preventing air-conditioned air from escaping is good but the volume lost through this can be minimized by correct balance between fresh air intake and the exhaust system. By correct balance, infiltration into the room will be neglible because the room is positive pressured and wind speeds in most areas is generally low.
Again cost effectiveness versus "state-of-the-art" design!
Only if the design does not allow fresh air into the room will there be high infiltration volume of outside air through the building gaps. The end result is that due to air-tightness and lack of fresh air intake a potential IAQ issue in the building will be brewing!
An air tight office building is expensive to construct and it will make good sense to conduct a full cost-benefit analysis before proceeding. However, certain applications such as specific hospital rooms, special cleanrooms may require airtight construction.