I am calculating the air infiltration rates through cracks and openings in a 10 storey building in Mauritius - and it's quite a daunting task. Improper assumptions could make the results misleading. Is there any empirical study and published external air infiltration rates through cracks and normal openings of the building constructed before the new Part L Regulations? I am trying to assess what could be the air infiltration rate due to wind and stack effect and which should contribute to a load on the AC system? There are currently no regulations regarding air tightness in Mauritius, and it could be assumed that the building will be constructed without any particular attention to air tightness.
Actual measurement of air infiltration rates is the only accurate way of determining the air infiltration load on any AC system. However, at the design stage this is not possible. Estimating the air infiltration rate through the building envelope can be difficult. BRE has an air leakage prediction program which has shown good correlation with actual measurements, though you still need to convert the air leakage index or permeability of the building into air infiltration rate. This can be done but again accuracy is the key factor.
You suggest that buildings in Mauritius are built without air tightness in mind so the air infiltration could be significant. Any information on air leakage figures may be similar for UK and Mauritius, but that would have to be established.
Source
Building Sustainable Design
