The prediction of building air tightness is often discussed. Although I have my doubts about most prediction method, some researchers show good compliance with measurements. I also have written a very rough method for the dutch energy perrformance standard. The method I developed is taking into account:
- Year of construction
- Building type
- Construction type
- Quality of the execution during construction
- Envelope versus volume ratio
with this simple parameters one can find with a simple model a conservative estimate of the air tightness of buildings.
But my warning or message to anyone using prediction tools for air tightness of buildings is:
be very careful
because once we had a project with 100 dwellings from 10 architects. Each architect had designed a group of 10 equal dwellings. We measured the air tightness of one dwellings of each architect. Moreover, we measured the 10 dwellings of one architect. The result was that the variation between the 10 architect was about the same as the variation of 10 of the same dwellings from one architect!!!