This is the characteristic of a closed window to allow air to be filtered in the case of a pressure difference between inside and outside. The classification is evaluated by measuring the air leakage resulting from the applied pressures that anticipate four classes of performance (1,2,3,4).
The water resistance of a building casing can be assessed by the “blower-door- test,” which measures the rate of air exchange due to infiltrations. Running this test during the construction works, one can adopt any corrective measures against heat loss, thus preventing damage to the structural elements and associated clean-up costs.
Why an air tight house?
A good air tightness is not only a sign of the quality of work carried out, it is also a feature which reduces the loss of heat and therefore energy costs; it improves living comfort, prevents the formation of condensation in the building elements, negate the effect of thermal bridges, prevents the infiltration of radon from the basement and improves the efficiency of the ventilation system.
• A perfect insulation of the building is useless if winter heat can dissipate through unchecked leaks or cracks.
• A perfect protection of the building from sunlight is useless if the hot air in summer can penetrate through cracks or gaps left unchecked.