Impact of Building Airtightness on Heat Generator and Heat Emission Equipment Sizing

Cracks in building fabric lead to air infiltration due to wind and buoyancy driven forces. In the heating season, the cold air entering the building needs to be heated up to room temperature, thus leading to an energy demand. Conventionally, the measured infiltration rate at 50 Pa (expressed as n50 or q50) is recalculated into an average infiltration flow rate (yearly based) using leak infiltration ratio’s (LIR) ranging from 0.033 to 0.1, the origin of these values being sometimes unclear.