Influence of Air Leakage in Building’s Walls on Heat Transmission Loss through its Envelope

The energy consumption of a building is evaluated by neglecting the heat loss which can occur when the air passes through the envelope. However, recent studies showed that air leakage plays asignificant role by affecting the thermal performances of walls and the energy consumption. Moststudies have focused on the quantification of air leakage flows through the building shell, withoutaddressing the problem of the heat exchange between this airflow and the construction materials asthe air passes through the envelope. The standard way of calculating a building load considersconduction (or assimilated) losses independently of airflow energy losses.In this paper we present results from a parametric study conducted on two buildings: a single familydwelling and a school building In order to have a global view on air leakage impact on the overallheating load of a building. According to our calculations a significant part of energy load can beattributed to air leakage: till 8% for the single family dwelling and 12% for the school building.