Ventilation and the leakage characteristics of dwellings

Abstract

As fabric heat losses decrease with improved thermal insulation, ventilation heat losses, as a fraction of the total, become relatively more important. Thus, further effective energy savings may best be achieved by reducing energy losses associated with excessive ventilation. However, a means of measuring ventilation levels, or the magnitude of the air leakage paths through which ventilation takes place, is required to ensure that sealing of some openings does not result in unacceptably low ventilation rates and the accompanying risks of condensation, mould and poor indoor air quality. The fan-pressurisation technique does not measure ventilation rate directly, but air leakage data may be used for comparisons between houses and to predict ventilation rates which would occur under natural conditions. Air leakage data for a sample of 32 traditionally constructed Scottish dwellings are presented and discussed. The mean air leakage rate in these dwellings was found to be 60% higher than that found in a sample of 100 dwellings throughout the UK. It is concluded that there is considerable scope for reducing air leakage rates, and therefore ventilation heat loss, in many Scottish dwellings.