Reducing air infiltration losses in naturally ventilated industrial buildings.

The UK factory stock is predominantly naturally ventilated. Measurements performed in this class of building have indicated that air infiltration rates in factories are usually excessive in relation to occupants' requirements for health and safety, resulting in an energy penalty. As part of a project to investigate construction options for energy efficient industrial buildings, three factories of different cladding construction types were designed and then built at Aberarnan, South Wales. One of the primary aims of the project was to reduce air infiltration losses and increase air tightness. Attention has been paid to design details in order to achieve these aims. The construction process was observed in order to monitor site practice and workmanship. Tracer gas tests (primarily constant concentration) tests and air leakage (fan pressurisation) tests have been performed to determine the air infiltration rate and air leakage performance of the factories. A thermographic survey was used to assist the identification of the major air leakage sites. The results have shown that air infiltration rates have been reduced by the order of 40% for the three 'conventional' cladding constructions. Air leakage rates measured at 50 Pa are the lowest achieved in this class of building in the UK, based on published data. The major site for air leakage was found to be the eaves detail.