Close encounters.

Discusses the advantages of reducing air infiltration in industrial buildings in terms of energy conservation. States that heat loss due to infiltration is often underestimated or ignored as it is difficult to measure. Concentrates ondoorways as a major source of infiltration, and shows that the type of door used needs to match the requirements of the entrance, such as type and size of vehicle passing etc. Decribes a range of doors suitable for different conditions.