Argues that heat losses and ingress of cold air through factory doors are best reduced by the use of air locks and air curtains. Derives equations defining heat losses through unprotected doors. Illustrates air balance of an industrial shed. Diagrammatically illustrates in a graph relation of heat losses to size of entrance. Treats methods and effectiveness of reducing heat losses by air curtains and air locks respectively. Recommends unheated air locks except for circumstances dictating use of air curtains.
Expresses air infiltration rate measured using tracer gas in 2 similar town houses in terms of wind speed, wind direction, indoor-outdoor temperature difference, average rate of boiler firing and fraction of time that doors are open. Method yielded reproducible rates of air infiltration within 0.1 air exchanges per hour in any single one-week run once outside temperature, wind speed and wind direction were allowed for. States results partly reveal set of physical principles determining house air exchange rates which are so far poorly understood.