The Air Leakage in Refrigerated Vans Project was initiated by the Department of Energy to assess the impact of air leakage on fuel consumption of highway transport refrigeration equipment. The project, conducted from September of 1977 to December of 1978 collected air leakage data on refrigerated trailers, containers and truck bodies. A Prototype Air Leakage Test Set was developed, designed and constructed to take measurements, and a total of 92 representative vehicles were examined. The results of the study indicate that air leakage causes a 25% increase in the average refrigeration load. However, the majority of transport refrigeration units are equipped with control systems that require the power to be supplied continuously, so that the potential reduction in fuel consumption that can be expected by reduced air leakage is limited. Alternative control techniques and power sources for the control and operation of refrigeration unit components other than the compressor could reduce fuel consumption by approximately 60%.