The Energy Performance Assessments (EPA) Project is sponsored by the Energy Technology Support Unit on behalf of the Department of Energy. It aims to accelerate the uptake of low energy and passive solar design of buildings, through the use of field trials on occupied buildings. These field trials assess energy, cost and amenity issues in low energy and passive solar buildings. The methodology established involves preliminaries including a survey of the building; measured energy; modelled energy; reference energy; measured amenity; modelled cost; and reference cost. (author).