In recent years, there has been increasing concern over energy use because of its cost, the continuing depletion of world fuel resources, and the environmental impact of CO2 emissions from combustion of fossil fuels. It has been estimated that buildings account for approximately 50 per cent of primary fuel consumption in the UK. Of this, commercial or public buildings account for over half. Furthermore, health issues in the workplace have lately received great attention, the internal environment of buildings being at the forefront with widespread reporting of "sick building syndrome". This document provides a means of assessing the energy and environmental performance of buildings, and comparing this with design. A test procedure involving a number of steps set out as an algorithmic flow diagram with accompanying notes is presented here. This enables the user, faced with the task of providing a performance test of a building, to plan a series of operations to achieve this goal. The procedure defines key aspects of building performance, and provides guidance on evaluating them.