The energy consumption of non-domestic buildings varies over a wide range, even for buildings of similar-use types as illustrated in Figure 1.1. A well-designed daylit and naturally ventilated office building such as the BRE Low Energy Office (building no. 92 on the graph), with efficient and well-controlled plant, will have an annual energy cost less than £3.0/m2yr. On the other hand, an air-conditioned, deep-plan, overglazed building, with poor services design and control, could cost more than £45.00/m2yr.