This investigation of the window-opening data from extensive field surveys in UK office buildings demonstrates: (1) how people control the indoor environment by opening windows; (2) the cooling potential of opening windows; and (3) the use of an ‘adaptive algorithm’ for predicting window-opening behaviour for thermal simulation in ESP-r. It was found that when the window was open the mean indoor and outdoor temperatures were higher than when closed, but it was shown that nonetheless there was a useful cooling effect from opening a window. The adaptive algorithm for window-opening behaviour was then used in thermal simulation studies for some typical office designs. The thermal simulation results were in general agreement with the findings of the field surveys. The adaptive algorithm is shown to provide insights not available using non adaptive simulation methods and can assist in achieving more comfortable, lower energy buildings while avoiding overheating.

The urgent need to reduce anthropogenic greenhouse gas (GHG) emissions in a bid to meet increasingly stringent GHG targets has focused the attention of scientists on the built environment. The reason is that nearly 50% of all the energy in the developed world is consumed in buildings and it is here that the easiest savings can be made. Although the theoretical trend in building regulations is to favour lower carbon buildings, in reality new buildings have typically become more energy profligate year after year. Much of this results from increased mechanization, poorer building fabric and design, and the resource consumption patterns. Modern thermal comfort standards are partly responsible for increased levels of energy consumption in buildings as well as for encouraging unhealthier, less comfortable buildings because they drive the designers towards higher use of air-conditioning. A first step towards the radical overhauling of our approach to the artificial conditioning of buildings is to revise these st...