Presents the result of a study supported by the DETR under the Partners in Technology scheme. Provides guidelines on the factors required to achieve successful natural ventilation in offices in summer by the use of openable windows. 

A combination of physical and computer modelling was used to examine the limiting conditions for natural ventilation through one external facade to be effective in providing a comfortable and healthy indoor environment on a still, warm summer day. 

Presents the design guidelines and summarises the research and findings from which the guidelines were compiled.