"The BRE advise that the following features cannot currently be properly represented by SBEM (and it's associated interfaces) · Night ventilation strategy · Ventilation with enhanced thermal coupling to structure · Demand-controlled ventilation · Automatic blind control · Variable speed pumping (for systems other than central heating using water) · Light transfer between highly glazed internal spaces such as atria or lightwells. Where these features occur, careful consideration should be given to the influence of the features on the overall energy usage of the building. If their influence is great, calculation tools other than SBEM may need to be considered to improve accuracy. A good understanding of the particular building and the principals involved should be attained before making this decision.