This part of ISO 12567 specifies a method to measure the thermal transmittance of a door or window system. It is applicable to all effects of frames, sashes, shutters, blinds, screens, panels, door leaves and fittings. It is not applicable to — edge effects occurring outside the perimeter of the specimen, — energy transfer due to solar radiation on the specimen, — effects of air leakage through the specimen, and — roof windows and projecting products, where the external face projects beyond the cold side roof surface. NOTE For roof windows and projecting units, see the procedure given in ISO 12567-2. Annex A gives methods for the calculation of environmental temperatures.