The effect of coverings on heat transfer from a window to a room

The presence of a blind adjacent to a window, affects the natural convective and radiant heat transfer from the window to the room. As a result, the use of a shading device will change the heat transmission and solar heat gain through the window. A number of numerical and experimental studies of the effects of blinds on the heat transfer from a window have therefore been undertaken, with some of the main features of these studies being described here. In these studies, attention has been given to Venetian, vertical, and plane blinds, although the major attention has been given to Venetian blinds. Initial studies examined the effect of all three types of blinds on the natural convective heat transfer at an indoor glazing surface when there is no solar irradiance. Supporting experimental studies using mainly interferometry were then undertaken, particularly for the Venetian blind case. The numerical and experimental work was then extended to include the effects of solar radiation, in particular the effect of heat generation in the blind resulting from absorbed solar radiation. In addition to providing basic information on the effects of blinds on the heat transfer process, the studies, described here will assist in expanding available software for predicting window heat transfer to include the effect of window coverings and assist in the selection of energy-efficient window coverings.