Critical minimum acceptable window size: a study of window design and provision of a view

When working light is provided by permanent supplementary artificial lighting, the function of the window is modified. The main visual functions then become (a) the provision of a view, and (b) the provision of some modelling light to enhance the appearance of solid objects. This study was concerned to establish whether a critical minimum size of window could be assessed subjectively. It was found that a criterion could be recognised, and that this critical minimum size was governed more by the visual information provided by the view outside than by the amount of daylight or sunlight which penetrates the room, by the level of interior artificial lighting or by the viewing position in the room.