Describes sunlight in and around buildings, the means for its assessment, the criteria by which its adequacy may be judged and environmental consequences arising from its presence. Solar heat gain accompanying the admission of direct sunlight is considered. The information supplied and the principles set out apply to occupied space in all types of building in greater or lesser degree but, in considering levels at which the designer should aim, attention has been directed mainly to residential buildings, offices and schools with some comments on hospital wards.