The quality and quantity of natural light in an interior depend on two main factors; the design of the exterior environment and the design of the interior environment. In this study, the necessity of daylighting on building facades was emphasised to get enough amount of daylighting in inner spaces. The decision chart for diffuse daylight in existing buildings was presented after investigating some methods that are used in the design of external environment. Investigation was made seperately for newly developed areas, existing buildings and adjoining development areas and some examples were given with necessary definitions and reference values.