The level of comfort inside buildings is highly related to daylight availability, which is associated with solar access, irradiation on windows as well as solar rights. These mentioned variables are frequently calculated using similar methods. For the graphic study of these variables, mathematical projections are used which provide a geometric view of the analytical results. However, the existing projections are not suitable for calculating and representing sky vault luminance. In this paper we present a synthetic projection developed specifically for vertical windows in order to study and determine the main variables associated with solar exposure and natural lighting according to the International Commission on Illumination (CIE) standard overcast sky model recognized in the ISO standard. The proposed projection of the sky vault visible from a window provides insight on the problems related to natural lighting, shading and solar access, while aiding in solar access decision making. (C) 2013 Elsevier B.V. All rights reserved.