An important input of ray tracing models used in architecture to simulate the luminance distribution in a building is the sky luminance distribution. This parameter is not routinely acquired, even if it is recommended by the CIE. A modelisation of the sky vault luminance distribution based on a radiative transfer models is not feasible with the actual input parameters. A attempt was conducted in Geneva to correlate the asymmetry of a real sky distribution with 41x41 pixels satellite images, but without significant results. Existing symmetric sky luminance distribution models are evaluated in the present work, and recommendations are given for the use of them.