The objective of the subtask is to derive a model to evaluate the luminance distribution of the sky vault on the basis of Meteosat data. This information is a key element in the field of building energy saving, it is the basis of indoor daylight calculation. Evaluation programs like Genelux (LASH-ENTPE) need this sky luminance distribution to perform their calculations. Sky luminance distribution models have been developed in the last years on the basis of horizontal diffuse illuminance. Their precision depends on the input data and these models cannot take into account the statistical cloud distribution in the sky vault. Perez et al. tried to superpose a statistical cloud distribution on their symmetrical model, but this was done on a unique set of data and a particular site. The model was not tested on other data (due to the lack of clean and complete sky luminance distribution database) and therefore cannot be used in any site by now without a question mark on the results.