The diffuse illuminance on work plane The daylighting application in Satel-Light allows you to use case studies to generate information on interior lighting levels, for the site you selected. This is the first time that it is so easy to take into account the influence of climate in daylighting. The diffuse horizontal illuminance at any of the 36 points on the work plane are computed every half hour, by combining the averaged sky luminances in 13 zones of the sky and 13 directional daylight factors (DDFs) describing the contribution of each zone to the diffuse horizontal illuminance at this point. The computation is summarized below (DDFs are expressed in % and luminances in kcd/m2). Directional daylight factors depend on the point of the room, on the sky zone and on the case study. They have been pre-computed using the Genelux-Web light simulation program. The solar penetration on work plane Information on the penetration of sunlight on the work plane is also available in Satel-Light. This information is based on the following procedure: every half hour, we test whether there is sunshine (i.e whether the direct normal irradiance exceeds 120 W/m2). If this is the case, the solar elevation and the solar azimuth are used to check which point of the work plane is reached by the sun rays. Then, for the whole period of time, statistics are produced to show how often one or all of the points on the work plane are reached by sunlight.