Global and diffuse horizontal illuminance data are analysed for Athens, Greece, for the period 1992-1997. It is shown in a graphical manner that horizontal illuminance (global and diffuse) is dependent upon the time of the day and the month of the year. The diagrams are categorized according to Perraudeau’s nebulosity index, which reflects the sky cover and the climate at a given area. The cumulative frequency distribution of the parameters under all-sky types are estimated and discussed. Some examples of sky-luminance distributions using appropriate software are given. The conclusions are of potential value to local architectural practice, installations of lighting, and in developing an energy-saving policy for the Athens region.
Interpreting the cumulative frequency distribution of Socio-Economic data
