Parametric definition of the daylight climate

Solar radiation and sunlight are the universal and free sources of renewable energy available everywhere and the survival of life and health as well as the conditions of environmental comfort and prosperity are dependent on their effective utilisation. Several parameters are used nowadays to characterise the sunlight and skylight conditions and their connection with the solar radiation climate. A complex concept linking the sky luminance patterns with the resulting skylight, that is, diffuse illuminance levels as well as usually coexisting sunlight illuminance is needed to express the exact definition of possible real cases either measured or predicted in a set of relevant parameters. Evaluation of measured data gathered by current IDMP (International Daylight Measurement Programme) stations presents also problems of parametrisation necessary for their study and general formulation of prediction and mutual comparison. This contribution tries to show various problems and solutions linking the radiation and daylight climate specification with the new set of sky types proposed for the CIE standardisation. (C) 2001 Elsevier Science Ltd. All rights reserved.