Modem applications for energy saving in buildings need to include dayl
ighting. Natural illumination will not only reduce the demand of elect
rical energy for fixtures but will also reduce the energy demand of ai
r conditioning during a hot period. Conventional approaches consider t
he natural illumination of architectural spaces by using a statically
sky lumination distribution, e.g. the standard overcast sky according
to the German DIN (DIN, 1983). This approach is not sufficient if ener
gy saving should be calculated since it does not take the fluctuating
sky lumination at the site of the building into account. This defect c
an be overcome by extend an existing illumination Simulation program t
hat computes only statically by a dynamic routine. (C) 1998 Published
by Elsevier Science Ltd. All rights reserved.