Characterization of daylight quality by computation of performance indicators and rendering with Radiance
Marie-Claude Dubois & François Cantin (speaker)
ABSTRACT
Powerful tools
like Radiance allow an accurate prediction of daylight conditions and can be
used at a design stage to study different architectural configurations and
decide which design will yield the best daylight or light conditions. However,
the decision between two or three different designs is not always
straightforward since there is no generally accepted model of daylight or light quality. In this paper, an evaluation of
daylight quality is presented based on the computation of a large set of
performance indicators and on a subjective evaluation of the scale of shadow in
a set of renderings. The indicators considered are: the daylight glare index,
the luminance ratios, the luminance difference index, the
vertical-to-horizontal illuminance, the absolute luminances, the horizontal
illuminance, the size, location and intensity of sunlight patches and the
cylindrical illuminance. This paper will present the methodology used in
Radiance to efficiently compute these performance indicators. It will also show
that it is possible to fully characterize daylighting by a careful examination
of these indicators for a large number of times and skies, which will help to
support the design process.