Study Of Daylighting Metrics Based On Luminance

The light environment is a very important part of the building environment.Daylight can keep people healthy. The daylighting performance evaluation is a veryimportant part of the daylight research area.Nowadays daylighting metrics is based on the illuminance. The daylight factor isthe most widely used metric which presents the minimum value of the daylightingunder the worst weather conditions throughout the year. This static metric can notreflect the dynamic changes over time and therefore dynamic daylighting metrics isneeded. International research on the dynamic lighting metrics has becomeincreasingly active and a variety of dynamic metrics has appeared. However theexisting dynamic daylighting metrics still has its limitations because only consideringthe level of illumination and basing on the absolute value.To limit the shortage of the illuminance metrics this paper presented newdaylighting metrics based on luminance which called usefull luminance and usefulllumunance ratio. In order to verify the applicability of the luminance metrics ancommon office sited in Tianjin was selected to carry out the evaluation experiments.Found In this progress typical sky illumination and luminance data was colected, theluminance value within the field of view was calculated by the SM system and theusefull luminance and usefull lumunance was applied to assess the daylightingenvironment and compared with the traditional illuminance metrics. Results showedthat the luminance metrics were more suitable than traditional illumination metrics toevaluate the people’s subjective visual experience.