No abstract

Daylight performance metrics are moving away from the traditional daylight factor and average illuminance to more climatic-based metrics such as Daylight Autonomy (DA) and Useful Daylight Index (UDI). These metrics offer a better measure of the daylight performance throughout the year and incorporate the varying weather conditions and as such are dubbed climatic-based metrics. However, in hot climates where the ratio of direct to diffuse is highest, achieving these metrics may result in overheating the spaces. Achieving acceptable climatic-based metrics for the space may result in unacceptable heat gains. The Day light Autonomy and the Useful Daylight Index do not account for the total amount of lux-hours achieved throughout the year. The solution thus far has been to run coupled-energy and daylight simulations and in order to assess the effect of achieving certain climatic-based metrics on the heat gain and thermal performance of the space. In this paper a new metric is proposed that takes into account the total amount of lux-hours achieved throughout the year and the irradiation for different time step into a single measure. Details about the measure and sample test cases are presented.