Performance of a new scanning sky simulator

A new type of sky simulator has been developed,using a scanning process, to build up the complete sky hemisphere, starting from a sixth of the whole hemisphere. This novel apparatus possesses numerous advantages when compared to other simulators. It can reproduce any sky luminance distribution, from theoretical CIE models to statistical skies, i.e. International Daylight Monitoring Programme (IDMP) measurements. A detailed analysis of experimental errors has shown, that the relative average discrepancy between the simulated skies and their corresponding models, varies from 1.5% to 3%. This device allows quantitative (daylight factors) and qualitative analysis (video imaging) of daylighting system performance. The operation, performance and experimental results of this sky simulator are described in this paper.