Improving solar data in CIBSE climate files – Survey of measuring networks and test on daylight simulation

This paper investigates the influence of solar radiation models on Climate-Based Daylight Modelling (CBDM) evaluations. The solar radiation model currently implemented in CIBSE files is compared with high-accuracy reference data, and a new approach based on measured data and separation models is proposed. An in-depth survey of solar radiation data currently available for British locations is also presented. The analysis on solar radiation data and models showed that the current climate files under-estimate all irradiance components, whereas a combination of Met Office data and the Skartveit separation model can drastically improve irradiance estimates. The use of this improved model to derive irradiance values led to a significant improvement in the reliability of CBDM results as well.