Review of the sky temperature and solar decomposition, and their impact on thermal modeling

Performing accurate hourly building energy modeling requires presence of reliable boundary conditions. The required data for energy simulation model entries are exterior air temperature, exterior air relative humidity, solar radiation, sky temperature, wind velocity and cloud cover. Unfortunately, most available measured solar energy data is in the form of global horizontal radiation. Moreover, measured night sky temperature is normally not available. Proper energy modeling of a full building requires to have accurate solar radiation intensity on angled building envelope assemblies as well as precise sky temperature data available. In this study, among several available models, three hourly horizontal global solar radiation decomposition models, four hourly diffuse radiation on inclined surface models, and five sky temperature estimation models are studied for Vancouver climate. For solar radiation validation perspective, 2013 one-year measured total solar radiation on a south-east oriented wall located at BCIT Burnaby Campus is compared with the results from selected solar models. For both solar radiation and sky temperature models, impact of using different models on transient heat transfer results of light-weight and mass-type walls (two walls) are reviewed. Results reveal high impact of both solar and sky temperature models on hourly heat transfer simulation results.