Development of a universal model for predicting hourly solar radiation---Application: Evaluation of an optimal daylighting controller

In this research work, a series of review and comparative analyses of several solar radiation/illuminance models has been carried out. A universal model has been developed and validated to predict hourly solar radiation for any site in the world. The validation of the universal solar model has utilized 139 primary and secondary stations and has indicated over 98% prediction accuracy on monthly basis and up to 93% accuracy in predicting hourly solar radiation levels. The universal solar model has been utilized to generate IWEC2 files for over 2,500 cities worldwide for building energy simulation analysis. Moreover, the universal solar model has been applied and tested to improve the prediction of hourly illuminance levels.;As an application of this universal solar model, an optimal daylighting controller has been developed and evaluated against conventional daylighting controls. The proposed optimal daylighting controller does not require photosensors to be placed inside and/or even outside buildings. The universal solar model would provide any needed data for illuminance levels to optimally control indoor lighting systems. The optimal controller defines the settings for various individual lighting fixtures and/or lighting circuits to minimize lighting energy use while maintaining acceptable visual comfort. A comparative analysis against conventional EnergyPlus daylight controllers shows that on average 20% more light energy savings can be achieved.