Development of solar heat gain factors database using meteorological data

In tropical and subtropical regions, solar heat gain via fenestration, particularly on vertical surfaces, plays an important role in determining the thermal performance of a building. For sizing air-conditioning equipment, maximum solar heat gain factors (SHGFs) are used for estimating the design peak load. Recently, the SHGF data representing the prevailing weather conditions have become essential and more practical for part load performance designs and daylighting schemes evaluation. In the absence of measured solar radiation data for the determination of SHGFs, meteorological radiation models may be used. This paper presents the validation of SHGFs prediction models based on sunshine hours and horizontal solar data. Statistical assessments for the models have shown that using sunshine hours to predict the hourly SHGFs may not be appropriate for dynamic building simulation studies. For the average SHGFs computation, all models present acceptable results. In determining the SHGFs for horizontal and vertical surfaces at the peak and other significant levels, all prediction models perform better than the ASHRAE clear sky approach, particularly at high significant levels. This finding also provides information for the estimation of total air-conditioning plant capacity at both the peak load operation and the multiple equipment sizing under part load condition.