The purpose of this research was to measure the solar heat gain coefficients of three types of thick, high-mass glazing block systems under two distinct solar angle conditions. The glazing blocks used in this research project were actual glass blocks. At the time this work was completed, its purpose was to provide information for use in the National Fenestration Rating Council’s efforts to create their draft standard titled “Standard Test Method for Measuring the Solar Heat Gain Coefficient of Fenestration Systems Using Calorimeter Hot Box Methods.” This research was intended to provide insight into the potential problems related to the measurement of the SHGCs of high-mass window fenestration products using solar calorimeters.

The primary conclusion is the requirement to track the sun while testing high-mass-type fenestration products. Although a nontracking system will reach values similar to those of the tracking system, the duration of time is too short to be considered steady state.