Simulation and testing of curtain wall/ sloped glazing systems

U-factor losses in commercial fenestration can have a significant effect on building loads, yet there is little information on the performance of these products. With this in mind, ASHRAE TC 4.5, Fenestration, sponsored a research project involving test and computational analysis of commercial fenestration systems. The objectives of the project were to evaluate the thermal performance (U-factors) of commonly used commercial glazed roof and wall assemblies; to obtain a better fundamental understanding of the heat transfer processes that occur in these specialty fenestration products; to develop general correlations for laminar natural convection flow in complex glazing cavities; to develop a methodology for evaluating complex fenestration products, suitable for inclusion in ASHRAE proposed standard 142P; and to generate U-factors for common commercial fenestration products, suitable for inclusion in the ASHRA E Handbook —Fundamentals. This paper describes actual and computer-simulated hot box testing of a curtain wall/sloped glazing specimen for various conditions and slopes and provides guidelines for modeling comme rcial glazed wall system s based on the validated results.