SE-99-12-4 -- Comparison of the Thermal Performance of an Exhaust-Air Window and a Supply-Air Window PDF

A computer program is developed to simulate the performance of triple-glazed supply- and exhaust-air windows using an hourly weather file for the city of Ottawa. The monthly net heat gains of the two designs are found to be nearly the same. The conduction heat transfer is found to contribute to a net monthly heat loss for every month of the year. This heat loss is always lower in the case of the exhaust-air window, and the difference in the conduction heat losses of the two window designs is the highest when the outdoor temperature is lowest. The solar heat gain is found to be higher in the case of the supply-air window. The difference in the solar heat gains of the two windows increases as the incident solar radiation increases. As far as thermal comfort is concerned, the exhaust-based design is always found to be superior to the supply-based design. The former window is associated with inner pane temperatures that are always closer to room temperature regardless of the season.

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