Effectiveness of External Window Attachments Based on Daylight Utilization and Cooling Load Reduction for Small Office Buildings in Hot Humid Climates

摘要

This study explored the effectiveness ofselected external shading devices and glazingtreatments used to minimize the total annual energyconsumption in small office buildings in hot humidclimates. The external shading devices included apermanent horizontal overhang and a light shelf.The selected types of glazing included clear,reflective, tinted, low-emissivity coating, andheat-mirror glass.One concern about using external windowattachments is that while reducing the solar heatgains, they also reduce the amount of the daylightneeded to supplement interior lighting. Therefore theobjective of this study was to explore which strategywould give a balance between solar heat gainreduction and daylight utilization and result in themost energy savings in the building.Computer simulations using an hourly energycalculation model were conducted to predict thebuilding's total energy consumption using eachstrategy. The economics of each strategy wereanalyzed with lifecycle costing techniques using thepresent value technique. Results show that properlydesigned overhangs that shade clear glazing areslightly more cost-effective than specialized low-eglazing systems. These results are unique for hothumid climates where winter heating is not an issue.On the contrary, when used in cold climates,external shading devices tend to increase the building's energy consumption.