TO-98-17-3 -- Comparative Summer Attic Thermal Performance of Six Roof Constructions PDF

The summer attic thermal performance of six roofs has been measured at a heavily instrumented test site, the Flexible Roof Facility (FRF), which is a 1,152 ft² (107 m²) building with six roof adjacent test cells that are heavily insulated from each other. Some 233 channels of data were obtained; this includes 20 temperature measurements per cell, extensive meteorological conditions, surface and tower wind speeds. and attic humidity and roof surface moisture accumulation. The data were collected over the ASHRAE definition of summer (June - September) to compare the cooling season thermal performance of roofing systems. Six different roof types were evaluated, with variations in color, ventilation, roof mass, and the use of radiant barrier systems (RBS). The tests show that roof system reflectivity greatly influences attic summer temperatures. Two white roofing systems outperformed the other options. Another large improvement comes from greater roof mass; tiled roofs performed better than those with asphalt shingled roofs. An increased attic ventilation rate improved the effectiveness of an attic radiant barrier. Of the evaluated options, a white tile roof best controlled attic heat gain.

Units: Dual