Simulated Impact of Roof Solar Absorptance, Attic, and DuctInsulation, and Climate on Cooling and Heating Energy Use inSingle-Family Resi dential Buildings

This report summarizes a comparative analysis of the impact of roof surface solar absorptance, attic, and duct insulation on simulated residential annual cooling and heating energy use in sixteen sunbelt climates. These locations cover a wide range of climates where cool roofs are expected to save energy and money, and are areas with high growth rates in new residential construction. The residences are single-story, single-family of new construction with either a gas furnace or an electric heat pump, and with ducts in the attic OT conditioned zone. The objective is to demonstrate that a residence with a cool roof could utilize a lower level of attic insulation than one with a dark roof with a zero net change in the annual energy bill. Annual energy use is simulated with DOE-2. lE, which was adapted with a validated residential duct-attic function, for dark and cool roofs and eleven attic insulation R-values ranging from 1 through 60. Analysis of the simulated energy savings from the light-colored roofs show that the savings can be transformed into an equivalent reduction in the level of attic insulation. Reductions in R-value are observed in varying degrees for residences with both gas and electric heat, all duct configurations, and all climates. In some cooling dominated climates there are cases where a cool roof could be implemented without attic insulation