Trade-off between cool roofs and attic insulation in new single-family residential buildings
This paper summarizes a comparative analysis of the impact of roof surface solar absorptance and attic insulation on simulated residential annual cooling and heating energy use in sixteen sunbelt climates. The buildings are single-story, single-family, new construction residences with either a gas furnace or an electric heat pump and with ducts in the attic or conditioned zone. Annual energy use is simulated with DOE-2 for dark and cool roofs and eleven attic insulation R-values ranging from 1 through 60. The simulations are regressed as a function of roof system conductance and roof absorptance for each heating system, duct location/insulation level, and climate. An equivalent change in conductance is calculated for a given change in absorptance from a dark to a cool roof. Equivalent attic insulation R-values are found from the conductance of the cool roof. Reductions in R-value are observed in all buildings and climates. The analysis demonstrates that a roof system with a cool roof and low attic insulation can be used as an alternative to the more conventional dark-colored roof with a high level of insulation, with a zero net change in the annual energy bill. Similar work was previously done in support of revisions to ASHRAE commercial building standard 90.1.
- Research Organization:
- Lawrence Berkeley National Lab., CA (US)
- Sponsoring Organization:
- US Department of Energy
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 20001983
- Report Number(s):
- CONF-980815--
- Country of Publication:
- United States
- Language:
- English
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