Next-Generation Roofs and Attics for Homes

Panel: Residential Buildings: Technologies, Design, Performance Analysis, and Building Industry Trends

Authors:
William Miller, Oak Ridge National Laboratory
Jan Kośny, Oak Ridge National Laboratory

Abstract

Prototype residential roof and attic assemblies were constructed and field tested in a mixed-humid U.S. climate. Summer field data showed that at peak day irradiance the heat transfer penetrating the roof deck dropped almost 90% compared with heat transfer for a conventional roof and attic assembly. The prototype assemblies exhibited attic air temperatures that did not exceed the peak day outdoor air temperature. The assemblies use a combination of strategies: infrared reflective cool roofs, radiant barriers, above-sheathing ventilation, lowemittance surfaces, insulation, and thermal mass to reduce the attic air temperature and thus the heat transfer into the home. Field results were benchmarked against an attic computer tool and simulations indicated that retrofitting pre-1980 construction with prototype roof systems and improving ductwork by reducing air leakage and heat transfer to existing ducts in attics could yield annual savings of about $200. In the hot, dry southeastern region of California, the combined ceiling and duct annual load drops by 23% of that computed for a code-compliant roof and attic assembly.