ORNL roof, attic design proves efficient in summer, winter

A new roof-and-attic system tested at the Oak Ridge National Laboratory keeps homes cool in summer and prevents heat loss in winter, a press release said.

Among the features designed to improve efficiency are a ventilation system that pulls air from the underbelly of the attic into air space above the roof, the release said.

“Heat that would have gone into the house is carried up and out,” says Bill Miller of ORNL’s Building Envelope Group. “And with a passive ventilation scheme, there are no moving parts, so it’s guaranteed to work.”

The release said the new roof system can be retrofitted with almost all roofing products.

“The heart of the design is a foiled, covered polystyrene insulation that fits over and between rafters in new construction or can be attached on top of an existing shingle roof system,” the release said. “Homeowners don’t have to remove old shingles, which saves money.”

It said attics can be retrofitted for about $2,000, and homeowners can save $100 per year. The system costs less than, and has the same payback period as, the spray foam used by many homeowners concerned about air leaking into their attics. The spray foam can cost $8,000, the release said.

It said Miller and his colleagues are working on designs with lower installation costs and greater overall cost-effectiveness.

A paper on the roofing system titled “Prototype Roof Deck Designed to Self-Regulate Deck Temperature and Reduce Heat Transfer” was published by the National Roofing Contractors Association. The authors were W. Miller, Stan Atherton, and Russell Graves of the University of Tennessee in Knoxville, and Billy Ellis of Billy Ellis Roofing.

Funding was provided by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy and Billy Ellis Roofing under a user agreement.