Want greater energy savings? The answer is right above you
Not all energy saving products and techniques are equal. In fact, not all of them are even widely known.
Recently, a study funded by the U.S. Department of Energy and conducted by the Oak Ridge National Laboratory (ORNL) found significant cost savings by creating air space under metal roofing systems.
The study compared the possible energy savings of metal vs. asphalt roofs by doing field testing on an asphalt shingle roof and a stone-coated metal shake roof, both with comparable solar reflectance and thermal emittance levels. The asphalt shingle was directly nailed to the roof deck, with no air space underneath, while the dark-gray metal shake was attached to a batten/counter-batten system that allowed for airflow underneath.
The scientists from ORNL discovered a 45% reduction in heat flow for the metal shake; about 15% of that reduction was attributed to solar reflectance and an additional 30% of the heat flow reduction was due to above-sheathing ventilation.
In cool or cold weather conditions, scientists confirmed that direct-nailed asphalt shingle roofs had significantly larger heat loss than attics with metal shakes and above-sheathing ventilation. The air gap appears to serve as an insulating layer, reducing heat transfer by 50% as compared to asphalt.
The study results have been corroborated by Florida Solar Energy Center and accepted by the ASHRAE SSPC 90.1 subcommittee, indicating that any type metal roof can save a home or building owner up to 25% in annual cooling energy costs compared to a dark-gray asphalt shingle.
About the Author
Jeff Alexander
Jeff Alexander, Sherwin-Williams Coil Coatings VP of Sales for the Coil and Extrusion division has been with Sherwin-Williams (formerly Valspar) since 1997. He has an entrepreneur spirit and has thrived in building relationships with our customers. Jeff has fully immersed himself in all levels of the coating industry and enjoyed his term as National President at NCCA (National Coil Coating Association). He is focused on continuing to educate customers on the paint industry.