The Oak Ridge National Laboratory (ORNL), an acclaimed laboratory dedicated to research for the U.S. Department of Energy, completed a study that provides authoritative verification that DECRA stone-coated steel roofs contribute to outstanding energy savings and unsurpassed thermal performance.
When it comes to improving energy-efficiency with a roof upgrade, there are three physical characteristics to increase, also known as thermal performance:
Thermal Resistance: The insulation value of the entire roof.
Emissivity: The ability of the roof to radiate solar heat gains up and away from the house or building.
Reflectivity: The ability of the roof to reflect radiant heat back to the direction from which it came.
ORNL tested thermal performance characteristics of DECRA stone-coated metal roof systems installed on a variety of test roofs. The extensive testing period ran through the natural cycle of winter and summer seasons.
Scalloped style tile and cool roof metal shake panels were used to compare performance against conventional asphalt shingles on steep-sloped roofs.
Significant enhanced thermal performance were verified by the ORNL studies including:
- Infrared-blocking pigments in DECRA cool roof stone granule coatings. Infrared radiation from the sun is the source of heat. While asphalt roofs absorb heat like a sponge and transfer it down into the home, DECRA infrared blocking pigments increase the natural solar reflectance characteristic of metal roofs. DECRA stone coatings with essential infrared blocking cool roof colors can perform even better than uncoated standing seam metal roofs.
- Batten metal roof installations enhanced underside roof system venting. Battens are simply a grid of wood strips that provide a critical air space between the roof system and the underlying roof deck. With a ridge vent at the highest point of the roof hot air rises naturally and escapes to the atmosphere. Battens function as a super-efficient heat elevator in the summer and provide an extra insulating air space in cold winter weather.
- Reduced heat flow is accomplished with both DECRA direct-to deck and batten installations. Compared to asphalt shingles, DECRA cool roof colors with infrared blocking pigments reduced heat flow by 15%. Sub-roof venting with batten installations reduced heat flow by 30%.
What Were the Best Thermal Performing Test Roofs?
The best thermal performing roofs were the DECRA Tile roof and the light gray cool roof DECRA Shake roof on battens over counter-battens. Battens run vertically on the roof under counter-battens beneath running horizontally across the roof. Of course, installing counter-battens doubles the thickness of the venting air space (also known as “above sheathing ventilation” or ASV) allowing an even broader path for heat to escape through the ridge vent.
The reduction in heat penetrating the ceilings of these roofs was 70% better than the asphalt shingle roof measured in identical test conditions.
While a 70% heat reduction is impressive, DECRA roofs can also save time and labor expenses.
ORNL tests showed that reroofing with a stone-coated metal shake roof over an existing cedar shake roof proved to be beneficial and resulted in the best thermally performing system, reducing ceiling heat flow by 75% over that of an attic with a conventional asphalt shingle roof.
About DECRA Metal Roofing
DECRA is the innovator of stone-coated steel roofing products with ageless beauty and lifetime durability. DECRA has been setting the gold standard of excellence in the roofing industry for more than 60 years and all DECRA products are made right here in the U.S. at our state-of-the-art facility in Corona, California. When you’re ready to join more than 1 million satisfied DECRA homeowners, contact an expert DECRA roofing advisor today.
