You might be surprised to learn that metal roofing actually keeps homes cooler than asphalt shingles. In one Florida test, the attic under a white standing seam metal roof was measured about 22 °F cooler than rival options. While Northeast Ohio and Western Pennsylvania aren’t as sunny as Florida, the same pattern holds: reflective, high‑emissivity metal runs cooler than dark asphalt.
What’s even more interesting, though, is which roof came in last, and why it lost.
The Two Things That Make a Roof Cool
So, how do metal roofs keep your house cooler? There are two key jobs for a roof on a hot day: solar reflectance and thermal emissivity.
- Reflectance is how much sunlight the roof bounces away before it can turn into heat.
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Emittance is how quickly the roof can let any absorbed heat escape back into the sky instead of pushing it down into your attic.
Energy Star reports that “An ideal cool roof is a roof with both high solar reflectance (SR) and high thermal emittance (TE).”
What the Measurements Tell Us
The Florida Solar Energy Center at the University of Central Florida runs an instrumented test facility in Cocoa, Florida where they tested the question: are metal roofs cooler than shingles?
For this study, they used black shingles as a control while comparing them against different metal roofing options. All test cells had R-19 attic insulation and identical construction. Reflectance values were lab-tested to ASTM E-903, and emittance to ASTM E-408.
| Roof surface | Solar reflectance | Thermal emittance | Attic vs. the shingle control |
|---|---|---|---|
| Black asphalt shingle (control) |
2.7% | 0.90 | baseline |
| White standing seam metal |
67.6% | 0.83 | 22.2 °F cooler |
| Bare Galvalume metal |
64.6% | 0.28 | 10.9 °F cooler |
| Bare galvanized metal |
70.9% | 0.04 | 2.1 °F cooler |
The bare metal panels in this test are not what we at Distinctive Metal Roofing install on homes. Researchers used them to isolate how different surface coatings affect temperature. For real homes, we use factory‑painted panels designed to balance both reflectance and emittance.
You can verify a product’s rated reflectance and emittance yourself by consulting the Cool Roof Rating Council directory.
As the table above shows, bare galvanized metal cooled the attic the least compared to the control. Why would the shiniest roof result in the warmest temperature?
Why the Most Reflective Roof Performed Worst
Bare galvanized reflected more sunlight than the white standing seam and still finished nearly last. Low-emissivity surfaces run hotter because they cannot give collected heat back to the sky.
Is It Harder to Cool a House with a Metal Roof?
No, in fact, attics with metal roofs installed on the roof deck measure 30 degrees fahrenheit cooler so it’s easier. Because traditional asphalt shingles aren’t reflective and absorb and hold the sun’s heat long into the evening, they constantly force your air conditioning system to work overtime to cool your living spaces.
Our metal roofs receive a Kynar 500 finish. The pigments in the factory paint coating is what gives the panel high reflectivity and the metal sheds absorbed heat quickly instead of holding it into the evening.
Winter Effects for Cleveland and Pittsburgh
The winter sun is weaker, the days are shorter, and your roof is often under snow anyway, so there’s far less solar gain for any roof to reflect. In our climate, winter heat retention is driven far more by your attic insulation and air sealing than by your roof surface.
Lower Your Attic Temperature with a Metal Roof
A metal roof with a Kynar finish can significantly reduce how much heat your roof holds onto, which makes it easier for a properly ventilated attic and a good AC system to keep your home comfortable. Plus, your new roof can help reduce wasted energy and cut down on how often you need to replace roofing materials.
If you’re wondering how a modern metal roof would perform on your specific home, get a free metal roofing estimate from experts who actually understand the ever-changing weather of Cleveland and Pittsburgh. Contact our team today for assistance.