Solar Reflectance & Emittance: Interlock's CRRC-Rated Values
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Quick answer
Several of Interlock's Alunar-finished aluminum colors are rated by the Cool Roof Rating Council (CRRC), with published initial solar reflectance from 0.25 to 0.44 and thermal emittance of 0.83 to 0.86, depending on color. Lighter colors reflect more summer sun; actual savings depend on climate, color, insulation and ventilation.
What makes a roof a "cool roof"?
On a hot day, a dark, absorptive roof can reach 150–190°F, pushing heat into the attic and forcing the air conditioner to work harder. A cool roof does the opposite: it reflects more of the sun's energy and sheds the heat it does absorb. Two measured numbers define it. Solar reflectance is the fraction of the sun's energy a surface reflects, on a 0-to-1 scale — higher is cooler. Thermal emissivity is how efficiently a surface radiates absorbed heat back out, also 0 to 1 — higher sheds heat faster. A true cool roof pairs high reflectance with high emissivity.
Interlock's CRRC-rated values
These values come from the Cool Roof Rating Council (CRRC) directory listing for Interlock. Black, Charcoal, Deep Charcoal, Colonial Brown, Tudor Brown, Royal Blue and Hunter Green are each listed at an initial solar reflectance of 0.25, thermal emittance of 0.83 and SRI of 22. Tile Red is listed at 0.32 (SRI 31) and Aged Copper at 0.44 (SRI 49). Aged thermal emittance ranges from 0.83 to 0.86. Not every color is listed — Musket Grey, for example, is not — so check the CRRC directory for the current rating of the color you choose.
What does a cool roof actually save?
A reflective roof reduces the heat entering your home through the roof deck, lowering the summer cooling load. Lighter colors reflect more summer sun; actual savings depend on climate, color, insulation and ventilation. The effect is largest on sunny roofs in warm climates, on homes with living space directly under the roof, and where attic insulation is modest.
A note on tax credits and rebates
It is worth being precise. The federal Energy Efficient Home Improvement Credit (Section 25C) expired on December 31, 2025, and roofs were not an eligible improvement under it — so there is no federal tax credit for a cool metal roof in 2026. However, some state, local, and utility programs still offer rebates for reflective or cool roofing, so it is worth checking with your electric utility. See Interlock's tax credits and incentives page for current details.
Frequently Asked Questions
Are Interlock colors rated by the Cool Roof Rating Council?
Several are. The CRRC lists Interlock's rated Alunar colors with initial solar reflectance from 0.25 to 0.44 and thermal emittance of 0.83 to 0.86, depending on color. Lighter colors reflect more of the sun than dark asphalt.
What is solar reflectance and emissivity?
Solar reflectance is the fraction of the sun's energy a surface bounces away (0 to 1, higher is cooler). Thermal emissivity is how efficiently a surface releases absorbed heat (0 to 1, higher sheds heat faster). A cool roof combines high reflectance with high emissivity.
Which Interlock color is the most reflective?
Among the CRRC-rated Alunar colors, Aged Copper has the highest initial solar reflectance at 0.44, followed by Tile Red at 0.32; the darker rated colors are 0.25. Thermal emittance ranges from 0.83 to 0.86, and all Alunar colors share the same durable finish system.
Do cool metal roofs qualify for a federal tax credit in 2026?
No. The federal Energy Efficient Home Improvement Credit (Section 25C) expired December 31, 2025, and roofs were not eligible under it. Some state, local, and utility programs still offer cool-roof rebates, so check with your utility.
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Sources
- Cool Roof Rating Council (CRRC) — Interlock directory listing — Rated colors: solar reflectance, thermal emittance & SRI
- U.S. EPA / ENERGY STAR — Federal Tax Credits for Energy Efficiency — 25C status and expiration
- Cool Roof Rating Council (CRRC) — Rated Products Directory — Current cool-roof ratings
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Last reviewed 2026-07-11 · Reviewed by Scott Plumptree, Director of Marketing, The Interlock Group · Reviewer profile