Introduction

Cool Metal Roofs: ENERGY STAR and CRRC Ratings Explained

Published 2026-03-13

A "cool roof" is a roof surface that reflects more solar energy and emits more absorbed heat than a conventional roof. Two programs certify cool metal roofing: (EPA certification with minimum reflectance thresholds) and (independent testing that publishes both initial and aged reflectance/emittance values). For the Gulf Coast, where cooling loads dominate 7-9 months of the year, a cool-rated metal roof is one of the most practical energy investments available.

What Makes a Roof "Cool"

A cool roof has two measurable properties: high and high . Reflectance determines how much solar energy the surface bounces back. Emittance determines how efficiently the surface radiates absorbed heat away. A roof needs both properties to be "cool" — high reflectance alone is not sufficient if the surface traps the heat it absorbs, and high emittance alone is not sufficient if the surface absorbs too much heat in the first place.

Painted metal roofs naturally excel at both. The and paint systems applied to metal roofing panels are engineered to reflect solar radiation. PVDF coatings in particular maintain their reflective properties for 30-40 years with minimal degradation. And all painted metal surfaces have thermal emittance of 0.80-0.90, meaning they efficiently re-radiate whatever heat they do absorb.

The "cool" designation is relative to a baseline. Standard dark asphalt shingles have solar reflectance of 0.05-0.15 and SRI of 0-10. Any roofing product that significantly exceeds this baseline is considered "cool." Most light-to-medium metal roof colors exceed the baseline by a large margin. Our reflectivity by color guide lists the exact solar reflectance values for common metal roof colors.

ENERGY STAR for Roofing Products

What ENERGY STAR Requires

ENERGY STAR is an EPA certification program that sets minimum performance thresholds for energy-efficient products. For steep-slope roofing products (residential roofs with slopes greater than 2:12), ENERGY STAR requires:

Property Initial Requirement Aged (3-Year) Requirement
Solar Reflectance 0.25 or higher 0.15 or higher

No thermal emittance minimum is specified for ENERGY STAR steep-slope roofing. However, the equivalent of 0.25 solar reflectance with typical painted metal emittance (0.85) is approximately SRI 25. Products must be tested and verified through the CRRC or an EPA-recognized test procedure.

Which Metal Roofs Qualify

Most light-to-medium colored -coated metal roofs easily meet ENERGY STAR requirements. White, ivory, tan, light gray, light blue, light green, and many medium tones achieve initial solar reflectance of 0.25 or higher. Some darker colors with infrared-reflective (IR) pigment technology also qualify — these special pigments reflect infrared energy (which carries heat) even while absorbing visible light (which provides the color).

Standard dark colors (charcoal, black, dark bronze) without IR pigments typically do not qualify. Their initial solar reflectance falls below 0.25. However, the same dark color formulated with IR-reflective pigments may achieve 0.25-0.35 initial reflectance and qualify. If you want a dark-colored ENERGY STAR roof, ask specifically for IR-reflective formulations.

What ENERGY STAR Does Not Tell You

ENERGY STAR is a pass/fail threshold, not a performance ranking. A metal roof with 0.26 initial reflectance and one with 0.72 initial reflectance both carry the ENERGY STAR label. The difference in actual energy performance is enormous, but the label does not distinguish between them. For meaningful comparison, you need the specific reflectance and SRI values — which is where CRRC comes in.

CRRC: The Cool Roof Rating Council

What CRRC Does

The is an independent organization that tests, rates, and publishes the solar reflectance and thermal emittance of roofing products. Unlike ENERGY STAR (which sets a threshold), CRRC publishes the actual measured values — both initial and aged (3-year weathered). This allows direct, quantitative comparison between products.

CRRC's Rated Products Directory is the most comprehensive public database of roofing energy performance. It lists thousands of products with their tested reflectance, emittance, and calculated SRI values. You can search by manufacturer, product type, color, and performance range. For homeowners comparing metal roofing options, the CRRC directory provides the objective data needed to make an informed decision.

How CRRC Testing Works

Manufacturers submit product samples to CRRC-accredited laboratories for testing. Initial solar reflectance is measured per ASTM C1549 or ASTM E903. Initial thermal emittance is measured per ASTM C1371 or ASTM E408. These are the "initial" values published in the directory.

Aged values are measured after 3 years of outdoor weathering. CRRC maintains weathering farms in multiple U.S. climate zones where samples are exposed for 3 years. After aging, reflectance and emittance are re-measured. The aged values represent the performance after the initial soiling and weathering that all roofs experience. Aged values are always lower than initial values due to dirt accumulation, oxidation, and UV degradation.

PVDF-coated metal retains its reflectance better than most other roofing materials. Typical PVDF metal roof reflectance degradation after 3 years is 5-10% (e.g., 0.65 initial to 0.58-0.62 aged). By comparison, asphalt shingles with reflective granules may lose 20-30% of their initial reflectance. SMP-coated metal falls between the two. This retention advantage is another reason PVDF is the standard for energy-conscious metal roofing.

How to Read a CRRC Listing

A CRRC listing for a metal roofing product typically includes:

  • Product ID: Manufacturer's product name and color
  • Initial solar reflectance: Measured value (0-1 scale)
  • Aged solar reflectance: 3-year weathered value
  • Thermal emittance: Typically 0.83-0.90 for painted metal
  • SRI (initial): Calculated from initial reflectance and emittance
  • SRI (aged): Calculated from aged reflectance and emittance
  • ENERGY STAR eligible: Whether the product meets ENERGY STAR thresholds

Focus on aged values for realistic performance expectations. Initial values represent the roof on day one. Aged values represent the roof after it has been exposed to real-world conditions. The aged SRI is the number that most closely predicts long-term energy performance.

Infrared-Reflective Pigments: Cool Colors in Dark Tones

Traditional pigments achieve high reflectance by being light-colored — they reflect visible light, which carries about 43% of solar energy. But infrared radiation carries about 52% of solar energy. If a pigment can reflect infrared while absorbing visible light, it can be dark-colored and still reject a significant portion of solar heat.

IR-reflective pigments do exactly this. They are formulated to be transparent to near-infrared radiation while absorbing specific visible wavelengths to produce the desired color. A dark gray metal roof with IR-reflective pigments might have solar reflectance of 0.30 — far less than white (0.70) but far more than the same dark gray with standard pigments (0.12).

The practical impact is meaningful but not dramatic. An IR-reflective dark metal roof saves approximately 5-12% on cooling compared to standard dark shingles, versus 20-30% for a white metal roof. It is a significant improvement over doing nothing, but it does not make a dark roof perform like a light one. IR-reflective pigments narrow the gap between dark and light, but they do not close it.

Availability is growing. Major metal roofing manufacturers now offer IR-reflective formulations in their most popular dark colors. Ask specifically whether the dark color you are considering uses IR-reflective pigments. Not all dark-colored metal roofs include this technology, and the difference in performance is significant enough to matter.

Coating System and Energy Retention

The coating system affects not just initial energy performance but long-term retention. coatings maintain their solar reflectance significantly longer than coatings.

Property PVDF SMP
Initial solar reflectance (white) 0.65-0.75 0.60-0.70
3-year aged reflectance (white) 0.58-0.68 0.48-0.58
10-year estimated reflectance (white) 0.55-0.65 0.35-0.45
Chalking resistance 30-40 years 15-20 years
Reflectance retention over 20 years Retains 80-90% of initial value Retains 50-65% of initial value

The implication for energy performance is significant. A PVDF roof that starts at 0.70 reflectance and retains 0.60 after 20 years continues to deliver meaningful energy savings throughout its life. An SMP roof that starts at 0.65 but drops to 0.40 after 20 years has lost nearly half its energy benefit. Over a 30-40 year roof life, PVDF delivers substantially more cumulative energy savings.

Common misconception

Any metal roof is a 'cool roof.'

Reality: A metal roof is only a cool roof if it has the right coating and color. Bare (unpainted) Galvalume has very low thermal emittance and can trap heat on the roof surface, potentially performing worse than painted surfaces. Dark-colored metal with standard pigments may not meet ENERGY STAR thresholds. The combination that makes a cool metal roof is: painted finish (PVDF or SMP) in a light-to-medium color with verified CRRC ratings. Material alone does not make a cool roof — surface properties do.

Code Requirements and Incentives for Cool Roofs

Gulf Coast building codes increasingly incorporate cool roof provisions. The International Energy Conservation Code (IECC) allows cool roofs as a compliance path for energy code requirements. Some jurisdictions offer permit streamlining or reduced insulation requirements for roofs that meet cool roof thresholds.

Federal tax credits may apply. ENERGY STAR-qualified metal roofing may qualify for the Energy Efficient Home Improvement Credit (Section 25C), which covers 30% of qualified product costs up to $1,200 annually for roofing. Eligibility and credit amounts are subject to change — verify current guidelines with the IRS or a tax professional.

Some utility companies offer rebates for cool roof installations. Check with your local utility for available programs. Rebates typically range from $0.10-0.30 per square foot and may require CRRC-rated products meeting specific reflectance thresholds.

Insurance considerations. While cool roof status does not directly affect wind insurance, the overall durability profile of a PVDF metal roof — cool roof properties combined with wind and fire resistance — can positively influence insurance underwriting. Some insurers consider the total roof system quality in their premium calculations.