What Is Cool Roofing? CRRC Ratings & Benefits

A "cool roof" reflects the sun's heat instead of absorbing it, lowering cooling bills and indoor temperatures. Interlock's Alunar® colors are CRRC-rated, with initial solar reflectance of 0.25–0.44 and thermal emittance of 0.83 to 0.86 — in a range of colors, not just white.

On a hot afternoon, two identical houses can feel completely different inside — and the difference is often what's reflecting, or absorbing, the sun overhead.

A "cool roof" is simply a roof engineered to bounce solar energy away rather than soak it up. Dark asphalt absorbs most of the sunlight that hits it and radiates that heat down into the attic; a reflective surface sends much of it back to the sky.

Cool performance is measured, not marketing. The Cool Roof Rating Council (CRRC) has tested products for two decades on two numbers — solar reflectance and thermal emittance — and publishes the results. Several of Interlock's aluminum colors are rated, in real colors, not just white.

What is cool roofing?

Cool roofing is roofing engineered to reflect sunlight and release absorbed heat quickly, measured by two values: solar reflectance and thermal emittance. The Cool Roof Rating Council (CRRC) tests both. Several of Interlock's Alunar® aluminum colors are CRRC-rated, with initial solar reflectance up to 0.44 and thermal emittance of 0.83 to 0.86.

What Makes a Roof a "Cool Roof"

Two measured properties define cool roofing. Solar reflectance is the fraction of sunlight the surface bounces away (0 to 1 — higher is cooler). Thermal emittance is how readily the surface releases the heat it does absorb (also 0 to 1 — higher means it cools down faster). A genuine cool roof scores well on both. The Cool Roof Rating Council has independently rated these values for more than 20 years.

Interlock's CRRC-Rated Colors

Interlock's Alunar® PVDF finish is engineered for reflectance, and several colors are rated by the Cool Roof Rating Council. The CRRC lists initial solar reflectance from 0.25 up to 0.44 (Aged Copper is highest) and thermal emittance of 0.83 to 0.86. This reflective performance is a core part of what makes metal roofing energy efficient; see Maximizing Energy Efficiency: The Benefits of Metal Roofs for the fuller picture.

Cool Roofing Isn't Only White

The biggest myth about cool roofs is that they must be white or pale. Modern reflective coatings like Alunar® use pigment technology that reflects a large share of the sun's near-infrared energy — the part you can't see but that carries most of the heat — even in darker colors.

The Benefits: Savings, Comfort, and Color

A reflective roof pays you back in three ways. Less heat gain: Lighter colors reflect more summer sun; actual savings depend on climate, color, insulation and ventilation. More comfort: upstairs rooms and west-facing spaces stay noticeably cooler in summer. And design freedom: because Alunar® performs across the palette, you keep full control of curb appeal.

Cool Roofs and the Environment

Cool roofing scales from the single home to the city. Across a metro area, dark roofs and pavement contribute to the urban heat-island effect, which raises summer air temperatures and cooling demand. Interlock adds a second environmental win as part of the broader case laid out in Investing in a Sustainable Future: the panels are recyclable at end of life, and that same reflective surface is one reason Interlock roofs are considered solar friendly.

Is a Cool Roof Right for You?

If you pay to cool your home for any meaningful part of the year, a cool roof is one of the few upgrades that starts paying back immediately and keeps doing so for decades.