The Short Answer
Light colors stay coolest. On Zia Metal Roofing Supply's lab-tested color chart, Ivory (SRI 80) and Polar White (SRI 78) reflect the most sun, followed by Light Stone (66). Dark blues, greens and blacks sit at the bottom, between 24 and 29. In Albuquerque, where roofs take strong high-altitude sun most of the year, the color you pick makes a real difference to how hot the roof surface gets.
What SRI Means
SRI stands for Solar Reflectance Index. It combines two measurements into one number:
- Solar reflectance: the share of sunlight the surface bounces away, from 0 to 1. Higher is cooler.
- Thermal emittance: how well the surface sheds the heat it does absorb, from 0 to 1. Higher is cooler.
On the SRI scale, a standard black surface scores 0 and a standard white surface scores 100. The higher the number, the cooler the roof surface stays in direct sun.
Zia's Tested Colors, Coolest to Warmest
These results come from a Sherwin-Williams Coil Coatings certified laboratory test report (No. 2024-2131R) for WeatherXL paint on Galvalume steel, published in Zia's product brochure. Solar reflectance was measured under ASTM C1549, thermal emittance under ASTM C1371, and SRI calculated under ASTM E1980 at medium wind speed.
| Color | Solar reflectance | Thermal emittance | SRI |
|---|---|---|---|
| Ivory | 0.66 | 0.87 | 80 |
| Polar White | 0.65 | 0.86 | 78 |
| Light Stone | 0.56 | 0.87 | 66 |
| Copper Penny | 0.48 | 0.84 | 54 |
| Timber Tan | 0.47 | 0.87 | 53 |
| Ash Gray | 0.46 | 0.87 | 52 |
| Red | 0.39 | 0.86 | 42 |
| Charcoal | 0.36 | 0.86 | 38 |
| Evergreen | 0.35 | 0.88 | 38 |
| Cocoa Brown | 0.33 | 0.87 | 35 |
| Crimson Red | 0.33 | 0.88 | 35 |
| Hawaiian Blue | 0.32 | 0.86 | 33 |
| Burnished Slate | 0.32 | 0.87 | 33 |
| Black (WXA0107L) | 0.29 | 0.87 | 29 |
| Green | 0.28 | 0.87 | 27 |
| Black (WXA0117L) | 0.26 | 0.88 | 26 |
| Gallery Blue | 0.26 | 0.85 | 24 |
Two notes from the report itself: the panels were tested unwashed, and the measurements are not intended for ENERGY STAR certification. Two different blacks appear because Sherwin-Williams tested two black paint codes.
What This Means on an Albuquerque Roof
Albuquerque sits above 5,000 feet, so there's less atmosphere to filter sunlight than at sea level, and summer afternoons bake south- and west-facing roof slopes. A cooler roof surface means less heat soaking into the attic, which can ease the load on a swamp cooler or AC. How much depends on attic insulation and ventilation, so a light roof doesn't replace either one.
A few practical points we share with homeowners:
- The middle of the chart is a good compromise. Light Stone, Copper Penny, Timber Tan and Ash Gray score between 52 and 66. They stay far cooler than dark colors without the bright look of white.
- Glare matters on low roofs. Ivory and Polar White can be bright from second-story windows or neighbors' yards.
- HOAs may decide for you. Some HOAs limit roof colors, so check your community's rules before you choose.
- Dust dulls reflectance. Spring wind leaves dust on every roof, and the lab tested clean, unwashed panels, so a dusty roof reflects somewhat less than the chart shows.
Color availability varies by profile and gauge, and Zia stocks some colors as premium options. We'll confirm what's available for the profile you choose. See Zia's five metal roofing profiles and metal roof cost in Albuquerque.