Solar Reflectance, Emissivity, and Metal Roofing

Metal roofing from Tri County Metals is one of the most energy efficient roofing materials available and can save your home up to 40% in energy costs and provide excellent energy savings during the hot Florida summers – or anywhere in the southern US for that matter. The secret to metal roofing's energy savings is in its variety of finishes.

When compared to shingles, even bare Galvalume, also called “Mill Finish” (meaning it has no painted finish) reflects more heat radiation than asphalt shingles. Asphalt shingles absorb heat, while metal roofs, in general, will reflect that UV radiation and cause the attic space of the home to not get as hot as homes with shingles roofs.

So by definition, Solar Reflectance, also denoted as “SR” on our color charts, in relation to metal roofing refers to UV and Infrared light rays being reflected from the roof surface. These rays are what impact the heating / cooling of the roof surface.

See the illustration below and note the difference in attic temperatures between the shingle roof on the top, and the metal roof on the bottom. 

 

The real energy savings, however, comes not just with a mill finish metal roof, but a highly reflective and highly emissive painted or granular-coated metal roof. The paint pigments allow for a reducing of energy consumption and can re-emit up to 90% of absorbed solar radiation.

So by definition, Emissivity, also noted as “E” on our color charts, is the characteristic of the painted metal roofing panel to release heat energy back into the atmosphere and away from the attic, and we can measure how quickly that release occurs. The higher the Emissivity, or “E”, number on our color chart, the faster that heat is released. 

The most effective energy-saving finish for metal roofing is commonly referred to as cool-metal roofing. This highly reflective coating uses cool pigments in the paint to increase solar reflectance and lower the surface temperature of the roof.

It is worth noting that all our color painted panel offerings at Tri County Metals are cool roof colors.

Cool-metal roofing systems help reduce the energy need of air-conditioned buildings and makes unconditioned buildings more comfortable.

And don’t just take our word for it, read more on the Metal Roofing Alliance website.