Over the Top

Cool Technology for “Hot as a Firecracker” Days

Submitted by Deveny Coryell, Editor, Coryell Roofing & Construction

Well, it’s July and hot as a firecracker in Arkansas, with air conditioning units working overtime to keep inside temperatures comfortable. If soaring utility bills are making you sweat, you may want to consider a cool roof—one that has both solar reflectance and thermal emittance.

A Cool Roof Has Solar Reflectance - This means that the roof’s surface material or coating is designed to highly reflect solar rays. The greatest degree of solar reflectance is achieved with white or light-colored surface materials. On a 90-degree day, a dark roof surface, especially a dark metal surface, can heat to 190 degrees and take hours to cool after the sun has set. The built-up heat then penetrates the roof’s surface and radiates into the building. On the other hand, a white or light-colored roof surface can reflect 60% to 90% of the solar rays and heat to only 9 degrees above the air temperature. For example, a DuroLast white membrane reflects up to 90% of the sun’s rays, keeping the roof’s surface 50 to 80 degrees cooler than darker roof surfaces.

A Cool Roof Has Thermal Remittance - Solar heat that is not reflected is absorbed by the roof. Cool roofs are designed to readily release this absorbed heat, keeping the roof surface and building temperatures cooler. This is referred to as thermal remittance. While many roofing materials have a high degree of thermal remittance, the degree of remittance must be measured and a high degree of remittance achieved for a roof to qualify as a cool roof. A roofing specialist can educate you about materials that qualify.

Cool roof options for almost every roof type are available: single-ply membranes, modified bitumen, metal retrofits, etc. The Coryell Roofing team is knowledgeable in cool roof options and trained to run energy efficiency reports that calculate the rough energy savings you could realize by installing a “cool roof system.” Until next month, all the folks at Coryell Roofing send wishes for a relaxing and refreshing summer for Arkansas administrators. Stay cool!