White Vs Black Roof Reflactance

The environmental benefits of exposed membrane low slope roofing systems with high solar reflectance and thermal emittance have been established by the cool roof rating council crrc lawrence berkeley national laboratory and others.

White vs black roof reflactance.

Single ply membranes are pre fabricated sheets rolled onto the roof and attached with mechanical fasteners adhered with chemical adhesives or held in place with ballast gravel stones or pavers. Reformulate or coat black membranes to make them reflective. Solar reflectivity or reflectance is the ability of a material to reflect solar energy from its surface back into the atmosphere. Sri measures the roof s ability to reject solar heat defined such that a standard black reflectance 0 05 emittance 0 90 is 0 and a standard white reflectance 0 80 emittance 0 90 is 100.

The sr value is a number from 0 to 1 0. How they can be made cool. A value of 0 indicates that the material absorbs all solar energy and a value of 1 0 indicates total reflectance. However and here is the big kicker a properly ventilated attic space let me say that again properly ventilated was a 2 degree average difference.

Reflective surfaces are a form of geoengineering. Solar reflectivity r solar reflectance index sri by color. When determining if black or white roofing membrane is a better choice for your commercial building there are a few common misconceptions many people encounter. The first being that white membranes are more durable than black membranes due to their lower surface temperature.

And for that reason facility managers have been using light colored roofs for decades to keep their roof temperature low and reduce cooling costs during the hot summer months. Clearly the white fabric reflected the sun s rays and maintained a cooler surface temperature than did the darker fabric. We ve heard this a lot lately. Top 3 myths revealed.

Metal roofing black and white roofs metal roofing is easy to find in both black and white colors and may just be the future of roofing due to the decreasing cost of metal as a material. This principle is the same at work on a cool roof. The most well known type of reflective surface is the cool roof. What they found was surface temprature hand to shingle was approximately 20 degrees warmer if black.

In fact city councils throughout the country are adopting model codes which favor white over black roof systems touting energy efficiencies without considering key factors that greatly contribute to the actual efficiency and life of a roof. Incorporates both solar reflectance and thermal emissivity in a single value. There s much more to selecting a roof membrane than color but it s not a black and white decision. White roofs are better than black roofs.

White metal has the highest rate of solar reflectivity than any other material and a large portion of california cool roofs are created with metal.