Green Roof Reflectivity

Solar reflectivity or reflectance is the ability of a material to reflect solar energy from its surface back into the atmosphere.

Green roof reflectivity.

This is a very unfortunate misconception. Green roofs may not reflect as much as a cool roof but do have other benefits such as evapotranspiration which cools the plants and the immediate area around the plants aiding in lowering rooftop. White is the most reflective color and white metal roofing can actually lower the ambient temperature in the home by reflecting more of the sun s rays into the environment. By rich thomas leed ap and steven h.

The sr value is a number from 0 to 1 0. Green roof tab materials d ialog. Solar reflectivity r solar reflectance index sri by color. It has become a leed leadership in energy and environmental design standard of the u s.

Leaf reflectivity the fraction of incident solar radiation that is reflected by the individual leaf surfaces. Commonly referred to as cool roofing it has received a stamp of approval from the state of california which has adopted its use in its building codes. Green roof energy series part 6. Miller cdt to many design professionals the term cool roof means a flat roof with a white membrane a high reflectance roof that performs well but needs to be hidden from view.

Solar radiation includes the visible spectrum as well as infrared and ultraviolet wavelengths. Coating existing asphalt shingles to make them cool however is not normally recommended or approved by shingle manufacturers. Shingle roofs consist of overlapping panels made from a variety of materials such as fiberglass asphalt wood polymers or metals. Still cool neutrals such as medium and muted green.

How they can be made cool. Cool metal roof colors are optimal for reducing energy consumption particularly where cooling loads dominate. The solar reflectance of green roofs varies depending on the plant types generally 0 3 0 5. Berridge metal roofing is cool and sustainable the high reflectivity emissivity and solar reflectance index sri of berridge metal roofing helps mitigate the heat island effect.

White or reflective roofs have been in use for the past 15 years. Cool roofs are pretty cool but whether or not they save as much energy as a green roof requires as usual a closer look at a a cool roof and b a given green roof design. Cool roofs by chris wark energy editor originally posted march 2 2011. Berridge s kynar 500 hylar 5000.

Images courtesy boral roofing. Another option is a vegetative roof that holds plant life and reduces reflective heat. Still the shine of bright white on a roof is imposing and can take away from the overall aesthetic of the house. Values for this field must be between 0 1 and 0 4.

Green building council and has been mandated by government officials in chicago. Buy cool asphalt shingles which use specially coated granules that provide better solar reflectance.