General Questions about Cool Roofing

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1.) Are cool roofs affordable? 

Yes.  Many cool roof varieties cost the same amount as other comparable roofing materials, and for those that cost slightly more, the difference can usually be quickly recovered in savings from reduced energy costs.

2.) Can you tell me which product is best for me?

No. While we can answer many general questions about the radiative properties of roofs, we cannot recommend specific products or types.  Once you have looked at our Rated Products Directory we encourage you to contact the manufacturers of the products in which you are interested, or contact a private contractor or roof consultant to assist in choosing the “coolest” product for your home or project.

3.) Are there other “cool” options besides  white roof coatings?

Yes.  Cool roofs are available in almost every common product type and come in an unlimited range of colors – including “cool” black in some cases.  Take your pick!

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4.) Will Cool roofs significantly increase my heating bills in the winter months?

No. The roof is an insignificant source for heat gain in winter.  While cool roof owners may pay slightly more to heat their homes, this amount is usually insignificant compared to the cooling energy savings during the summer. Why?

• In the wintertime, the sun is much lower in the sky and less intense.  (Passive solar heating usually occurs from sunshine streaming through windows this time of year).
• There is a higher incidence of cloudy days, and in some regions the roof is covered in snow for long periods.
• Winter days are shorter (fewer hours of sunshine)
• A cool roof will not shed more heat proportionate to other types of roofing materials at night or on cloudy days.  It will simply limit the amount of heat entering the building on hot summer days

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5.) What are Solar Reflectance and Thermal Emittance?
Solar reflectance and thermal emittance are the two radiative properties used to measure the "coolness" of a roof.

6.) How do I compute the Solar Reflectance Index (SRI) of a roofing product?

SRI is an alternative method for considering the radiative properties of roofing materials. SRI is defined by ASTM Standard E1980-01 and is a calculation that uses solar reflectance and thermal emittance.  EPA summarizes SRI as “the relative steady-state surface temperature with respect to the standard white (SRI=100) and standard black (SRI=0) under the standard solar and ambient conditions.”  SRI is often usedalternative is designed for products that have a low thermal emittance but a very high solar reflectance—the theory is that the higher solar reflectance will outweigh the impact of a low thermal emittance.

The CRRC Product Directory does not include SRI, however, the provided solar reflectance and thermal emittance values can be used to compute SRI.  The US Green Building Council uses SRI for some of their LEED rating systems cool roof credits. They have a calculator posted at http://www.usgbc.org/DisplayPage.aspx?CMSPageID=1447. From there, click on the NC2.2 SS link and, when prompted, click "open". Open the "SSc71_2.2a" pdf file.

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If you have a question that has not been answered on this page, see CRRC-1 (the CRRC's Program Manual) or contact us: e-mail us at info@coolroofs.org or call us at (866) 465-2523 (toll free in the U.S.) or (510) 485-7175.