search
cart
facebook twitter linkedin youtube instagram Spotify Podcasts Apple Podcasts Spotify Podcasts Apple Podcasts
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • TOPICS
    • Cool Roofing
    • Event News
    • Latinos in Roofing
    • Low Slope
    • Legal
    • Metal
    • Project Profiles
    • Roofing Supply Pro
    • Roofing Safety
    • Steep Slope
    • Sustainable Roofing
    • Technology
  • EXCLUSIVES
    • Best of Success
    • Contractor Profile
    • IRE Show
    • Roofing Contractor of the Year
      • Enter Roofing Contractor of the Year
    • Top 100
      • Enter the Top 100
    • Young Guns
    • State of the Industry
    • Century Club
  • MULTIMEDIA
    • Videos
    • Podcasts
    • Interactive Spotlights
    • Roofing Quizzes
    • IRE Videos
    • Webinars
    • Photo Galleries
  • PRODUCTS
    • New Products
    • Featured Products
  • COLUMNS
    • Editor's Note
    • Exit Planning
    • Legally Speaking
    • Safety Advice
    • Technical Details
    • Guest Column
  • EVENTS
    • International Roofing Expo
    • Webinars
    • Best of Success Conference
    • Industry Events
  • DIRECTORY
    • Associations
    • Distributors
    • Manufacturer/Supplier
    • Business Services
    • Get Listed
  • MORE
    • Roofing Contractor eNews
    • RC Store
    • Roofing Supply Pro
    • Custom Content & Marketing Services
    • Market Research
    • Sponsor Insights
    • Company Spotlights
    • Classifieds
      • Auctions
      • Business For Sale
      • Business Opportunities
      • Equipment For Sale
      • Positions Available
      • Products
      • Safety
      • Software
      • Services
      • Training
    • Contact Us
  • EMAGAZINE
    • eMagazine
    • Advertise
      • Media Kit
      • Editorial Calendar
      • Contact
    • Archive Issues
  • SIGN UP!
Cool Roofing

Cool Roofs 101

By Jessica Clark LEED AP, Sherry Hao
January 28, 2011
As global interest has increased in passive, energy-saving technologies, cool roofs have received a significant boost in awareness and research over the past year. In both commercial and residential applications, people are discovering the comfort, energy efficiency and climate change mitigation benefits of cool roofs. 

Courtesy of CRRC. 


As global interest has increased in passive, energy-saving technologies, cool roofs have received a significant boost in awareness and research over the past year. In both commercial and residential applications, people are discovering the comfort, energy efficiency and climate change mitigation benefits of cool roofs. Several code bodies and green building programs are catching on as well, with more energy codes specifying cool roof standards. Cool roofs are moving into the spotlight and emerging technologies are pushing the entire industry to a sustainable and energy-efficient future. With heightened demand for this simple yet effective product, several tools have been created to help contractors, building owners and architects specify cool roofs. 

Cool Roof Resources

As there are thousands of product options just for cool roofing, specifying an appropriate roof can be a daunting task. Cool roofs are available in all colors for virtually every roofing type, although white is still the most efficient option. You can gauge the energy performance abilities of a roofing product by understanding how a cool roof reflects and emits the sun’s heat back to the sky instead of transferring it to the building below. Once you understand the basic technology of cool roofing, there are several resources available to help you make a confident, informed decision on your next project.

Solar reflectance and thermal emittance are the two key metrics determining how “cool” a roof will stay by its ability to reflect solar energy and emit absorbed heat. Solar reflectance and thermal emittance will appear as a value between 0 and 1, with a higher value signifying a “cooler” roof. Solar Reflectance Index (SRI) is a third metric that is calculated using a product’s solar reflectance and thermal emittance values. It is measured on a scale of 0 to 100 with a higher number symbolizing a more energy-efficient roof. SRI is sometimes used by code bodies or green building programs in place of solar reflectance and thermal emittance as a single-value alternative. Cool roof standards often specify higher reflectance requirements for low-slope, flat rooftops versus steep-slope, pitched rooftops. This difference in values is due to the energy impact the surface type faces, as the flat surface of a low-slope rooftop is exposed to greater solar radiation than a pitched roof.

Another factor in which roofing products are unique is that they are exposed to outdoor conditions that may alter the energy performing ability of the product. Each product is therefore tested initially as available straight off the shelf, as well as after it has been weathered by outdoor elements. A study by the Oak Ridge National Laboratory and DLR consultants found that the loss of effectiveness of solar reflectance for most roof types leveled out at around three years, so it is an industry standard to test roofing materials after three years of aging to determine their aged value.1 Code bodies sometimes reference this aged value, as it more accurately reflects the performance of the roof through its life cycle.

The Cool Roof Rating Council (CRRC) is a third-party rating program that works with manufacturers to rate their products’ solar reflectance and thermal emittance. The Rated Products Directory is a free online database of roofing products rated by the CRRC (www.coolroofs.org). Code bodies and voluntary green building programs define a cool roof by specifying a minimum value for initial and aged solar reflectance, thermal emittance and SRI, or a combination thereof. The CRRC does not set minimum standards for products to be listed on its Rated Products Directory, but provides unbiased and credible ratings for all products. You can search through more than 2,000 products by categories such as material type, color or manufacturer. You can even search by minimum initial or aged solar reflectance, thermal emittance or SRI value in order to fine-tune your search to products that meet a specific code or program standard.

While code bodies set cool roof minimum standards as guidelines, many people find it more realistic to specify a cool roof based on quantifiable benefits. The U.S. Department of Energy (DOE) and the Environmental Protection Agency (EPA) have both created cool roof calculators to determine energy and monetary savings based on climate, building size, HVAC equipment and other important factors. 
  • The DOE Cool Roof Calculator (www.ornl.gov/sci/roofs+walls/facts/CoolCalcEnergy.htm) offers savings estimates for small- and medium-sized facilities with flat roofs. 

  • The EPA Roof Savings Calculator (www.roofcalc.com) is designed for both residential and commercial buildings, and it allows you to define information about your existing and proposed roofs for comparison.
The cool roof calculators show the tangible savings gained from cool roofs, yet cool roofs offer several other environmental benefits. Eco-conscious designers may also want to consider the cradle-to-cradle aspects of their material choices, including recycled content, end of life recyclability and toxicity of materials.2 

What's Next for Cool Roofs

In July 2010, Secretary of Energy Steven Chu launched an initiative to install cool roofs on DOE and government buildings. Recognition of the benefits of cool roofs, like the DOE initiative, and the development of emerging technologies promises to transform the future marketplace. Several laboratories, universities and companies are already conducting research on new cool roof products, from self-cleaning to thermally sensitive materials to solar panels that take advantage of cool roofs.

 Although they may seem like conflicting technologies, cool roofs can be complimentary to solar photovoltaic panels. According to the DOE, a cool roof can keep the roof surface 50 percent cooler than a dark roof under the same conditions.3 Solar panels may perform more efficiently and for a longer lifespan under the cooler conditions provided by a cool roof. Panels by California solar photovoltaic manufacturers Solyndra have even been developed with curved surfaces to take advantage of light refracted off the cool roof.4

The Lawrence Berkeley National Laboratory’s Heat Island Group is conducting research on the effects of dirt and algae on the roof surface over time, and it is working to develop an accelerated aging process. This can significantly decrease the aged testing timeline, allowing roofing manufacturers to design and improve product formulas without waiting three years for the aged performance. The Heat Island Group is also working on a self-cleaning surface for roofing materials to reduce the effects of weathering on solar reflectance values. The scientists at United Environment and Energy LLC are developing a coating that can recognize temperature changes to either reflect or absorb solar energy depending on what would be more advantageous for the building.5 The coating is created using waste cooking oil from restaurants and can be adapted to different climates with preset temperature thresholds. A team at the Massachusetts Institute of Technology has focused on a similar concept, designing a roof tile that changes colors according to temperature.6 The tiles are made of common polymers encapsulated by a clear plastic top layer and black back layer. These are just a few examples of new technologies that are pushing roofing materials to have the ability to maintain high-performance after weathering while decreasing both cooling and heating loads for a building.

Despite the benefits of cool roofing, it is still a ways off from being adopted as a standard building practice. In the U.S., it faces barriers from misconceptions, aesthetic design concerns and moisture issues caused by non-comprehensive installations. Yet, cool roofing is a simple design measure that can provide significant energy savings and environmental rewards. The Lawrence Berkeley National Laboratory’s Heat Island Group estimates that buildings with cool roofs use up to 40 percent less cooling energy than buildings with dark colored roofs.7 A designer specifying a rooftop now has several resources available to make informed and confident cool roof choices. With increasingly rigorous roofing code and program standards, and promising emerging technologies on the horizon, cool roofs are quickly becoming one of the most effective ways to save energy and help mitigate global warming.   

Cool Roof Codes and Voluntary Programs

California Title 24: Low-slope products must meet aged reflectance values of 0.55, steep-slope products must meet aged reflectance values of 0.20, heavy mass steep-slope products must meet aged reflectance values of 0.15, and all products must meet 0.75 for emittance.

ENERGY STAR program: Provides a list of products that meet a minimum solar reflectance of 0.65 for initial and 0.50 for aged low-slope roofs and an initial solar reflectance of 0.25 and aged of 0.15 for steep-slope roofs.

LEED 2009 Rating Systems for New Construction, Core and Shell, Schools, and Existing Buildings: A credit may be achieved by specifying a new or existing roof that has an initial SRI of greater or equal to 78 for low-slope roofs and 29 for steep-slope roofs.

Green Building Initiative’s Green Globes program: Offers credit for a cool roof of an SRI of 78 for low-slope and 29 for steep-slope roofs.  

Endnotes

1: Roodvoets, D., Desjarlais and W. Miller, (April 2004). Long Term Reflective Performance of Roof Membranes. RCI Annual Conference

2: The Cool Roof Rating Council. (March/April 2009) What’s So Cool About Cool Roofs? GreenSource. Web. January 6 2011. <http://continuingeducation.construction.com/article.php?L=68&C=488&P=1>

3: http://www1.eere.energy.gov/femp/pdfs/coolroofguide.pdf 

4: www.solyndra.com

5: www.sciencenews.org/view/generic/id/57485/title/Cool_roof_coating_Mechanism_kept_under_wraps

6: www.greentechmedia.com/articles/read/mit-team-invents-color-changing-roof-tiles

7: http://heatisland.lbl.gov/CoolRoofs

KEYWORDS: low slope roofing

Share This Story

Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!

Jessica Clark, LEED AP, is the marketing liaison for the Cool Roof Rating Council (CRRC). She organizes educational outreach for the program including presentations, writing and speaking engagements as well as marketing material. Clark received a B.A. in architecture from the University of California, Berkeley.
Sherry Hao is the administrative manager for the CRRC. She oversees test methods and standards development as well as educational, marketing and outreach efforts. Hao has represented the CRRC presenting at conferences throughout the world. She received her B.S. in mechanical engineering from Cornell University.

Recommended Content

JOIN TODAY
to unlock your recommendations.

Already have an account? Sign In

  • Roofing Contractor Group Publisher Jill Bloom

    Physics, the Power of Authenticity and You

    In February's Publisher's Note, Jill Bloom describes a...
    Editor's Note
    By: Jill Bloom
  • The Family Food Fare supermarket in Midland, Mich.

    ‘Rooftop Ninja’ Discovered Living on Roof, Inside Grocery Sign

    A bizarre tale out of Midland, Mich.: a woman dubbed the...
    Roofing News
    By: Bryan Gottlieb
  • A before and after heat measurement comparison

    How Hot is Too Hot in the Attic?

    If the ventilation is working, how hot should the attic...
    Sustainable Roofing
    By: Paul Scelsi
You must login or register in order to post a comment.

Report Abusive Comment

Subscribe For Free!
  • eMagazine Subscription
  • Sign Up for the eNewsletter
  • Online Registration
  • Manage My Preferences
  • Subscription Customer Service

More Videos

Sponsored Content

Sponsored Content is a special paid section where industry companies provide high quality, objective, non-commercial content around topics of interest to the Roofing Contractor audience. All Sponsored Content is supplied by the advertising company and any opinions expressed in this article are those of the author and not necessarily reflect the views of Roofing Contractor or its parent company, BNP Media. Interested in participating in our Sponsored Content section? Contact your local rep!

close
  • An overhead view of a residential block
    Sponsored byCBIZ CompuData

    From Spreadsheets to Strategy: How Roofing Companies Can Transform Financial Operations

  • Snow Guard Solutions for Metal Roofs by S-5!
    Sponsored byS-5!

    Safeguard Your Building: How Snow Guards Prevent Costly Roof & Property Damage

  • A hand holding a wooden block that reads 'EVOLVE'
    Sponsored byWatercress Financial

    Embracing Change: A New Era for the Roofing Industry

Popular Stories

QXO closed its acquisition of Beacon Building Supply on April 29, 2025.

QXO Closes Beacon Acquisition, Rebrands Immediately; Jacobs to Ring NYSE Bell

New executive orders signed by President Trump will likely further constrict an already tight labor market for the construction industry.

New Executive Orders Will Further Squeeze Labor Force

QXO CEO Brad Jacobs will share the company’s strategic vision today at the Wolfe Research Global Transportation & Industrials Conference in New York following its acquisition of Beacon Roofing Supply..

QXO’s Brad Jacobs Charts Growth at Wolfe Research Conference

Roofing Contractor Webinar

Events

December 3, 2025

The Premier Roofing Conference: Best of Success

Join roofing professionals from across the nation at the 2025 Best of Success conference, the ultimate destination for roofing professionals seeking the latest industry insights and networking opportunities. Pick up strategies for critical challenges like workforce shortage with innovative solutions, explore the latest advancements in roofing technology and sustainable practices, and gain valuable insights from industry leaders on navigating the evolving roofing landscape.

View All Submit An Event

Related Articles

  • Cool Roofing: At Home with Cool-Colored Roofs

    See More
  • Cool Roofing: Making the Case for Cool Roofs

    See More
  • Cool Roofs by the Numbers

    See More

Related Products

See More Products
  • green roofs.jpg

    Green Roofs, Facades, and Vegetative Systems 1st Edition

  • 9780128207918.jpg

    Eco-efficient Materials for Reducing Cooling Needs in Buildings and Construction 1st Edition

  • Gree_Roof_&_Construction_Ma.gif

    Green Roof Construction and Maintenance

See More Products

Events

View AllSubmit An Event
  • May 22, 2025

    Remote Teams 101: The New Way to Hire

    ON DEMAND: Our industry experts will guide you through what remote hiring and outsourcing should look like, how it can help you grow, and why it’s easier (and less scary) than you might think. If you want to save time, find great talent, and grow your business, this is one session you don’t want to miss!
View AllSubmit An Event
×

Be in the forefront of the roofing industry!

Join thousands of professionals today. Shouldn’t you know what they know?

JOIN NOW!
  • RESOURCES
    • Advertise
    • Contact Us
    • Directories
    • Store
    • Want More
  • SIGN UP TODAY
    • Create Account
    • eMagazine
    • eNewsletter
    • Customer Service
    • Manage Preferences
  • SERVICES
    • Marketing Services
    • Reprints
    • Market Research
    • List Rental
    • Survey/Respondent Access
  • STAY CONNECTED
    • LinkedIn
    • Facebook
    • Instagram
    • YouTube
    • X
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2025. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing