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20 Cool Roof Resources from the CRRC and Other Sources

July 27, 2012 Add Comment Edit

Here is a compilation of resources for anyone interested in installing a cool roof. As reviewed in previous posts, cool roofs provide many benefits and cost savings can be measured with a couple of excellent tools. Below you will find a list of resources from the Cool Roof Rating Council (CRRC) and several other sources. The CRRC is an independent, non-profit organization that maintains a third-party rating system for radiative properties of roof surfacing materials. The resources listed below offer everything you need to know about cool roofs including guidelines and information related to materials. For more detailed information on other aspects of green building and construction see the "Related Posts' section at the bottom of this post. It contains a wealth of information spanning the gamut from natural lighting to ventilation.

Benefits of Cool Roofs
Cool Roof Savings Calculators
CRRC Products Directory:
Cool Roofing Materials Database
Guidelines for Selecting Cool Roofs
To see the DOE's announcements on Cool Roofs click here.
Video glossary entry: Cool Roof
How Cool Roofs Decrease Emissions
Title 24 Blueprint Newsletter Issue # 83 on Cool Roofs
Energy Videos on the subject of Cool Roof
Learn about the ES-CRRC® Program.
Learn how to use ES-CRRC® to certify your ENERY STAR products.
AIA Cool Roof Course: The CRRC has revised its AIA Continuing Education Course. Check it out here: Cool Roofs for Hot Projects
Additional cool Roof Resources
Read the 2010 paper by Surabi Menon, Hashem Akbari, Sarith Mahanama, Igor Sednev and Ronnen Levinson, “Radiative forcing and temperature response to changes in urban albedos and associated CO₂ offsets”
Read the 2008 paper by Hashem Akbari, Surabi Menon and Art Rosenfeld, “Global cooling: increasing world-wide urban albedos to offset CO₂” here.
CRRC Website,
CRRC Twitter @Cool_Roofs,
CRRC on Facebook,
CRRC LinkedIn

© 2012, Richard Matthews. All rights reserved.

Related Posts
The Effectiveness of Cool Roofs in Hot and Cold Climates
The Benefits of Cool Roofs
Cool Roof Savings Calculators
Three Types of Cool Roofs
Green Buildings Offer Many Benefits
The Extraordinary Growth of Green Building
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Green Building Environmental Benefits
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Green Buildings Health and Performance Benefits Part 1
Green Buildings Health and Performance Benefits Part 2
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Green Buildings: The Many Benefits of Ventilation
The Future of Green School Buildings
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Cool Roofs Savings Calculators

July 26, 2012 2 Comments Edit

A cool roof is a way of reducing the costs associated with air conditioning and this reduces energy usage which in turn reduces emissions. Estimates for cost savings associated with cool roofs run between 10 and 25 percent. There are a number of tools to help people evaluate the cost savings resulting from the installation of cools roofs. Below you will find two such tools, one from the US Department of Energy's Oak Ridge National Laboratory deals and the other developed by Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory.

1. DOE Cool Roof Calculator

This tool developed by U.S. Department of Energy's Oak Ridge National Laboratory estimates cooling and heating savings for low slope roof applications with non-black surfaces.

2. Roofing Comparison Calculator (RSC)

This tool was developed by Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory in order to provide industry-consensus roof savings for both residential and commercial buildings. It reports the net annual energy savings (cooling energy savings minus heating penalties) and thus is only applicable to the buildings with a heating and/or cooling system.

© 2012, Richard Matthews. All rights reserved.

Related Posts
The Effectiveness of Cool Roofs in Hot and Cold Climates
The Benefits of Cool Roofs
20 Cool Roof Resources from the CRRC and Other Sources
Three Types of Cool Roofs
Green Buildings Offer Many Benefits
The Extraordinary Growth of Green Building
The Implications of the Growth of Green Buildings
Green Building Environmental Benefits
Green Building Economic Benefits
Green Building Social Benefits
Green Buildings Resouces
Green Buildings Combat Climate Change
Green Buildings Health and Performance Benefits Part 1
Green Buildings Health and Performance Benefits Part 2
Green Buildings: The Many Benefits of Natural Lighting
Green Buildings: The Many Benefits of Ventilation
The Future of Green School Buildings
Top 10 Green Building Trends for 2010
25 Blogs Leading the Sustainable Building Revolution

Three Types of Cool Roofs

July 25, 2012 1 Comment Edit

Cool roofs fall into one of three categories: roofs made from inherently cool roofing materials, roofs made of materials that have been coated with a solar reflective coating, or green planted roofs. While green roofs are in many ways the best, they are also the most difficult to construct and maintain. Inherently cool roofs like vinyl are relatively easy to install, while the easiest and in this respect the best cool roof is a coated roof.

Inherently cool roofs

White vinyl roofs, which are inherently reflective, achieve some of the highest reflectance and emittance measurements of which roofing materials are capable. A roof made of thermoplastic white vinyl, for example, can reflect 80 percent or more of the sun’s rays and emit at least 70% of the solar radiation that the building absorbs. An asphalt roof only reflects between 6 and 26% of solar radiation, resulting in greater heat transfer to the building interior and greater demand for air conditioning.

Coated roofs

An existing (or new) roof can be made reflective by applying a solar reflective coating to its surface. The reflectivity and emissivity ratings for over 1000 reflective roof products can be found in the CRRC (Cool Roofs Rating Council) website.

Green roofs

Green roofs provide a thermal mass layer which helps reducing the flow of heat into a building. The solar reflectance of green roofs varies depending on the plant types (generally 0.3-0.5).Because of the lower solar reflectance, green roofs reflect less sunlight and absorb more solar heat than white roofs. The absorbed heat in the green roofs is trapped by the greenhouse effect and then cooled by evapotranspiration.

© 2012, Richard Matthews. All rights reserved.

Related Posts
The Effectiveness of Cool Roofs in Hot and Cold Climates
The Benefits of Cool Roofs
20 Cool Roof Resources from the CRRC and Other Sources
Cool Roof Savings Calculators
Green Buildings Offer Many Benefits
The Extraordinary Growth of Green Building
The Implications of the Growth of Green Buildings
Green Building Environmental Benefits
Green Building Economic Benefits
Green Building Social Benefits
Green Buildings Resouces
Green Buildings Combat Climate Change
Green Buildings Health and Performance Benefits Part 1
Green Buildings Health and Performance Benefits Part 2
Green Buildings: The Many Benefits of Natural Lighting
Green Buildings: The Many Benefits of Ventilation
The Future of Green School Buildings
Top 10 Green Building Trends for 2010
25 Blogs Leading the Sustainable Building Revolution

The Benefits of Cool Roofs

July 25, 2012 Add Comment Edit

Cool roofs offer energy savings and global warming mitigation. In its simplest essence, Cool roofs offer high solar reflectance. This is achieved primarily by reflecting the visible, infrared and ultraviolet wavelengths of the sun, which in turn reduces heat transfer to the building. Cool roofs are also are high in thermal emittance (the ability to radiate absorbed, or non-reflected solar energy). Cool roofs can reportedly save up to 15% off the annual air-conditioning energy use in a single-story building.

Most of the sunlight that falls on a white roof much of is reflected and passes back into space. But when sunlight falls on a dark roof most of it is absorbed and converted into much longer wavelengths which we know as heat. The atmosphere is transparent to sunlight but opaque to heat, which is why white roofs help cool the planet and dark roofs warm the planet.

Most of the roofs in the world (including over 90% of the roofs in the United States) are dark-colored. In the heat of the full sun, the surface of a black roof can increase in temperature as much as 50 °C (126 °F), reaching temperatures of 70 to 90 °C (158 to 194 °F). White surfaces reflect more than half of the radiation that reaches them, while black surfaces absorb almost all.

A 1,000-square-foot (93 m²) white roof will offset 10 tons of carbon dioxide over its 20 year lifetime. The potential reduction is GHGs is very significant. If all urban, flat roofs in warm climates were whitened, the resulting 10% increase in global reflectivity would offset the warming effect of 24 Gigatonnes of greenhouse gas emissions, or equivalent to taking 300 million cars off the road for 20 years.

A 2012 study by researchers at Concordia University estimated that worldwide deployment of cool roofs and pavements in cities would generate a global cooling effect equivalent to offsetting up to 150 Gigatonnes of carbon dioxide emissions - enough to take every car in the world off the road for 50 years.

Cool roofs have a wide range of benefits including:

Improved energy efficiency
Reduced greenhouse gas emissions
Reduction in urban heat island effect and smog
Improved occupant comfort (Less heat)
Reduced cooling energy load
Save peak electricity demand costs if you have time-of-use metering.
Extended roof life service life and help
Reduce roofing waste added to landfills.
Comply with codes and green building programs (like Title 24 Energy Efficiency Building Standards)

Reduced building heat-gain, as a white or reflective roof typically increases only 5–14 °C (10–25 °F) above ambient temperature during the day. Research shows that conventional (black) roof membranes degrade from the sun adversely impacting durability. High temperatures and large temperature variations are also detrimental to the longevity of roof membranes. Reducing the extremes of temperature change will reduce the incidence of damage to membrane systems. Covering membranes with materials that reflect ultraviolet and infrared radiation will reduce damage caused by u/v and heat degradation.

White or white coated roofing membranes, or white gravel are best but Cool roofs can come in many colors, even some dark colors are EnergyStar rated, but white is the most reflective.

One contested study by researchers at Stanford University suggested that although reflective roofs decrease temperatures in buildings and mitigate the urban heat island effect, they may actually increase global temperature. However, according to a 2008 case study in the Province of Almeria, Southern Spain, cool roofs reduced the ambient temperature by 1.6ºC over a period of 20 years compared to surrounding regions.

© 2012, Richard Matthews. All rights reserved.

Related Posts
The Effectiveness of Cool Roofs in Hot and Cold Climates
20 Cool Roof Resources from the CRRC and Other Sources
Cool Roof Savings Calculators
Three Types of Cool Roofs
Green Buildings Offer Many Benefits
The Extraordinary Growth of Green Building
The Implications of the Growth of Green Buildings
Green Building Environmental Benefits
Green Building Economic Benefits
Green Building Social Benefits
Green Buildings Resouces
Green Buildings Combat Climate Change
Green Buildings Health and Performance Benefits Part 1
Green Buildings Health and Performance Benefits Part 2
Green Buildings: The Many Benefits of Natural Lighting
Green Buildings: The Many Benefits of Ventilation
The Future of Green School Buildings
Top 10 Green Building Trends for 2010
25 Blogs Leading the Sustainable Building Revolution