Cool Roof Resources

There are thousands of product options just for cool roofing (including Conklin), so 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 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. 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. 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 offers savings estimates for small- and medium-sized facilities with flat roofs.
• The EPA Roof Savings Calculator 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.

Look for a Conklin Roofing Systems contractor in your area:

ROOFING CONTRACTORS NEEDED IN MULTIPLE STATES!

Patton Services | (309) 303-3128 | rpatton55@comcast.net | http://www.whiteroofingsystems.com

Classifying Roof Coatings by Binder & Carrier Type

Reflective roof coatings are available for a variety of roofing systems, including low- and steep-slope metal and bituminous systems. You can specify various coatings for different types of low-slope roof systems, and manufacturers like Conklin are introducing new formulas to keep up with changing needs and roofing materials.

Water-based urethanes, bio-based materials, 100% solids silicones, and low volatile-organic-compound asphalt cutbacks are in the pipeline. Self–cross-linking, water-based coatings; faster-setting, water-based coatings; and a basecoat primer suitable for every roofing membrane also are on the horizon.

Manufacturers like Conklin commonly classify roof coatings according to binder type and carrier type, which also determine application methods and compatibility with existing roof surfaces.

A coating’s binder, or resin, is its basic matrix material, which adheres to a roof surface. Manufacturers use different binder chemistries to meet price and performance criteria and to match specific roof substrates. The binder type dictates most of a coating’s primary physical properties, including elongation, tensile strength, adhesion to a substrate material, permeance, water swelling, and low-temperature flexibility.

Roof coating binders typically range from asphalts to a variety of elastomers — acrylics, urethanes, silicones, thermoset rubbers and various block polymers — as well as blends of these materials.

A coating’s carrier is the liquid that combines with the binder to reduce viscosity to a workable level. The carrier generally evaporates during curing.

The carrier also generally dictates a coating’s installation process and cure time. Manufacturers like Conklin now more often use water as a carrier, in which case the binder is suspended in water as an emulsion. Traditionally, most coating binders have used a solvent as the carrier. Solvent-based coatings cure in a broader range of weather conditions and might be the best choice — or only choice — in freezing or wet conditions.

A coating’s cure rate varies greatly because it reacts to ambient humidity, temperature and sunlight. This reaction is especially true of water-based coatings. Coating installers must allow coatings to cure sufficiently to ensure they are waterproof.

Finally, manufacturers like Conklin add pigments and fibers to binders to control physical properties and increase reflectivity. Because reflectivity and emittance are defining properties of cool roofs, organizations such as the Energy Star program and the Cool Roof Rating Council in California monitor and measure these coatings.

Please also see the March 2009 facilitiesnet.com article by Reed Hitchcock titled "Manufacturers Classify Coatings by Binder and Carrier Type"


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ROOFING CONTRACTORS NEEDED IN MULTIPLE STATES!
Patton Services | (309) 303-3128 | rpatton55@comcast.net | http://www.whiteroofingsystems.com/