COOL Roofing Shingles
A roof plays a critical role for your home. It helps protect it from the elements and impacts its overall exterior look and curb appeal. Further, an asphalt shingle roof can potentially deliver energy-saving benefits when “COOL” asphalt shingles are installed.
These shingles are engineered to have higher solar reflectance and thermal emittance properties that can help reduce a home’s cooling load on hot, sunny days. We’ve rounded up a few of our experts to help explain why choosing COOL asphalt roofing shingles, even if not required, can have potential energy-saving benefits for your home.
Your Roof and the Sun
First things first, let’s understand how a roof reacts to heat from the sun, and the impact this relationship has on the temperature inside your home – and therefore on your energy bills.
Three main things happen when the sun’s radiation hits the surface of an asphalt shingle roof:
- Absorption: Some level of heat is absorbed by the roof and transferred into the home.
- Solar Reflectance: The roof reflects a portion of the sun’s energy. Shingles with a higher solar reflectance allow less heat to transfer into a home.
- Thermal Emittance: The roof radiates some of the absorbed heat back into the atmosphere. Shingles with a higher thermal emittance also allow less heat to transfer into a home.
If your attic is not properly ventilated and insulated, this absorbed heat may increase the temperature inside your home. This could contribute to increased energy costs, as you may need to run cooling devices or central air systems more often or at lower temperatures to keep the inside of your home feeling comfortable.
If you notice that your energy bills are getting higher, you may want to have a roofing contractor come out to inspect your roof and attic for proper ventilation and insulation.
As the sun shines on your roof, it delivers visible and invisible (infrared and ultraviolet) light waves. What your roof does with reflecting the sunlight determines its solar reflectance. The more waves that are bounced back into the atmosphere, the higher the solar reflectance of the asphalt roofing shingle.
The solar reflectance measurement ranges between 0.0 and 1.0, with 1.0 representing 100% reflectance with no absorption. Asphalt shingles with higher solar reflectance values can achieve ENERGY STAR certification. These shingles are considered “COOL” products in the asphalt shingle industry.
Asphalt shingles must meet the following two specifications to qualify for ENERGY STAR certification:
- An initial solar reflectance of at least 0.25
- Three-year solar reflectance measurement of at least 0.15
Note: these requirements alone do not ensure compliance with Energy Codes.
As your roof absorbs solar radiation, it begins to heat up. Some of this radiated heat is dispersed into the surrounding atmosphere. This process of radiating previously absorbed heat is thermal emittance.
Thermal emittance measurement ranges between 0.0 and 1.0 (sometimes referred to as a percentage between 0 and 100). The higher the number, the less heat transferred to the home.
Although ENERGY STAR doesn’t require a thermal emittance value for certified asphalt shingles, the measurement is often listed on specification sheets to better inform consumers. When choosing products based on high or low thermal emittance, keep in mind your climate. Materials with a high thermal emittance may be a better choice for hot, sunny regions while those with a low thermal emittance may help homes lower the heating load in severely cold climates.
A Final Key Measurement: The Solar Reflectance Index (SRI)
The Solar Reflectance Index, or SRI, is a calculation using the aged solar reflectance and thermal emittance measurements of the asphalt shingles materials. It ranges from 0 to 100.
This measurement can be used as an indicator of how hot shingles are likely to become when they’re exposed to the sun. The lower the SRI value, the hotter the asphalt shingles are likely to be in sunlight. Conversely, roofing shingles with a higher SRI will help reduce the cooling load on your home.
In many cases, asphalt shingle manufacturers use a shingles third-party certified aged SRI value to demonstrate compliance with cool roof energy codes.
What Are COOL Roofing Shingles?
COOL roofing shingles use solar-reflecting granules to help decrease the amount of heat transferred into your home. This not only helps keep interior areas cooler, but it also reduces the strain on any home cooling devices.
In addition to helping to keep your home more energy-efficient, COOL roofing shingles may also benefit the environment:
- The EPA is researching how to reduce the radiant atmospheric heat that accumulates in cities and among groups of buildings, also known as urban heat islands, with COOL roofing materials.
- Comfortable interior temperatures lessen the need for electrical-fed cooling devices, like fans, air conditioners, and heat pumps, especially during peak use. This can significantly affect commercial customers who may pay additional fees for peak power.
- Less electrical usage leads to less power plant emissions, such as carbon and sulfur dioxides.
For an asphalt roofing shingle to be classified as a “COOL” under the energy codes, it needs to have a Cool Roof Rating Council (CRRC) rating for thermal emittance and solar reflectance. It also must meet the specific solar reflectance, thermal emittance and/or solar reflectance index values defined by the specific energy code.
COOL roofing shingles are specially designed with solar-reflecting granules (granules that reflect the sun’s rays) to help decrease the amount of heat transferred into a home. These shingles can help make your home more comfortable and may even be required if you live in certain geographical areas. For residential homes, COOL roofing shingle use is most prevalent in California. Read more about how to meet cool roofing code requirements in California.
In addition to installing COOL roofing shingles, proper levels of attic insulation can also have a large impact on energy cost savings.
COOL Roof Shingle Colors
Typically, COOL asphalt roofing shingles run toward the lighter hues:
- Light gray
- Light tan
Many lighter tone products available throughout the U.S are designated with an “ENERGY STAR” label. In California, homeowners have access to darker asphalt shingles that meet various COOL roof energy codes that are specific to the state. The SRI values for darker COOL asphalt shingles will usually be slightly lower than the lighter tones, but the darker COOL shingle values are still high enough to meet most of the California energy code requirements.
COOL Roofing Review
- Even if not required by energy codes, COOL asphalt roofing shingles may lower the cooling load on a home in hot climates. This may increase your home’s energy efficiency and help the environment.
- Cool asphalt roofing shingles are characterized by 3 key values: solar reflectance, thermal emittance, and solar reflectance index (SRI).
- In many cases, asphalt roofing shingle manufacturers use a shingle’s third-party certified aged SRI value to demonstrate compliance with cool roof energy codes. This practice is prevalent in California.
- Asphalt roofing shingles with higher SRI ratings are “cooler” in the sunshine. Higher SRI ratings for shingles mean greater reduction in cooling load on a home.
- Asphalt shingle products with an “ENERGY STAR” rating do not utilize the SRI compliance path. These shingles must have an initial solar reflectance of at least 0.25 and a three-year solar reflectance measurement of at least 0.15.
- Owens Corning asphalt shingle products labeled as “COOL” are rated with the Cool Roofing Rating Council (CCRC) for solar reflectance and thermal emittance. This is a requirement in some energy codes.
- In most of the U.S., “COOL” asphalt shingles are available in lighter colors (white, light gray, light tan, etc.). In California, darker color tones are available.
Start Your COOL Roofing Project Today with Owens Corning COOL Asphalt Roofing Shingles
Ready to take the next step towards building an energy-efficient home? Whether you’re embarking on a reroofing project or adding the finishing touches on your newly constructed house, Owens Corning Roofing can help.
Owens Corning COOL asphalt roofing shingles meet various levels of COOL roofing requirements and are available in a great selection of colors that complement many homes exteriors*. Don’t forget to take advantage of the many state-specific incentive programs for home and business owners who use COOL roofing materials.
* “Cool” product availability varies by region. Duration® Premium COOL Shingles are available nationally in four colors. Shasta White shingles in Owens Corning’s Supreme®, Oakridge® and TruDefinition® Duration® shingle lines are available in most markets. Darker “COOL” colors are available only in California.