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.

Absorbing Heat

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.

Solar Reflectance

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.

Thermal Emittance

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.

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.

Contact Us Today

The next time you’re searching for roofing companies near me, roofing contractors near me or roofing contractors ct, or roof replacement near me look no further then BP Builders. We would be happy to fix the problem. Call us now or fill out the form on this page. BP Builders is a full-service company offering complete roofing, siding and gutter replacement services. For prompt, friendly and professional help, please contact us today!