Roofs By The Numbers

Homeowners who are researching a new roof or skylight may be flooded by a sea of numbers relating to thermal emittance, solar gain coefficients and U-factors. A trusted, professional Monmouth County roofing contractor is the best resource for explaining how these values help homeowners select a roof, but it helps to have a little understanding before talking to a roofer.

Many of these terms and ratings relate to how well a roof saves energy. In addition, one of the biggest trends in energy-efficient roofing focuses on cool roof technology. The Department of Energy estimates that a cool roof can reduce a home’s air conditioning demand by 10 to 15 percent and save as much as 50 cents per square foot by lowering the roof temperature. To help consumers find the cool roof that best suits their home and budget, roof shingles receive an energy rating that reflect the product’s efficiency.

First, roofing products that are energy efficient carry the Energy Star label certified by the Cool Roof Rating Council, or CRRC. The CRRC also labels roof products with the Solar Reflectance Index. The index demonstrates how much solar energy is reflected back by the roof as well as how much heat the roof absorbs and then emits into the atmosphere. In general, the higher the SRI number, the cooler the roof and home.

The important ratings for skylights are more complex. Skylights with high-energy performance also carry the Energy Star label, but five additional ratings are listed on a skylight’s label.

The National Fenestration Rating Council coordinates the label ratings but doesn’t set minimum standards for efficiency. As a result, it’s helpful to know what the numbers mean so consumers can choose the best skylights for their homes.

Two skylight ratings relate directly to energy efficiency: U-factor and Solar Heat Gain Coefficient, or SHGC. U-Factor demonstrates the skylight’s insulating ability by measuring heat transfer; a skylight with a lower U-factor is more efficient. SHGC, on the other hand, reflects how well the skylight filters solar heat on a scale of 0 to 1. The lower the SHGC number, the more heat is blocked by the skylight.

The other three ratings consumers see on a skylight label indicate other performance measures. Visible Transmittance, or VT, demonstrates how much light is allowed through on a scale of 0 to 1, with higher numbers translating into more light. Air Leakage, or AL, reveals how much air flows through the window’s joints, with the lower values reflecting less air leakage. The final rating measures the window’s resistance to water build-up, or Condensation Resistance. It is measured from 0 to 100, with higher numbers indicating less water build-up.

Ultimately, choosing a product that is more energy efficient saves money and the environment. To find out how much money can be saved with an efficient roof, consumers can check out the roof savings calculator at Have a question regarding new roofs or roof repairs? Ask the roofers from Fortified Roofing of Monmouth County NJ.

Roofing term courtesy of Fortified Roofing, Monmouth County NJ:

Solar Reflectance Index

The Solar Reflectance Index is a metric of solar reflectance and thermal emittance, as determined by the Cool Roof Ratings Council. Roofs with higher SRI values are considered cooler and more efficient because they absorb less heat into the home.

Monmouth County NJ roofing FAQ

How much money can a homeowner save with a cool or energy-efficient roof?

Although cost savings depend on the type of roof selected, the size of the home, the local price of utilities and the location of the home, consumers can expect to save up to 20 percent on cooling costs. For some areas, that savings can amount to about 50 cents per square foot of interior space. Many state governments and local utility companies also offer tax rebates for installing energy-efficient roofing or skylights.

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If you would like to ask a question regarding roofers, a new roof installation, roof leak repairs, skylight options or gutters and downspouts please contact Fortified Roofing today!

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