How to keep your new attic from being an energy-efficiency drain
(ARA) - The attic accounts for a tremendous amount of lost energy. This space can reach up to 165 degrees in summer months. When this heat makes its way into the rest of the building, energy efficiency drops and cooling costs rise. While building a new home, a radiant barrier is a proactive solution to energy loss, reducing monthly cooling costs in the process.
Consider adding a radiant barrier
Radiant barriers can help reduce summer heat gain and hold in heat during the winter months. An independent study in 2010 by ConSol indicated that radiant barrier sheathing is one of the top three energy-efficient technologies in new home construction in terms of performance, cost and return on investment.
The U.S. Department of Energy recognizes radiant barriers as a way to lower cooling energy usage during the summer. Correctly installed, the foil surface of the radiant barrier sheathing can block up to 97 percent of the radiant heat in the roof panel from entering your attic. This can lower the attic temperature by as much as 30 degrees and reduce cooling costs by up to 17 percent. A cooler attic will benefit your attic-installed air handling system and in some cases reduce the tonnage required in an HVAC system.
A year-long study performed by SGS U.S. Testing Company in the foothills of North Carolina of two side-by-side structures with and without radiant barrier sheathing shows that a radiant barrier can also help prevent attic heat loss during the winter, reducing energy costs by up to 5 percent. So no matter what time of year, a radiant barrier can help you save.
How to choose the right radiant barrier
When building a new home, talk to your contractor about adding a radiant barrier into your roof system. There are a number of radiant barriers available, but not all of these products are the same. One critical factor to keep in mind is how quickly the radiant barrier dries from potential moisture during the construction process.
In order to make sure your contractor is using a radiant barrier that has been manufactured to help prevent moisture issues, it's important to understand just how a radiant barrier is made. Radiant barrier sheathing typically consists of a structural OSB (oriented strand board) panel with a layer of aluminum adhered to the surface. Some radiant barrier panel manufacturers purchase foil materials that come pre-perforated. This may not necessarily allow the panel to breathe, because the perforations do not extend into the wood fiber of the panel. An added challenge is that the adhesive used to apply the radiant barrier to the substrate can fill in the perforations, decreasing the ability of moisture in the panel to escape.
One product on the market, LP(R) TechShield(R) Radiant Barrier Sheathing, addresses the issue of moisture through the use of the patented VaporVents(TM) technology. This product features incisions that penetrate past the foil and glue and into the wood fiber, allowing the panels to breathe and moisture to escape.
"Tests show that VaporVents technology allows the panel to dry almost as efficiently as OSB sheathing without a radiant barrier, while other products that use pre-perforated foil showed a significant amount of moisture, in some cases more than 30 percent, still in the panel after 80 days of drying. Wood needs to stay under 19 percent moisture to avoid structural issues," says David Drew, OSB technical sales manager for LP Building Products.
Understanding the options
In an effort to reduce attic temperatures, your builder may recommend spray-foam insulation to seal the attic and create conditioned space for the HVAC equipment. While this can be an effective method with the right amount of foam, it can also be costly.
"Oakridge National Laboratory recently released a study showing that a roof system composed of cool roof shingles and radiant barrier roof sheathing can provide the same efficiency as a roof-applied spray-foam insulated attic at a substantially lower cost," Drew says.
When building a new home, a radiant barrier is an effective, smart way to achieve greater energy efficiency. However, not all radiant barrier products are created equal. Choosing the right radiant barrier brand can help protect against future hassles and costs associated with moisture damage.