06/01/2008

Understanding the R- and U-Values of Insulation

Learn how these standardized rating systems ensure consistency in energy performance

 
Understanding the R- and U-Values of Insulation

Getting More for Your Insulation Investment
Visit these websites for more information on finding the right insulation for your needs, and for information about tax incentives and rebates.

  • To read about benchmarking, visit the site of the Commercial Buildings Energy Consumption Survey (CBECS), which collects information on U.S. commercial buildings, their energy-related characteristics, and their energy consumption and expenditures.

  • To read about software modeling, visit the site of the Energy-Wise Roof Calculator, an interactive software application with a graphical method for constructing roof assemblies that evaluates thermal efficiency and estimates energy costs.

  • To read about tax incentives, visit the website of the Tax Incentives Assistance Project (TIAP), which provides information about federal income tax incentives for energy-efficient products and technologies. Or, visit the Database of State Incentives for Renewables & Efficiency site, which features information on state, local, utility, and federal incentives that promote renewable energy and energy efficiency.

Improved insulation is a good step toward improving building efficiency, particularly since the Atlanta-based American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) increased minimum roof-insulation levels in 2007 in its Standard 90.1—the first increase in 18 years. And, if that isn't enough to spur someone into action: A recent McKinsey & Co. report named insulation as the single most cost-effective way to improve energy efficiency based on cost comparison per square foot.

A standardized insulation rating system ensures consistency, with insulating materials rated in R- and U-values. R-values represent resistance to the flow of heat; the higher the R-value, the greater the resistance and the insulating value. U-values are the direct opposite, representing the amount of heat that escapes through a material. The lower the U-value, the slower the rate of heat flow and the better the insulating quality.

Ultimately selecting which product and value to use depends on many factors - particularly thermal load; regardless, ASHRAE's new above-deck roof insulation standard is a good place to start, as it jumped 33 percent, from R-15 to R-20, in five of six climatic regions. "This standard is not a requirement to retrofit—it's a guideline—but it can become one if a state adopts it as a building code," explains Jeff Harris, vice president for programs at the Alliance to Save Energy, Washington, D.C. "Standards should be considered for new builds and major renovations—any time you have a reasonable opportunity to add insulation, you should."

Still, that doesn't necessarily mean that more insulation is better. Although R-value is proportional to insulation thickness, it also depends on the type of material and its density. The more air pockets in an insulating product, the higher the R-value.

"Glass façades are the perfect example of aesthetics colliding with physics," explains Paul Bertram, director of environment and sustainability for the North American Insulation Manufacturers Association, Alexandria, VA. "You can attain efficiencies, but there are tradeoffs. Regardless of a building's design, the answer isn't stuffing in as much insulation as you can; you'll reach a point of diminishing return. Coordination between all building systems is a leading indicator of energy efficiency, and optimizing that integration can best be achieved when architects and engineers work as a team. Proper installation is also as important as the product you're using."

Rated R-Value and Thickness of Insulation*

R-Value

 R6 R11R13R15R19R21 R22R25R30 (C**) R30  R38 (C**)R38 

Insulation Thickness

 1.75" 2.5" 3.5" 3.5" 3.5" 6.25" 5.5" 6.5" 8" 8.5" 10" 10" 12"

* All listed thicknesses are approximate and may vary by +/- 0.5 inches.

** The "C" denotes high-density materials specifically designed for installation in areas where space is limited, such as cathedral ceilings.

Stephanie J. Oppenheimer, former assistant vice president of communications at BOMA Intl., is principal at Skylite Communications, based in Falls Church, VA.

 


Visit our website today to learn about the design flexibility of a Morton building and the endless possibilities of partnering with our designBUILD team.


Wood construction is both cost and energy efficient. Check out Morton Buildings and our designBUILD team online today to discover all the benefits of post-frame construction.


When choosing a metal-clad building for your next construction project, consider Morton Buildings, Inc., and their designBUILD team, we’ll make your dream a reality.

Bluebeam® Revu® simplifies digital facilities document management from design review to leveraging as-builts, maintenance manuals and O&Ms submittals.

We Can Help You Reduce Energy by 30%

Our mission is to help our customers manage their buildings' energy costs, improve reliability, and enhance performance while having a positive impact on the environment.
CLICK HERE to find out how.


Visit our website today to learn about the design flexibility of a Morton building and the endless possibilities of partnering with our designBUILD team.


Wood construction is both cost and energy efficient. Check out Morton Buildings and our designBUILD team online today to discover all the benefits of post-frame construction.


When choosing a metal-clad building for your next construction project, consider Morton Buildings, Inc., and their designBUILD team, we’ll make your dream a reality.

Bluebeam® Revu® simplifies digital facilities document management from design review to leveraging as-builts, maintenance manuals and O&Ms submittals.

We Can Help You Reduce Energy by 30%

Our mission is to help our customers manage their buildings' energy costs, improve reliability, and enhance performance while having a positive impact on the environment.
CLICK HERE to find out how.


 
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