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U.S. Department of Energy Quietly Raises Insulation Standards

2/1/2010 4:42:00 PM

Tags: Dan Chiras, insulation standards, ceiling insulation

For years, the U.S. Department of Energy (DOE) has recommended R-30 and R-38 insulation for ceilings in U.S. homes, depending on the climate and the source of heat. Generally, the colder the climate, the more insulation they recommended.

DOE also recommended higher levels of ceiling insulation in homes heated with electric heat, which is of course the least efficient and hence the most expensive way to heat a home. Even so, DOE never recommended more than R-38 — even in the coldest climates.

Despite DOE’s long-standing guidelines, many of us who are interested in building super-efficient homes have been recommending to our clients, including architects and builders, that they install much higher levels of ceiling insulation — R-50 to R-60 in most climate zones. In really cold climates like that of North Dakota and northern Idaho we’ve been recommending even higher levels — from R-70 to R-80.

Many conventional architects and builders I’ve spoken to over the years have viewed such recommendations skeptically, and for good reason. One reason is that they, like all the rest of us, have been told that there’s a point at which additional insulation results in diminished returns. Why spend more money for marginal returns?

What architects and builders haven’t been told is that some forms of insulation lose their R-value over time. R-value decreases, for example, if a loose-fill insulation settles. In addition, tiny amounts of moisture accumulation can dramatically lower the R-value of many forms of insulation. Architects and builders haven’t been told — and haven’t come to this realization on their own — that the point of diminishing returns shifts upward as energy prices increase.

North America has been blessed for many years with inexpensive energy. Those days are over and energy prices are only bound to increase.
Bottom line, then, rising energy costs dramatically shift the economics of insulation. The old rules no longer apply. Fortunately, many enlightened architects and builders are beginning to adjust their practices to reflect this new reality. Even the DOE has increased its recommendations as you can see from the table below and in this link to their insulation recommendations.

Recommended R Values 

Contributing editor Dan Chiras is a renewable energy and green homes expert who has spent a lifetime learning life’s lessons, which he shares in his popular blog, Dan Chiras on Loving Life. He’s the founder and director of The Evergreen Institute and president of Sustainable Systems Design. Contact him by visiting his website or finding him on .

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NinaCamille C.
2/23/2011 11:30:59 PM
Standards for proper regulation. Renewable energy companies have been getting help through Congress for the last few years. The has been administering helpful programs. Through funding committed through the American Recovery and Reinvestment Act, the Department of Energy guaranteed green-power companies' loans. The fact that not all of these corporations succeeded has some Congress people worried. An investigation has been opened to see if the funds were used correctly.

hugh owens_2
2/6/2010 11:07:29 AM
Unless you have an attic ceiling, It would be very difficult to get to R70-80 with any known insulation. Even spray polyurethane which I use in our frigid climate in WY will only get me to 45-50 after the urethane ages using 10"(9+)rafters. I abhor truss rafters for a variety of reasons. Going to 12" (actual 11.25") will only give you 55-60. Urethane can start life at as high as R-6 but ages to R-5 according to my suppliers. A 2X6 wall will then be 25-28 at best with foam(19-21 with f-glass) unless you add foam sheeting outside the studs. The other option is a double wall or going to 2X8 or 2X10 walls. This is Very expensive. What other methods are available?

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