The R-Value Myth

Just about every project that I come across, at some point in time, I am asked what the "R-Value" of a structural insulated panel is. The answer that is given is based on testing data that is accurate based on the structure of the test, but there is so much left to the proverbial "reading between the lines" that it is hard for an average consumer to decipher between accurate data and marketing fluff.

I have found two resources that I would like to share with you. The first is a book written by David B. South entitled "The "R" Fairy Tale, The Myth of Insulation Values". In chapter 4 of his book, Mr. South writes,

"The R-value is a modern fairy tale. It's a fairy tale that has been so touted to the American consumer that it now has a chiseled in-stone status. But the saddest part of this fairy tale is that the R-value by itself is almost a worthless number. It is impossible to define an insulation with a single number. To do so, we must know more. So why do we allow the R-value fairy tale to perpetuate? I don't know. I don't know if anybody knows. What we do know is that the R-value fairy tale obviously favors fiber insulation. Consider the R-value of an insulation after it has been submersed in water or as a 20 mile-per-hour wind blows through it. In either of these scenarios, the R-value of fiber insulation goes to zero. But those same conditions barely affect solid insulations. That's why I believe that R-value numbers are misleading, meaningless numbers unless we know other characteristics."
Further in the chapter, Mr. South eludes to the benefits of an airtight structure and the benefits of hardboard insulation. He writes:
"The test used to produce the k-value is an ASTM (American Society for Testing and Materials) test. This ASTM test was designed by a committee to give us measurement values that -- they hoped -- would be meaningful. Unfortunately, the test was designed with a flaw or bias. Because of the way it's designed, the test favors fiber insulations: fiberglass, rock wool and cellulose fiber. Very little input went into the test for solid insulations, such as foam glass, cork, expanded polystyrene or urethane foam. Nor does the test account for air movement (wind) or any amount of moisture (water vapor). In other words, the test used to create the R-value is a test in non-real-world conditions. For instance, fiberglass is generally assigned an R-value of approximately 3.5. It will only achieve that R-value if tested in an absolute zero wind and zero moisture environment. Zero wind and zero moisture are not real-world. Our houses leak air, all our buildings leak air, and they often leak water. Water vapor from the atmosphere, showers, cooking, breathing, etc. constantly moves back and forth through walls and ceilings. If an attic is not properly ventilated, water vapor from inside a house will very quickly semi-saturate the insulation above the ceilings. Even small amounts of moisture will cause a dramatic drop in a fiber insulation's R-value — as much as 50 percent or more."

The second resource I'd like to share with you is a website created by Randy L. Martin. His site, www.coloradoenergy.org, was designed to be the place to start when looking for energy efficiency or renewable energy information for Colorado. This all inclusive web site will point you to energy efficiency or renewable energy organizations or companies within the state of Colorado. It will also provide you with information you need to make your home or business more energy efficient.

For an list of independantly tested R-values of materials (and remember to go further than this), check out. http://coloradoenergy.org/procorner/stuff/r-values.htm

The point is that there is more to an energy efficient structure than just how well the insulation tested in a perfectly controlled environment. Today's consumers are becoming more educated about energy efficient construction methods. Those businesses (architects & construction firms) that are not building "the same ol' way because that's what they've done for years" are seeing explosive growth in a down construction market.