R Value

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How Valuable is this Performance Indicator? There is a widespread belief in the general public that all insulation materials of equal R-value will perform equally.

major missing factors are air seal, performance curve over time, and even the parameters of the test. Example: the test is conducted at 75 degrees F ambient temperature. Why 75 degrees? Well, we think it is because materials competing with foam perform as well as foam. You'd get very different results at the extreme ranges (say 105 degrees F or 40 or 20 degrees F. The foam maintains its performance while the materials of some of the leading materials degrade substantially.

How about another fact of life such as wind and pressure differentials between indoors and outdoors? The r-value method simply ignores that. To continue on our conspiracy theory, perhaps it was left out because our competition offers no effective air seal.

Our favorite example is the styrofoam coffee cup. Despite a very low R- value of only 0.5, everybody knows how well this cup insulates. How about a test like this: put fiberglass in your hand, and even offer an advantage over the styrofoam cup. Let's use R-13 of fiberglass, and pour the boiling coffee over it. The result: the hand is burnt. Since fiberglass does not provide a seal, this is an unfair comparison. Or is it? Our view: the air seal is integral part of performing insulation. Accordingly, forget R-value, and ask the officials setting these standards to come with a test method with some relevance to the real world out there. Shall we call this I-value for "insulation value?" Here is the fact: in many studies, it has been shown that homes insulated with foam usually need about 50% less energy compared with a home properly insulated with the standard material at the same R- values. There's only one answer: the general perception that R-value measures insulation performance is simply incorrect.

Insulation materials showing the same R-value will insulate equally within the scope of the standard R-value test method. The problem with this method is that is does not consider all or even most factors affecting the performance of the installed product. Some

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