I recommend that you read the original blog post before reading my post which is actually a comment on the original debate. Here’s the link: http://www.greenbuildingadvisor.com/blogs/dept/musings/it-s-ok-skimp-insulation-icynene-says

For what we know about the actual formula to calculate R-values, it is based on conduction prevention. It has nothing to do with blocking air-leaks. This is a VERY interesting argument. One thing I want to point out is that the requirement of r-values in building codes has INCREASED 30% or more in most areas of the US in the last 5-10 years.

Since many structures insulated with mineral fiber types of insulation the air-leakage can easily result in a 40% heat loss/gain. The code officials decided that instead of monitoring the air tightness and retesting the actual air-sealing benefits of spray foam and other types of insulation that make a building air-tight, they would take one simple factor – R-VALUE – and go home with their Owens-Corning sponsor money.

What should take place is a total re-evaluation of the requirements to make the home energy efficient upon the sale of the home. Each region has and should have it’s own set of regulations. Blower door tests should be performed to determine a minimum air-seal requirement (which exists but is overlooked). Then these test shells should be evaluated for their heat loss/gain using different products and r-values.

Once the tests are performed and evaluated new codes should be written and put into action. Of course this means that every home being built/sold will have to undergo a blower door test to check for air-tightness which brings the cost of a home inspection up significantly (one reason why it has been avoided.) Also, if the home fails the tightness factor there are few options other than spray foam and/or a complete renovation to solve the issue.

I disagree with the silly practices of Icynene but understand that they are trying to make a HUGE point when it comes to raising r-value codes to compensate for heat loss/gain. Code officials should understand the difference between the air-tightness of a home and the conductive values eliminated by insulation. Test the theories and re-write the codes.