Foam Insulation-The Ultimate Barrier to High Energy Bills?

Icynene®, one of my ten favorite green building products, is an open-cell spray foam insulation. It basically provides a barrier to prevent drafts, condensation, and outdoor allergens from penetrating the building envelope. From personal experience, this is an amazing product. [Note: This article was written on September 14, 2007, and was believed to be accurate at the time of writing.]

Icynene was installed inside the cavities of our exterior walls including the basement walls. I have a geothermal system and swear my energy bills are so low because of the combination of the two. I run my house at 76 to 78 during the summer (but at 74 at night on the second floor) and am quite comfortable. In the winter I run the house at 68.  My air conditioning never runs in the basement and it never feels humid.

It is expensive compared to the other insulations. A couple of years ago, I paid $1.40 for a board foot (northeast prices).  A board foot is a 1 foot by 1 foot by 1 inch thick square. For my area, it is recommended that there is 6 inches of depth in each cavity wall. (Each board foot is equal to R 3.6) However, in my opinion this insulation is a superior product to fiberglass or other insulations because of the air barrier. Why open-cell versus closed-cell? Closed-cell is denser and therefore more expensive. However, it has a higher R value than an open-celled insulation. We chose open-cell insulation because we were told the closed-cell insulation offgassed chemicals. This may or may not be true, but at the time we installed our insulation, I was frightened by the prospect. In addition, if there was a water leak, I would find it easier with an open-cell insulation because water can move through it unlike closed-cell. Some people prefer closed-cell because of its higher R value, and it provides a better air barrier.

Icynene has different applications depending on whether its use is for new construction, existing construction, or touch-ups.  Icynene Insulation System® has two different formulas: sprayed and pour. “Icynene’s pour fill variation is an insulation and air barrier that injects the... [product] into an older building to maximize energy efficiency while still preserving its original architectural details,” according to the makers of Icynene. If you have a small project or need a touch up, then Gold Seal 400 ® is the product you would use.

In addition, on their Web site, there is a chart comparing different insulations to Icynene in certain categories such as "damaged by water", "R value", and "harmful emissions produced" after installation is complete. (Remember, this chart is produced by Icynene, not a third party, so use it as a guide.)

Does it have a downside?  Ic...