Documented Payback: Spray Foam Insulation

Documented Payback: Spray Foam Insulation

One of the most popular questions we get from prospective customers is “when can we expect a payback from spray foam insulation?” The answer? Well that can vary greatly depending on multiple things. So I thought I would try to answer that question with an independent source study.


In 2009 as part of the US DOE Building American Program, the Florida Solar Energy Center, CPS Energy, and Woodside Homes built three homes. They all had the same floor plan and size. These three homes had different types of insulation (blown fiberglass and spray foam) and used different HVAC systems in the upgraded homes. The idea was to see if the upgraded homes would really save energy. What they found was what we expected and what we see on almost every job we do. The spray foam insulated homes simply outperformed the “build to code” homes.

In fact, the improved homes (those with spray foam insulation and upgraded HVAC systems) saved anywhere form 55-77% in energy on average. This was tested in July of 2009 and continued until it ended in April of 2011. I would say that’s impressive!

There are a couple of things I would like to point out here. First, on the improved homes they used open cell spray foam in a conditioned attic assembly. In southern climates, this is key to keeping energy costs low. However, conditioned attics work in most climates.

Second, HERs ratings on these homes ranged from 86 on the controlled home to 54 and 37 on the improved homes. I think this gives the HERs rating system validation. It is a really good predictor of how to analyze the home before and after it is built and the amount of energy being used.

The third thing that needs pointing out is the amount of air changes per hour, or ACH50. On the control home built to standard code, it had 5.84 ACH50 versus the improved home with open cell spray foam insulation only had 1.95 ACH50. Basically, the spray foam home was over 66% tighter home. Meaning it leaks a third of the air that a blown fiberglass insulated home does. Now, from previous blogs we have learned that air leakage is important.

Another thing to keep in mind is that the control home had R-30 blown fiberglass installed in the attic. The improved home had open cell spray foam installed at R-28. Just as we have said before, R values do not indicate actual performance (see this blog for further explanation).

So what we have learned is investing in upgraded insulation (even with a lower R value) and building a tighter home equals a quick payback. Keep in mind these are not our findings, but rather that of several independent organization’s findings. Invest in your building with spray foam insulation. Give us a call.