Spray Foam’s Pollution Reduction Outweighs Initial GHG Impact
A new report modeling SPF’s impact on the CO2 footprint of a home over its lifespan finds huge differences in impact, based on the type of blowing agent.
Every time I conduct a webinar about building science or making homes more resilient, I get critical emails from attendees about my inclusion of spray foam as an insulating mainstay. But I have continued to include it, because in terms of insulating value per inch and air sealing of conventional stick-framed homes, I haven’t encountered anything better in terms of performance.
The critics are not wrong in their concern about the high embodied footprint of SPF and its reliance on volatile chemicals, including catalysts, flame retardants and Isocyanates. I’d love to see more natural materials used in the mix by all SPF makers. But despite these caveats, I’ve frequently argued that the high initial impact is worth the environmental trade off over a home’s lifespan.
Now I can back up those assertions. A new life cycle analysis comparing spray foam with other conventional types of non air sealing insulation has just been released. The report evaluates SPF’s lifespan pollution footprint using carefully modeled virtual homes: “The model home for each climate zone was standardized to a typical single-family detached home above grade, two-stories, four bedrooms over an unconditioned, vented crawl space with an insulated floor.”
The good news: When the right blowing agents are used in SPF production, the estimated saving in energy use rapidly compensates for the production phase. That’s largely because of foam’s air sealing attributes.
An SPF insulated home can achieve the low air changes per hour (ACH) that puts it immediately in the top ranks of home energy efficiency, which means drastic reduction in fossil fuel use for heating or cooling. In fact, the study estimates a potential payback period (in terms of GHG emissions reduction) of about three years, if closed cell spray foam made with hydrofluoroolefin (HFO) is used.
Not every SPF scenario pays its way, however. Spray foam made with hydrofluorocarbons (HFC) has a very poor pathway toward sustainability. The pollution payback estimate for a home insulated with closed cell SPF made with HFC is 80 years. This ought to put to the sword any use of SPF manufactured with HFC. These compounds are supposed to phase out in many products soon, but make sure you look at the specs before you hire a spray foam supplier.
Here’s Why: Take a look at this table from the study: The chart compares the Global Warming Potential for the total volume and type of spray foam or fiberglass used in three model homes, one in each geographic city/location.
The bottom line. SPF has a legitimate, pollution-reducing life-cycle story to tell, but only if the product is created using more benign chemicals than earlier HFC versions of the insulation.