Insulation to Keep Us Warm — Not Warm the Planet
An update on steps to reduce the global warming potential of insulation materials
I’ve been pretty vocal about a big problem with some of our most common insulation materials: that they are made using blowing agents that are highly potent greenhouse gases.
All extruded polystyrene (XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation.) and most closed-cell spray polyurethane foams (SPF) are made with HFC (hydrofluorocarbon) blowing agents that have global warming potentials (GWPs) many hundreds of times greater than that of carbon dioxide. (My apologies for contaminating this column with so many acronyms!)
Insulation: good news, bad news
Insulation materials help our homes save energy and, in so doing, they reduce the combustion of fossil fuels and the release of greenhouse gases.
But if the insulation material itself is made with a very-high-GWP blowing agent that may ultimately escape from the insulation, adding a lot of insulation may actually be a bad thing from the standpoint of mitigating climate change. All that was spelled out in my blog post two years ago, “Avoiding the Global Warming Impact of Insulation” and, in greater detail, in the EBN feature article on the same topic.
OK for ozone, bad for climate
With XPS, the blowing agent HFC-134a has a GWP of 1,430, meaning that it’s 1,430 times as potent as carbon dioxide (which is defined as having a GWP of 1). Nearly all closed-cell SPF is made with the blowing agent HFC-245fa, which has a GWP of 1,030.
Relative to global warming, these blowing agents aren’t as bad as the CFCs that were used originally, but they are as bad as the HCFCs (hydrochlorocfluorcarbons) that were adopted as second-generation blowing agents. (Both HFCs and HFOs are considered totally safe for the ozone, which is why CFCs and HCFCs have been phased out.)
Blowing agents: the next generation
Anyway, given all this, I’ve been closely following the developments by industry in coming up with alternatives that are neither ozone depleters nor significant greenhouse gases.
Two years ago, it appeared that the leading candidates were HFOs (hydrofluoroolefins), and Honeywell announced the development of such a product in 2011. And indeed, it was just announced last week that Whirlpool, the nation’s largest appliance manufacturer (with such brands as Maytag, Amana, Jenn-Air, and KitchenAid, along with Whirlpool), was switching to a new HFO blowing agent for the polyurethane insulation in all of its refrigerators.
Whirlpool will be using the new Solstice Liquid Blowing Agent made by Honeywell, one of the nation’s three producers of blowing agents (along with DuPont and Arkema). Solstice HFO has zero ozone depletion potentialAmount of damage to the ozone layer a given chemical can cause compared to trichlorofluoromethane (CFC-11), which is given a value of 1.0 on this relative scale. and a GWP of just 4.7 to 7.0—similar to that of the various hydrocarbon blowing agents used in expanded polystyrene and polyisocyanurate — and insignificant relative to global warming.
Efficiency boost an added bonus
Further, Solstice HFO will boost the R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. of the insulation material slightly. Compared with HFC-245fa, this HFO produces insulation with 2% higher R-value, and compared with hydrocarbon blowing agents it offers an 8% to 10% improvement, according to Honeywell.
While the change is exciting, it is not immediate. The HFO has just received its approvals from the government, and it will take a while to ramp up production and convert refrigerator factories to the new foam. Whirlpool expects to begin incorporating the new blowing agents into its refrigerators in late 2013.
Spray-foam manufacturers slower to adopt HFOs
But what about the closed-cell SPF insulation that is commonly used to insulate buildings?
SPF manufacturers will probably be replacing the HFC-245fa with HFO … but it’s unclear exactly when that will happen. Rick Duncan, the technical director at the Spray Polyurethane Foam Alliance (SPFA), the trade association serving the SPF industry, told me that some SPF manufacturers (“system houses”) are conducting field trials with the new HFO blowing agents, but not all of them. (At least one manufacturer, IcyneneOpen-cell, low-density spray foam insulation that can be used in wall, floor, and roof assemblies. It has an R-value of about 3.6 per inch and a vapor permeability of about 10 perms at 5 inches thick., also makes a water-blown, medium-density foam, MD-R-200, which insulates to R-5.2 per inch and is referred to as both an open-cell and closed-cell product on the Icynene website; most other water-blown SPF products are believed to have been discontinued.)
Unlike in 2003 when federal regulations mandated a switch from HCFC to HFC blowing agents due to ozone depletion concerns, there are no similar regulations requiring a switch from HFCs to HFOs.
It’s up to us
And the conversion takes time and is expensive — about one year and at least $100,000, says Duncan. With the building industry still in an economic slump, producers aren’t looking to spend a lot of additional money on product development.
Duncan believes, however, that when a new life-cycle assessment (LCALife-cycle assessment. Examination of environmental and health impacts of a product or material over its life cycle; provides a mechanism for comparing different products and materials for green building.) report on SPF comes out that SPFA is now finalizing, customers will begin asking for lower-GWP foam and manufacturers will respond by producing it. From an environmental standpoint, open-cell SPF (which doesn’t include HFC blowing agents) has just 1/20th the global warming impact of closed-cell SPF.
Less action in the XPS camp
I was not able to get as much information from the extruded polystyrene industry about when the HFC-134a might be replaced with a lower-GWP blowing agent and whether there is a gaseous form of HFO that could work for that industry. (While a liquid blowing agent is used in producing SPF, a gaseous blowing agent is required for XPS.)
Jan McKinnon, the senior communications manager at Dow Building Solutions (manufacturer of Dow Styrofoam XPS), says that the company is looking for ways to reduce its greenhouse gas emissions. “Since the launch of our new formulation in 2010 [converting from HCFC-142b to HFC-134a], we continue to look at lowering our blowing agent global warming potential, and we have an active process in place to reduce it by 15%,” she told me. She said that they are actively evaluating alternative blowing agents for XPS, “but most of these technologies are still in their infancy.”
Not a great time to invest in products
Both the SPF and XPS industries have already gone through two major transitions: from CFC to HCFC blowing agents and then from HCFC to HFC blowing agents.
With a weak building economy and depressed sales of building materials, enthusiasm for a third major conversion has been limited. But I believe that there will be growing demand to produce products with as little impact on global climate change as possible — and if this year’s heat and drought continue, that demand may well grow.
Let’s hope so.
- John Straube
- Jordan Dentz, The Levy Partnership, Inc.
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