Wednesday, October 6, 2021

Does foam insulation cause greenhouse gas emissions?

Is the insulation materials that we use to help save energy and combat climate change, also causing carbon emissions?
Materials for insulation used to save energy, also help in preventing climate change and cause greenhouse gas emissions.

Indeed they do and in more than one way. 
It is the first that it requires energy to make and transport these materials, which we call as "embodied energy"--and the use of fossil fuels to fulfill these energy requirements creates carbon dioxide (our major greenhouse gas). In a way, every insulation material has embodied Global Warming Potential (GWP). Two of the most commonly used insulation materials contain Hydrofluorocarbon (HFC) blowing agent which are extremely powerful greenhouse gases. The extruded polystyrene (XPS) is most well-known by the brand names Dow Styrofoam ("Bluebeard")"blueboard") Owens Corning Foamular ("pinkboard")"pinkboard") up to R-5 per inch. It is manufactured using HFC-134a that has a greenhouse gas GWP of 1,430 which means that it's 1430 times as powerful a greenhouse gas as carbon dioxide. (I must mention here that I'm still not 100% certain that XPS is made using HFC-134a, as manufacturers are hesitant to disclose the specific blowing agents they employ as they claim the information is confidential and that the safety data sheets haven't been updated to reflect the latest blowing agents that are mandatory on January 1st, 2010. However, a few hints in the technical documents have led me think it is this blowing agent employed.) Another insulation material produced using a blowing agent with high-GWP can be described as closed-cell spray polyurethane foam (SPF). The insulation material is sprayed into the building cavity or onto foundation wall, or onto roofs. It is then will insulate to around 6 R per square inch. A majority but not all closed-cell SPF is produced using HFC-245fa which has the 1.030 GWP. Certain closed-cell SPF is water-blown, eliminating this risk, even though the majority of them are HFC-blown. The open-cell (low-density) SPF like Icynene is completely water-blown and therefore has a low GWP. Lifetime GwP A blowing agent having A significant GWP is only a problem in the event that the chemical releases in time. Unfortunately there isn't much information about the speed at which this happens. Certain researchers, like L.D. Danny Harvey, Ph.D. of at the University of Toronto (who first expressed concern about their high-GWP foam insulation in a technical paper just a few years ago) is assuming that the portion of the blowing agents disintegrates in time, however, after speaking with experts from the industry, our research of Environmental Building News The company makes an alternative, more conservative approach that only about 50% leaks out over the duration of the insulation, which could be between 50 and 500 years.

Click on the image to open the entire table.

When we mix the two sources (embodied the GWP, and the GWP that is related to the blowing agent that is used) in the case of an insulation product, we get what is known as the "lifetime the GWP" from these substances. For insulation materials that are made using HFC blowing agents, the bulk of the total GWP is out of the blowing agent. The table below outlines the assumptions we made within our EBN article. Payback of the lifetime GWP

If we can then determine how much energy a particular amount of insulation can save over the course of its lifespan (which is contingent on the location of the home situated and how efficient its heating and cooling system is) we can figure out how much "payback" from the life-time GWP of the insulation. This is the time required for the energy savings of the insulation to cover carbon dioxide emissions that result from the usage of this insulation. With the assistance by John Straube and Daniel Bergey from the Building Science Corporation in Westford, Massachusetts, we determined the paybacks when the use of different quantities of the insulation materials. This analysis is published in the June issue of Environmental Building News for those wanting to examine the results in greater depth. We examined the possibility of adding R-5 intervals of insulation in a two-by-six wall system that is insulated using dense-pack cellulose (whole-wall R-value 14 for the wall to be used as the starting point). The energy model assumes that the structure is located situated in a relatively cold Boston climate. This is illustrated in two graphs. The positive side is that, aside from XPS and HFC-blown SPF the payback time for the lifetime GWP for insulation materials is quite low. If you add 4 inches of polyisocyanurate (R-25) to the wall of 2x6, for instance, (R-39 total) the lifetime GWP payback for the additional polyiso insulation would take 2.7 years. If you get to an R-60 final value for the wall (adding 7.5 inches of polyiso) then the payback will be just a little over four years.

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If it's XPS that you're adding to your two-by-six wall, the payback time for the insulation added is more extensive. One inch of XPS will pay back 36 years in. If you add two inches, the payback increases to 46 years and when you add four inches, it's 65 years. If you go to an R-value of R-60 (adding approximately nine inches worth of XPS) will yield an average payback of more than 110 years. For SPF the paybacks will be the same, although slightly lower. 

Bottom Line: Avoid XPS and SPF. What does all this mean? These variations are significant enough that even if the assumptions are incorrect by a significant amount and we are able to draw generalizations about the best choices. If we're building extremely insulated structures and are doing it in part in order to limit global warming, we must utilize insulation materials other than XPS or SPF at a minimum until the insulation materials are made using blowing agents with lower GWP. (Low-GWP blowing agents like hydro fluoro olefins (HFOs) are most likely to come from Honeywell as well as DuPont over the coming years, but it's not known how fast XPS, as well as SPF manufacturers, will switch to these compounds or others.) There are many good alternatives. Today, polyisocyanurate (a commonly used foil-faced rigid insulation material that is sold under various trade names like Rmax, ACFoam and Thermax, ACFoam Rmax, and ACFoam Rmax) is produced using pentane, a blowing agent its GWP is extremely low (the pentane GPW is around 7). Expanded Polystyrene (EPS also known as beadboard) is also produced by blowing pentane agent. Open-cell SPF, like Icynene is made using water as a blowing agent. Mineral wool, fiberglass and cellulose don't make use of blowing agents in any way. It is important to note it is important to note that XPS or closed-cell SPF provides an array of exceptional performance properties (controlling the flow of water and airflow in the envelope of our buildings) Therefore, when we choose to use for a different type of material, we must tackle these building science issues with care. The main point will be that when it comes time to are insulating our homes to ensure that they consume less energy, and therefore contribute to reducing the effects of the effects of climate change, we must be aware of the type of insulation we select. Insulate your home to a high degree using XPS and closed cell SPF can counteract the effects of that good-willed effort. I invite you to post your thoughts in this post. What will this information mean for your selection in insulation material?

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