July 31, 2020
By Rockford Boyer
The construction industry has a large impact on climate change through building design, material manufacturing, construction activities, building operations, and decommissioning. There is a huge opportunity for the sector to reduce its negative effects with proper design, use of assemblies with low global warming potential (GWP), efficient building operation and energy utilization, and material reuse and recycling after demolition (if carbon neutral or carbon-negative). GWP measures the ability of greenhouse gases (GHGs) to trap heat in the atmosphere.
This article focuses on the climate change potential of thermal insulation materials. According to the Pan-Canadian Framework on Clean Growth and Climate Change, “The cost of inaction is greater than the cost of action: climate change could cost Canada $21 to $43 billion per year by 2050, per 2011 estimates from the National Round Table on the Environment and the Economy.”
When it comes to conversations around global warming, insulation is interesting as it can have a negative net impact when considering factors such as raw material extraction, transportation, manufacturing, and end-of-life disposal. On the other hand, it reduces the impact of climate change from the how the buildings are conditioned.
The impact of insulation
There is confusion about the effect of insulation materials on climate change. A common misconception on the climatic impact of factory-manufactured insulating materials is “it has zero global warming potential, as the finished thermal insulation material does not contain blowing agents with high GWP.” Traditional commercial insulation types can be divided into two distinct groups. The first group comprises materials that trap air to obtain the RSI value (thermal resistance), such as fibrous insulation and open cell foams. The second group includes insulation materials that trap a higher RSI-value gas (blowing agents) in their cells to obtain a higher RSI value. The blowing agents used in closed-cell board foams and spray-applied foams have an impact on climate change. However, with the new blowing agent requirements set out by Environment Canada, the impact from blowing agents (hydrofluorocarbons [HFCs]) will be drastically reduced in the coming years. Figure 1 indicates the predicted trend in HFC emissions if the new environmental policy is enforced. The predicted reductions in HFC emissions for the next 20 years would be approximately 166 (Mt C02e).
Closed-cell foam insulations, both board stock and spray applied, use various commercially available HFC blowing agents to achieve the product’s thermal performances. The most common foam products on the market using blowing agents are expanded and extruded polystyrene (EPS and XPS), polyisocyanurate (ISO), and sprayed polyurethane foam (ccSPF). The chemical composition of the blowing agents will impact climate change through their radiative efficiency (ability to absorb energy) and by their lifetime (length of stay in the upper atmosphere). The GWP of blowing agents are compared to a baseline carbon dioxide (CO2) gas assigned at GWP 1. Figure 2 provides a list of closed-cell materials and their GWP ratings.
While it is difficult to measure the percentage of blowing agent released over the life of an insulation material, the 2018 Spray Polyurethane Foam Alliance (SPFA) environmental product declaration (EPD) estimates 10 per cent is released during manufacturing, 24 per cent when in use, and 16 per cent in a landfill. Though these numbers appear to have a significant effect on climate change, the overall life-cycle impacts from the use of some foam insulation products are still below other traditional, site-manufactured insulations.
Fibrous insulations types have high GWP impact upfront (i.e. burning coke, natural gas) whereas the majority of foam plastics using blowing agents have a continuous impact throughout its life cycle. Facings or coverings can affect the insulation’s overall GWP. However, the level of impact would depend on the type of finish (paper face, fibreglass matt, foil, etc.). Though these materials can be recycled, reused, or burnt for energy, they are landfilled at the end of their life cycles, and the resultant transportation has the least impact on GWP.
Regulatory amendments on HFCs
HFCs are being phased out as a result of the Montréal and Kyoto Protocols. Evolution of the refrigerant gas phase out is shown in Figure 3. The Montréal Protocol regulated chlorofluorocarbon (CFC) gasses as its impact on the ozone and global warming was high. Hydrochlorofluorocarbons (HCFCs) were the new, regulated refrigerant gasses due to its reduced impact on the ozone. GWP was addressed in the Montréal Protocol, but still had a large impact on global warming. The Kyoto Protocol aims to reduce GWP further.
New regulations are coming to Canada in 2021. Starting January 1, 2021, all refrigerant gases over 150 GWP will be banned in Canada. This regulation will affect many industries using HFC gases including refrigerators, automotive and building A/C units, HVAC, and building materials.
The federal government has stipulated thermal insulations with HFC blowing agents, manufactured and brought into Canada, must have a GWP of 150 or less by the end of 2020 (Figure 4). It will be important for architects and specification writers to understand these new requirements and update their master specifications and technical documents accordingly.
The next generation of blowing agents
Several foam insulation manufacturers in Canada have already made changes to their blowing agents. The ISO board stock insulation industry made these changes approximately 20 years ago, but the negative side-effect was a reduction in RSI values at cold temperatures. ISO companies are currently working on solutions to minimize the impact of cold temperature on their products. Prior to the ISO industry switching to pentane, the GWP of ISO blowing agent was similar to XPS. A ccSPF with hydrofluoroolefin (HFO) blowing agent was launched approximately five years ago. While there are several ccSPF manufactures in Canada, only a handful have a product ready to meet the 2021 regulation. SPF suppliers currently use two ultra-low GWP blowing agents—Honeywell’s nonflammable blowing agent Solstice with a GWP of 1 and Chemours non-flammable blowing agent Opteon 1100 with a GWP of 2. These are below the maximum GWP established by Environment Canada. The EPS industry does not have to change blowing agents as they are within the GWP-150 requirement. XPS manufacturers are still developing a low-GWP blowing agent solution for Canada.
The bigger picture
As an industry, it is crucial to take a holistic view when choosing materials, and not form judgments based on one key performance characteristic. A realistic approach for determining environmental impact of a wall enclosure is to calculate the total system GWP. This includes the impact from all control layers (heat/air/moisture/vapour control strategies). Some insulation products can be installed individually to meet the intent of all the control layers or several products could be systematically arranged in an assembly to meet the intent of the control layer requirement. Figure 5 provides the GWP total (cradle to grave) for all traditional insulation material types at a set thermal performance of R 1 m2K/W (5.7 hr.sf.F/BTU) and 1 m2 (11 sf). There is also a GWP total (cradle to grave) for a rubberized asphalt backed polypropylene filmed membrane, which may be required for insulating materials not performing as air/vapour/moisture barriers. Figure 5 identifies the highest to the lowest GWP insulation materials. It is apparent certain foam products with a high GWP blowing agent do not necessarily carry the highest embodied GWP.
All insulation materials, when used effectively in thermal applications, can reduce the impact buildings have on climate change by reducing heating and cooling loads. The payback of embodied carbon from thermal insulations vary based on thickness, energy use, climate, etc. However, when installed, most thermal insulation will have a greater lifetime carbon savings than the amount of embodied GWP for these insulations during manufacturing. This is not true for insulations in non-thermal applications, such as acoustics, passive fire protection, and architectural finishes (such as cladding) where the GWP used in the manufacturing process will never be recaptured through heat transfer. In these instances, it is beneficial to use materials with lower embodied GWP.
The Canadian government and Environment Canada are taking a strong stance by recognizing the harmful effects of high-GWP materials, and implementing a HFC phase-down plan. Some low-GWP alternatives are already available in the market. Although much work remains to be done to ensure the full adoption of these new technologies, industries currently using low-GWP alternatives have proven they can move quickly to protect the environment. January 1, 2021, will mark a milestone in the evolution of thermal insulation.
Rockford Boyer is the technical manager, building enclosure at Elastochem Specialty Chemicals. Boyer has a diploma in civil engineering, a degree in architecture (building science option), and a master of building science degree. Boyer has more than 15 years of experience in the enclosure design field, including five years with AMEC, Earth and Environmental, 10 years with Roxul/Rockwool Insulation, and two years with Elastochem. He can be reached at email@example.com.
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