Ecologic Guides · Environment
HFO vs HFC spray foam: what changed and why it matters
Direct answer
A blowing agent is the gas that expands liquid foam and stays sealed in its cells. Until recently, most closed-cell spray foam was blown with HFC-245fa, a greenhouse gas with a global warming potential around 1,030 times that of carbon dioxide. Canada prohibited manufacturing HFC-blown foam as of January 1, 2021 under the federal HFC phase-down. The industry moved to HFOs (hydrofluoroolefins): the closed-cell foam we install carries a GWP of 1 per its 2024 technical data sheet, a 99.9 percent blowing-agent reduction the manufacturer documents against HFC alternatives. Our open-cell foam is water-blown. The switch also touches performance, because the blowing agent is part of what gives closed-cell foam its R-value. If a contractor cannot tell you which blowing agent their foam uses, ask to see the TDS.
Sources: ECCC HFC regulations · manufacturer TDS 2024 · ACS C&EN
01 The chemistry, briefly
What is a blowing agent and why does foam need one?
Spray foam arrives on site as two liquids. When they mix at the gun, they react and expand to many times their liquid volume, and something has to do the expanding. That something is the blowing agent: a gas, or a liquid that flashes to gas in the heat of the reaction, inflating millions of tiny cells as the plastic sets around them.
In closed-cell foam the cells seal shut and the blowing agent stays inside, where it does double duty. It conducts heat more poorly than air, which is a large part of why closed-cell foam insulates at roughly R-5 to R-6 per inch while air-filled insulations sit near R-3.5. Open-cell foam works differently: its cells pop open as they form, the gas escapes during curing, and the cured foam holds plain air.
So the choice of blowing agent decides two things at once: how the foam performs as insulation, and what happens to the atmosphere as the gas slowly works its way out over the decades. For most of spray foam's history, the second part was the industry's worst number.
02 The problem
The HFC era: insulation with a heavy exhaust
Through the 2000s and 2010s, the standard blowing agent for closed-cell spray foam was HFC-245fa, a hydrofluorocarbon. It made excellent foam. It was also a potent greenhouse gas: chemical-industry references put its global warming potential at roughly 1,030 times that of carbon dioxide, kilogram for kilogram, over 100 years.
Blowing agent is a small fraction of the foam by weight, but a multiplier above 1,000 makes small fractions count. Gas lost during spraying, gas diffusing out over the foam's service life, and gas released if the foam is ever demolished all carried that multiplier. Critics who called older closed-cell foam a climate problem had a real point, and the honest thing to say in 2026 is that they were right about the foam of that era.
03 The regulation
What did Canada do about HFC foam?
Canada ratified the Kigali Amendment to the Montreal Protocol in 2017 and wrote the HFC phase-down into federal law through Environment and Climate Change Canada's amendments to the halocarbon regulations. Alongside a stepped reduction in bulk HFC supply, the amendments prohibited specific products outright. For foam, the line fell on January 1, 2021: from that date, manufacturing HFC-blown foam in Canada was prohibited under the phase-down, with high-GWP HFC foam products shut out of the market.
The practical effect was industry-wide reformulation. Every major closed-cell foam sold in Canada today is blown with an HFO or another low-GWP agent, and has been for several years. Pre-2021 formulations are gone from the supply chain, though marketing copy written for them still circulates, which is one reason to date every document a contractor hands you.
For the foam we install, the paper trail is current on both ends: the 2024 HFO-formulation technical data sheet carries CCMC 14133-L, and the CCMC listing itself was modified August 2024 and stands Active. The current HFO formulation is the product on CCMC listing 14133-L as modified August 2024.
04 The replacement
What is an HFO, and is GWP 1 for real?
HFO stands for hydrofluoroolefin. The molecule carries a carbon-carbon double bond, and that bond is its whole climate story: it makes the compound reactive enough to break down in the lower atmosphere within days to weeks. HFCs, with no such weak point, persist for years and accumulate. A gas that disappears in days never builds up enough to warm anything much, which is how HFOs land at global warming potentials around 1, on par with CO2 itself.
For the closed-cell foam we install, the manufacturer's 2024 technical data sheet states an ultra-low GWP rating of 1 and documents the switch as 99.9 percent less harmful than HFC alternatives. We repeat those figures as manufacturer statements, sourced to the TDS, the same way we source every number on this site. Chemical-trade coverage of the HFO transition tells the same story across the industry: blowing agents went from a climate impact hundreds to thousands of times CO2 down to parity with CO2.
| Blowing agent | GWP | Status in Canada | Where you find it |
|---|---|---|---|
| HFC-245fa | ≈1,030 | Foam manufacture prohibited Jan 1, 2021 | Pre-2021 closed-cell foam |
| HFO | 1 | Current standard | Our closed-cell (Grizzly Gold, TDS 2024) |
| Water-blown (CO2) | Ultra-low, zero ODS | Current | Our open-cell (Grizzly 005) |
05 The side-effect
Blowing agents decide long-term R-value too
The gas in the cells is a working part of the insulation, so how long it stays there sets how well the foam holds its R-value. This is the physics behind LTTR, the five-year design value Canadian standards require: fresh foam tests high, then settles as blowing agent and air slowly trade places through the cell walls.
HFO retention is part of why current foam publishes the thickness ladder it does: R-5.3 at 1 inch rising to R-24.1 at 4 inches, per-inch performance climbing with thickness because thicker foam holds its gas better. The industry consensus is that HFOs diffuse out more slowly than the agents they replaced, which supports long-term retention. Either way, the number that matters on a quote is the tested LTTR at your thickness under the current method, CAN/ULC-S770-15. How those values are measured, why per-inch figures mislead, and which numbers Efficiency Manitoba accepts is the subject of its own guide: Spray foam R-values and LTTR.
06 Full accounting
Is spray foam green now? The honest ledger
A company named Ecologic should be the last one to hand-wave this. Both columns, in plain terms.
What improved, and what counts in favour
The blowing agent problem was solved. GWP fell from about 1,030 to 1, a 99.9 percent reduction in the largest single emission source foam had.
Decades of avoided heating energy. In a 5,670 heating-degree-day climate, insulation and air-sealing cut fuel or electricity use every winter for the life of the building. Over decades, that avoided energy is the dominant term in the ledger for most retrofits, which is the qualitative logic of carbon payback. We will not invent a payback year for your house; the direction of the math is clear even where the exact figure depends on the fuel, the assembly and the energy grid.
Open-cell is water-blown. Zero ozone-depleting substances, ultra-low GWP, Greenguard Gold certified for low chemical emissions.
What stays on the other side of the ledger
Foam is petroleum-derived. Polyurethane comes from fossil feedstocks, and its manufacture carries embodied carbon like every insulation, more than some.
It is effectively permanent. Adhesion is the point of the product, and it cuts both ways: foam does not come off framing cleanly, is impractical to recycle, and complicates future renovation of whatever it covers.
Removal is hard. Where foam is misapplied, fixing it is slow, manual work. That is an argument for specifying it correctly the first time, with a contractor who documents what went on the wall. Our guide to hiring a spray foam contractor covers what that documentation looks like.
07 Due diligence
What to ask any contractor about their foam
- Which blowing agent does your closed-cell foam use? The answer in 2026 should name an HFO without hesitation. Pre-2021 stock is gone from the supply chain; old marketing language is not.
- What year is the TDS you are quoting from? A technical data sheet dated before 2021 describes a foam nobody can legally manufacture in Canada today. Ask for the current sheet and check that the R-values on the quote match it.
- Is the product CCMC-listed, and is the listing active? The listing number should appear on the quote. Ours is 14133-L, and the registry entry is public.
- If the pitch leans green, what backs it? "Eco-friendly" costs nothing to print. A GWP figure with a document behind it, a water-blown open-cell TDS, or a Greenguard certificate is verifiable; adjectives are not. The same discipline applies to health claims, which we cover in Is spray foam safe?
08 Questions
Blowing agents, answered
Is spray foam bad for the environment?
It is mixed, and anyone who tells you otherwise is selling something. The blowing-agent problem that made older closed-cell foam a heavy emitter was solved: Canada prohibited HFC-blown foam in 2021, and current HFO foam carries a GWP of 1. The foam itself is still petroleum-derived, effectively permanent, and hard to remove or recycle. Against that stands the energy it saves every heating season for the life of the building, which in a 5,670 heating-degree-day climate is a large, compounding number. For most Manitoba retrofits the operational savings dominate the footprint over time.
Source: ECCC HFC regulations · manufacturer TDS 2024
What is an HFO?
HFO stands for hydrofluoroolefin, a family of blowing agents with a carbon-carbon double bond that makes the molecule break down in the atmosphere within days to weeks instead of persisting for years the way HFCs do. That short life is why HFO global warming potentials sit around 1, on par with carbon dioxide, versus roughly 1,030 for the HFC-245fa they replaced. The closed-cell foam we install is HFO-blown per its 2024 technical data sheet.
Source: ACS C&EN · manufacturer TDS 2024
Is new spray foam better than old spray foam environmentally?
On the blowing agent, dramatically: the manufacturer documents a 99.9 percent reduction in blowing-agent climate impact for the current HFO formulation versus HFC alternatives, and the GWP went from about 1,030 to 1. The polyurethane itself is essentially the same material it was, with the same embodied carbon and the same permanence. So a 2026 install avoids the single largest emission source older foam had, while the rest of the accounting is unchanged.
Source: manufacturer TDS 2024
What does GWP 1 mean?
GWP, global warming potential, compares a gas to carbon dioxide kilogram for kilogram over 100 years. CO2 is the yardstick at GWP 1. A GWP of 1 for the HFO blowing agent means a kilogram escaping to the atmosphere warms about as much as a kilogram of CO2. A kilogram of HFC-245fa, at roughly 1,030, warms about as much as a tonne of CO2. That ratio is the whole argument for the switch.
Source: ACS C&EN / industry references
Is open-cell foam greener than closed-cell?
Open-cell foam is water-blown: the reaction generates CO2 to expand the foam, so there is no fluorocarbon in the cells at all, and the product we install carries zero ozone-depleting substances and a Greenguard Gold certification for low chemical emissions. Since current closed-cell foam is also at GWP 1, the blowing-agent gap between the two has mostly closed. Pick between them on the job's physics, vapour control, moisture and R per inch, rather than on green marketing.
Source: Grizzly 005 TDS 2021 · Grizzly Gold TDS 2024
Sources
Where these numbers come from
- Environment and Climate Change Canada: regulatory amendments on hydrofluorocarbons: the HFC phase-down and the product prohibitions, including foams, effective January 1, 2021.
- CUSE Grizzly Gold technical data sheet, 2024 edition: HFO blowing agent, GWP rating of 1, 99.9 percent reduction versus HFC alternatives. Grizzly 005 TDS, 2021: water-blown, zero ODS, Greenguard Gold.
- Chemical & Engineering News (ACS): HFO foam-blowing agents: chemical-trade coverage of the transition from high-GWP HFCs to HFOs with warming impact on par with CO2.
- CCMC evaluation 14133-L: the National Research Council listing carried by the current HFO formulation, modified August 2024, status Active.
Ask us the blowing-agent question. We like answering it.
TDS, CCMC listing and R-value math attached to every written quote.