First, a bit of background on the CMHC Materials Guide

Canada has a housing problem, and everyone in the industry knows it. To help address it, CMHC (Canada Mortgage and Housing Corporation) released its 2025 Materials Guide as part of the Housing Design Catalogue. The idea was to give builders, designers, and project teams a common reference for comparing building materials based on cost, lifespan, and environmental impact.

It’s a useful tool. And as affordable housing becomes a bigger national priority, it’s going to carry more and more weight in how projects get specified and approved.

This is exactly why getting the numbers right matters so much.

So what’s the problem?

A May 2026 analysis in Canadian Contractor magazine by Mickel Maalouf, a LEED Green Associate and Sustainable Building Science Manager at Huntsman Building Solutions, caught something worth paying attention to. The Guide lists global warming potential (GWP) values for several insulation materials that appear to be significantly lower than what those same products declare in their own Environmental Product Declarations, or EPDs.

EPDs are the gold standard for this kind of data. They’re standardized, produced by the manufacturers themselves, and independently verified by a third party. If the Guide’s numbers don’t line up with EPDs, that’s a meaningful discrepancy.

Here’s what Maalouf found. GWP is measured in kg of CO₂ per square metre at RSI-1, which is just a way of comparing insulation products on equal footing regardless of thickness.

Read that table carefully. Mineral wool and fibreglass look much better in the Guide than their own EPDs suggest they should. Spray foam, meanwhile, is listed at a value that’s actually higher than current EPD data. The result is a comparison that tilts against spray foam in a way that the real-world numbers simply don’t support.

The chemistry of spray foam has changed dramatically. The Guide doesn’t reflect that.

This part is very important. The spray foam sold in Canada today is a fundamentally different product than it was even a few years ago.

Canada phased out HFC (hydrofluorocarbon) blowing agents under the Kigali Amendment to the Montreal Protocol. Every compliant closed-cell spray foam product in the country now uses HFO (hydrofluoro-olefin) technology instead.

That’s not a small tweak. The old HFC blowing agents had a GWP of 700 to 1,000. HFO brings that below 3. That’s a reduction of more than 99%.

The blowing agent used to be the biggest source of embodied carbon in spray foam. Now it’s barely a factor. That changes the whole picture.

Maalouf also notes that the industry is finalizing an updated EPD that will more accurately reflect today’s HFO formulations. The numbers are expected to come down further still.

Embodied carbon is only half the equation

Here’s something that often gets missed in these conversations. The carbon a material produces during manufacturing is just one part of its environmental footprint. The other part is how much energy the building uses over its lifetime because of how well, or how poorly, the insulation performs.

Spray foam creates a continuous, airtight seal that other insulation products can’t replicate. In our Canadian climate, that matters a lot! Heating loads are heavy and they last for months. A building envelope that leaks air is a building that’s constantly working harder than it needs to.

Industry data suggests spray foam’s air-sealing performance can cut heating and cooling energy use by 20 percent or more. And with HFO chemistry, the carbon payback period, meaning the point where those operational savings outweigh the product’s upfront embodied emissions, can be as short as three to seven years.

For a home that’s going to stand for 50 years, that’s a pretty compelling case.

What should homeowners and builders actually do with this information?

A few practical steps if you’re making insulation decisions right now:

• Don’t rely on the Guide alone. Ask for current EPDs for any product you’re comparing. That’s where the verified data lives.
• Look at the whole lifecycle. A product with a lower embodied carbon number but weaker thermal performance can easily end up being the worse environmental choice over a 30 or 50-year building life.
• Ask what blowing agent is being used. Every compliant spray foam in Canada is HFO-based today. If someone is showing you comparisons that don’t reflect that, the comparison is out of date.

At Koala Insulation we only use current, HFO-based spray foam products with our spray foam services. We’re always happy to walk through the data with you. Whether you’re a homeowner trying to make a smart upgrade decision or a builder working through a specification, we can help you understand what you’re actually comparing.

Source: This post draws on analysis originally published by Mickel Maalouf in Canadian Contractor magazine (May 2026). EPD data referenced in the comparison table is sourced from product-specific and industry-wide Environmental Product Declarations as cited in that article.