The honest answer is mixed - and improving. Spray foam's environmental case rests on the energy it saves over a building's life, and modern closed-cell foams have moved to low-GWP blowing agents. Against that, it's a petrochemical plastic, so it's not 'green' in a natural-material sense. Here's the balanced view.
The case for
- Lifetime energy savings: the biggest environmental impact of a building is the energy it uses; a foam air-seal cuts that for decades.
- Better blowing agents: newer closed-cell uses low-GWP HFO agents instead of the older high-GWP HFCs.
The case against
- It's a plastic product with embodied carbon from manufacture.
- It's not easily recyclable at end of life.
The net
For a building that would otherwise waste energy every winter, the decades of savings typically outweigh the embodied impact - especially with low-GWP foam. It's a defensible choice on energy grounds, stated honestly rather than greenwashed. See closed-cell. Get a quote.