How does blowing agent choice in spray foams affect environmental impact and R-value?

• A. Blowing agents affect color and odor of foam.
• B. Blowing agents determine Global Warming Potential (GWP); modern foams use lower-GWP agents (HFOs, hydrocarbons); these choices can affect both environmental impact and performance.
• C. Blowing agents do not influence environmental impact.
• D. Blowing agents only influence curing time.

Answer: (B)

Blowing agents are the gas trapped inside the foam’s cells, and that gas is the main path heat uses to move through the foam. Because heat transfer depends on the properties of that trapped gas, the blowing agent directly influences the foam’s insulating value, i.e., its R-value per inch. Different agents have different thermal conductivities, so switching to a gas with lower heat transfer can improve the foam’s insulating performance, while still maintaining or even enhancing how the foam fills and cures.

At the same time, the blowing agent determines the environmental impact through its Global Warming Potential (GWP). Older foams used agents with high GWP, which contributed more to climate effects if released. Modern formulations replace those with low-GWP options like certain HFOs or hydrocarbons, which reduces environmental impact. These modern choices are designed to preserve or improve insulating performance while cutting climate impact.

Color, odor, and curing time aren’t driven primarily by the blowing agent in the same way. The main effects you’ll notice from changing blowing agents are the environmental impact (GWP) and the insulating performance (R-value).