Net positive over the building lifetime. Embodied carbon (manufacturing) is offset within 2-5 years by energy savings. Newer HFO-blown foams (zero ozone depletion potential) are dominant in 2026.
More detail
Embodied carbon for closed-cell SPF runs roughly 1.0-1.5 kg CO2e per board foot, primarily from polyol production and the blowing agent. Older formulations used HFC-245fa (high global warming potential) and HCFC-141b (ozone depleting); both have been phased out by EPA SNAP regulations. Modern formulations (Demilec Heatlok HFO Pro, BASF Spraytite HFO) use HFO-1234ze blowing agents with global warming potential under 1, eliminating the legacy concern. The carbon-payback math: a typical Cincinnati attic install (~3,000 board feet of closed-cell) carries roughly 4,500 kg CO2e of embodied carbon. The same install reduces annual heating-and-cooling carbon by roughly 1,000-2,000 kg CO2e per year. Net carbon benefit shows positive within 2.5-4.5 years and continues for the 50+ year material lifespan. Cellulose has lower embodied carbon (mostly recycled paper) but does not match the air-sealing performance, so the lifecycle comparison varies with assumptions. Cincinnati lifecycle-carbon analysis context: a typical Cincinnati attic foam install (3,000 board feet of closed-cell with HFO blowing agent) carries roughly 4,500 kg CO2e of embodied carbon. The same install reduces annual heating-and-cooling carbon by 1,000-2,000 kg CO2e, paying back the embodied carbon in 2.5-4.5 years. Over the 50+ year material lifespan, lifecycle CO2e is solidly net-negative. Cellulose has lower embodied carbon but the air-seal-performance gap means full lifecycle comparisons depend on assumptions.