What is Global Warming Potential (GWP)?
GWP measures how much heat a greenhouse gas traps in the atmosphere over 100 years, relative to carbon dioxide. CO2 is the reference and has a GWP of 1. A refrigerant with GWP 2,000 is two thousand times more potent as a greenhouse gas than the same mass of CO2.
What is Ozone Depletion Potential (ODP)?
ODP measures a substance's ability to destroy stratospheric ozone, relative to R-11 (ODP = 1.0). CFCs like R-12 have ODP near 1.0 and are banned under the Montreal Protocol. Modern HFC, HFO, and natural refrigerants have an ODP of zero and do not harm the ozone layer.
What do ASHRAE safety classifications (A1, A2L, etc.) mean?
The letter indicates toxicity: A = lower, B = higher. The number indicates flammability: 1 = non-flammable, 2L = mildly flammable (low burning velocity), 2 = flammable, 3 = highly flammable. A1 (e.g. R-134a, R-410A) is the safest; A3 (e.g. propane R-290) is highly flammable but has excellent thermodynamic performance.
What is the difference between AR4 and AR5 GWP values?
AR4 (2007) and AR5 (2013) are two IPCC assessment reports. They use slightly different radiative-efficiency and lifetime calculations, so the same refrigerant can have a different GWP under each. For example, R-134a is 1,430 (AR4) vs 1,300 (AR5). Regulatory schemes typically specify which report's values to use; this database uses AR5 unless noted.
Which refrigerants are being phased out?
CFCs (R-11, R-12) are already banned globally. HCFCs (R-22, R-123) are being phased out under the Montreal Protocol. High-GWP HFCs (e.g. R-404A at GWP ~3,900, R-410A at ~2,000) are being phased down under the Kigali Amendment, the EU F-Gas Regulation, and the US AIM Act. Replacements include HFOs (R-1234yf, R-1234ze), low-GWP blends (R-454B, R-454C), and naturals (CO2, ammonia, propane).
How do I calculate CO2-equivalent (CO2e) for a refrigerant leak?
Multiply the mass of refrigerant (in kg) by its GWP, then divide by 1,000 to get tonnes CO2e. Example: 5 kg of R-410A (GWP 2,088) leaking fully = 5 x 2,088 / 1,000 = 10.44 tonnes CO2e. Use the calculator at the top of this page for any refrigerant and charge size.
What is a "low-GWP" refrigerant?
A refrigerant is generally considered low-GWP when its value is below 150. This includes HFOs (R-1234yf at <1), hydrocarbons (R-290 propane at 3.3), CO2 (1), and ammonia (0). Many new blends (R-454A, R-454C) are designed to fall under 150 to qualify for exemptions from phase-down quotas.
Are hydrocarbon refrigerants like R-290 (propane) safe?
Hydrocarbons are class A3 (highly flammable), but charge-size limits and proper engineering make them safe for domestic and light-commercial use. R-290 (propane) and R-600a (isobutane) are now standard in household refrigerators and small freezers worldwide because of their very low GWP (around 3) and excellent efficiency.
Where do these GWP values come from?
GWP values are taken from the IPCC Fifth Assessment Report (AR5, 2013) and cross-referenced with ASHRAE Standard 34 and the U.S. EPA Significant New Alternatives Policy (SNAP) program. Blend GWP values are mass-weighted averages of their components. Always verify the exact value required by your local regulation before compliance reporting.