Which types of refrigerants have the lowest global warming potentials (GWPs)?

• A. HFOs, HCs
• B. Ammonia and CO2
• C. HCFCs and R-22
• D. HFCs

Answer: (A)

Global warming potential compares how much heat a refrigerant traps in the atmosphere over a set time, relative to CO2. So, refrigerants with the smallest GWP have the least climate impact. Among the common families, hydrofluoroolefins (HFOs) and hydrocarbons (HCs) typically have the lowest GWPs. HFOs break down relatively quickly in the atmosphere and have radiative effects that keep their GWP values in the single digits to low tens. Hydrocarbons like propane or isobutane lack chlorine and fluorine, further reducing their long-term warming impact and giving them very low GWPs as well. In contrast, HCFCs and R-22 contain chlorine and have much higher GWPs; HFCs often carry high GWPs too. Ammonia and CO2 do have very low GWPs (ammonia near zero, CO2 around 1), but within the listed options the combination of HFOs and hydrocarbons represents the refrigerant families with the overall lowest GWPs, making this choice the best fit.