Benefits and Challenges in Using Low GWP A3 Refrigerants in Residential Air Conditioning Equipment

Propane gas is a very low-global warming potential refrigerant that provides good cooling equipment performance. The flammability of propane, however, makes the management of equipment design, handling, and maintenance critical factors to ensure that any cooling equipment with propane refrigerant is safe to use across a product’s lifetime. Flammable refrigerants are mostly used in units with small cooling capacity, particularly in factory-sealed units since these have the lowest risk of refrigerant leakage. 

This project focused on the potential climate benefits and costs of transitioning to propane refrigerant in three types of small-room air conditioning units (window air conditioning, packaged terminal air conditioning/heat pumps, and mini-split heat pumps). The team modeled optimized designs, tested results of these types of air conditioning units with propane, and estimated net impacts to greenhouse gas emissions and consumer costs for California over the next three decades. 

Modeled results show that small air conditioners have the highest market favorability and the ability to meet refrigerant quantity limits (per unit) set by United States Environmental Protection Agency in 2015. Between 15 and 66 million metric tons of greenhouse gas savings were estimated if these three types of air conditioning units shifted to propane refrigerant between 2022 and 2051, compared to using baseline refrigerant R-32 and R-410A, respectively. An estimated savings of $44.50 per ton of carbon dioxide equivalent is possible due to lower operating costs of R-290 due to higher energy efficiency than baseline refrigerants.