The May 2025 UNEP/ASHRAE Fact Sheet provides updated refrigerant designations and safety classifications according to ANSI/ASHRAE Standards 34 and 15, including flammability, toxicity, and GWP data.
ASHRAE, in collaboration with the United Nations Environment Programme (UNEP), has released an updated fact sheet that introduces new refrigerants with assigned B numbers and their safety classifications according to Standard 34. The document covers substances designated since 2010 and provides important technical data such as global warming potential (GWP), boiling points, and composition of blends. The purpose of the update is to provide HVACR professionals with standardized and up-to-date information on new refrigerants.
ASHRAE Standard 34 assigns designations to refrigerants in the format - and classifies them by toxicity and flammability. For example, "A1" means low toxicity and non-flammability, and "A2L" means low toxicity with low flammability. Zeotropic mixtures are assigned numbers in the R-4юх range, and azeotropic mixtures are assigned R-5xxx.
The new refrigerants include R-1233zd(Ε) (Α1, GWP 1, boiling point 18.1°C) and R-1336mzz(Z) (A1, GWP 2, boiling point 33.4°C), as well as low-potential mixtures such as R-444A (A2L, GWP 89) and R-451A (A2L, GWP 133). Flammable natural mixtures such as R-441A (AZ, GWP 5) and R-477A (AZ) are separately identified, which contributes to the industry's transition to more environmentally friendly solutions.
Standard 15 complements Standard 34 and establishes requirements for the safe design of refrigeration systems to prevent harm to people and property. It addresses hazards such as component failure, refrigerant leakage, toxic exposure, and poor ventilation.
“These refrigerant classifications are essential for engineers and system designers to make informed, safe decisions,” said Mark S. Owen, ASHRAE Director of Publications and Education.
The bulletin reflects the ongoing technical collaboration between ASHRAE and UNEP under a Memorandum of Understanding to advance current safety and environmental standards in HVACR.
ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) is an international professional association dedicated to advancing the heating, ventilation, air-conditioning, and refrigeration (HVAC&R) industry. Founded in 1894, ASHRAE has more than 50,000 members in 130 countries. ASHRAE develops standards, conducts research and training programs, and publishes technical guidelines that are widely used in construction and engineering. Learn more at official website.