The May 2025 UNEP/ASHRAE factsheet outlines new refrigerant numbers and safety classifications under ANSI/ASHRAE Standards 34 and 15, including flammability, toxicity, and GWP data.
ASHRAE has released an updated refrigerant factsheet in collaboration with UNEP, detailing newly designated refrigerants and their safety classifications under Standard 34. The document includes refrigerants assigned an R-number from 2010 onward and presents critical data such as global warming potential (GWP), boiling points, and chemical compositions. These updates aim to provide HVACR professionals with standardized references for emerging refrigerants.
ASHRAE Standard 34 designates refrigerants with an R- followed by a number and categorizes them by toxicity and flammability. For example, "A1" indicates low toxicity and no flame propagation, while "A2L" represents lower toxicity with mild flammability. Zeotropic blends are numbered in the R-4xxx range and azeotropes in the R-5xxx series.
New refrigerants include compounds such as R-1233zd(E) (A1, GWP 1, boiling point 64.6°F / 18.1°C) and R-1336mzz(Z) (A1, GWP 2, boiling point 91.4°F / 33.4°C), along with low-GWP blends like R-444A (A2L, GWP 89) and R-451A (A2L, GWP 133). The list also highlights flammable natural refrigerant mixtures such as R-441A (A3, GWP 5) and R-477A (A3), supporting the industry's transition to environmentally safer options.
Standard 15 complements Standard 34 by setting safety guidelines for system design to protect people and property. It addresses risks such as pressure rupture, refrigerant leakage, and toxic exposure, especially in poorly ventilated areas.
"These refrigerant classifications are essential for engineers and system designers to make informed, compliant choices," said Mark S. Owen, Director of Publications and Education at ASHRAE.
The factsheet also reflects ongoing technical cooperation between ASHRAE and UNEP under their Memorandum of Understanding, ensuring the HVACR industry is aligned with current environmental and safety standards.
