“Mechanical refrigeration based on the vapor compression cycle was first demonstrated in the 1830s and, for the next century, a broad range of substances were used; these included toxic compounds… such as ammonia.”

ASHRAE, Refrigerants and their Responsible Use

Ammonia (R-717) is a refrigerant option for certain applications and locations. Ammonia is a colorless gas with a very sharp odor. Ammonia has a B2L safety classification (“higher toxicity, lower flammability”). In the instance of an ammonia leak or discharge, vapors are highly toxic and harmful to humans, food, and aquatic life. While ammonia can be produced naturally by decomposition of animal waste, the ammonia used industrially is produced by a chemical process and is in fact synthetic.

Ammonia was first used in the 1800s before safety concerns curtailed its usage.1 It has been used as a viable low GWP option but requires careful management as accidental releases can be harmful or fatal.

Switching to ammonia in existing locations requires more complex, costly, large-scale renovations and new safety systems and equipment, as well as expanded personnel protection measures. The greater complexity can drive cost and require more downtime for retailers or other end-users. For this reason, ammonia systems are typically only developed as part of new builds.