This month’s editorial calendar focuses on “refrigerants in transition,” so I thought I’d offer up my thoughts on refrigerants and their impact on ozone-depleting potential (ODP) and global warming potential (GWP).
I am familiar with ASHRAE’s position document on refrigerants and its responsible use, but I was unaware that Air-Conditioning, Heating, and Refrigeration Institute (AHRI) formed a refrigerant transition taskforce to address every step of the supply chain in the safe refrigerant transition to low-GWP refrigerants. The organization also addressed refrigerants, in general, relative to their handling, application, management, and disposal. AHRI has drawn upon “fact sheets,” such as, “A Guide to the Safe Refrigerant Transition” and its discussion on the changing world of hydrofluorocarbon (HFC) regulations and the chemical physical and environmental properties of a relatively new class of A2L refrigerants. This A2L grouping of refrigerants has lower toxicity and flammability when compared with A2 or A3 refrigerants. Class A1 refrigerants are noted to offer “no flame propagation,” but they are toxic.
The HVAC industry has come a long way since the 1989 Montreal Protocol, where concerns directly affecting our environment became well-documented and set a global agreement mandate to protect the stratospheric ozone layer by phasing out the production and consumption of ozone-depleting substances (ODS). Since that time, refrigeration equipment manufacturers have moved away from the now banned R-11 and R-12 to newer refrigerants. Producers are now setting their sights on a new class of next-generation refrigerants grouped under the A2L class.
One refrigerant that is commonly overlooked in the HVAC industry is ammonia, which does not appear to affect global warming or cause ozone depletion. ASHRAE does recognize ammonia in three of its four handbooks (Refrigeration, Fundamentals, and HVAC Applications), but its application is more in the process cooling and freezing industries. Ammonia is toxic and flammable but, when engineered correctly in refrigeration systems, it is safe.
Today, design engineers, as well as equipment manufacturers, must take a renewed account for their projects and the equipment being engineered. Performance, safety, reliability, environmental acceptability, and economics can each influence an engineer’s HVAC application. All too often, the selection of the optimum refrigerant for the HVAC application bypasses the aforementioned points of discussion. Seldom do HVAC designers rely on equipment manufacturers to provide information regarding their projects' refrigeration systems, so the decision for which refrigerant to use is determined by the equipment manufacturer representative who calls on the consulting engineer(s).
Refrigeration for process cooling can be considered a boutique engineering initiative. In cooler-freezer applications (e.g., frozen food plant), the design engineer more often than not will be the decision-maker for the five points of a refrigerant: performance, safety, reliability, environmental acceptability, and economics. Here, the equipment manufacturer will have less influence, and the application result may often be the use of ammonia.
I believe consulting engineers for commercial HVAC applications need to follow the lead of industry consulting engineers if we are to achieve the goal of stopping global warming and truly begin to protect the environment.