The U.S. Environmental Protection Agency (EPA) will receive comments until September 12 on a new proposal under its Significant New Alternatives Policy (SNAP) program to list HFO-1234yf, HFC-32 and HFO blends as acceptable, subject to use conditions, for new chiller equipment, which includes residential and light commercial air conditioning and heat pumps as well as residential and non-residential dehumidifiers.

Comments can be submitted up to and including September 12 here.

According to Proposed Rules in the Federal Register, posted July 28, the EPA has proposed listing HFO–1234yf, R454A, R454B, and R454C as acceptable, subject to use conditions, for use in new chiller equipment.

It also proposed listing HFC–32 and R452B as acceptable, subject to use conditions, for use in new rotary and scroll chiller equipment, for chillers used in comfort cooling, including both commercial and industrial process AC.

The agency also proposed, for residential and light commercial AC and heat pumps, listing HFC–32 as acceptable, subject to use conditions, for use in new self-contained room ACs and heat pumps.

R452B, R454A, R454B, and R454C are HFO/HFC blends. For example, R454B consists of 68.9% HFC-32 and 31.1% HFO-1234yf. R454B has a 100-year GWP of 490 and a 20-year GWP of 1,700.

HFC-32 has a 100-year GWP of 704 and a 20-year GWP of 2,530. HFC-32 has an atmospheric lifetime of only 5.4 years, making a 20-year GWP more applicable than a 100-year GWP, according to many HVAC&R stakeholders.

Conversion to TFA

HFO-1234yf has a GWP under 1. However, when it leaks into the atmosphere, 100% of HFO-1234yf photo oxidizes, in only 10-14 days, into trifluoroacetic acid (TFA). TFA then descends in rainfall to Earth, where, as an extremely durable chemical, it accumulates mostly in water bodies, including rivers, streams, lakes and wetlands.

While not currently regulated, the TFA is collecting in the environment, according to a number of recent studies, which largely attribute this to expanding emissions of HFO-1234yf.  

In Germany, where a host of TFA studies have been conducted, the German Environment Agency (UBA) has set a human health “orientation value” limit of 60 µg/L for TFA in drinking water and a “precautionary measure” of 10 µg/L. The concentration levels of TFA in the environment have begun to approach – or exceed – those levels in some studies.

Both TFA and HFO-1234yf fall under the definition of PFAS (per- and polyfluoroalkyl substances)established by the OECD (Organisation for Economic Co-operation and Development) and used by scientists around the world.

The EPA does not currently use the OECD definition of PFAS. But five European countries, adopting the OECD definition, announced last year their intention to submit a joint proposal to restrict some HFC and HFO refrigerants and TFA as PFAS under the EU’s REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulation. The European Chemicals Agency (ECHA) is expected to take up the proposal next January.

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