Commercial refrigeration stakeholders have been closely monitoring regulatory efforts to phase down the use of high-global warming potential (GWP) hydrofluorocarbon (HFC) refrigerants. The unsettled regulatory climate has made it difficult for food retail companies to plan for compliance and select next-generation refrigeration strategies. But now it appears that the regulatory picture is coming into clearer focus. Many companies have already begun their lower-GWP refrigerant transition and seek regulatory guidance to help inform their long-term refrigerant choices and implement their sustainability goals.
For several years, the governing bodies that regulate the safe use of refrigerants in the U.S. have been evaluating the prospect of increasing charge limits in the flammable A3 refrigerant propane (R-290) and an emerging class of mildly flammable A2L refrigerants. In 2021, the Underwriters Laboratories (UL) approved the second edition of its UL 60335-2-89 standard, which included higher charge limits that would expand the potential uses of R-290 and A2Ls in commercial refrigeration.
R-290 charge limit increases
With a long-held maximum charge limit of 150g, R-290 has primarily been used in smaller, self-contained units that don’t need large refrigeration loads. Designing larger-capacity, R-290 based refrigeration equipment has required the use of multiple R-290 based compressors or condensing units.
The updated UL standard raises the charge limits on these commercial stand-alone displays based on whether they have an open or closed design:
• 500g maximum charge limit in open appliances (without doors)
• 300g maximum charge limit in closed appliances (with doors or drawers)
From an application design perspective, these higher charge limits will help to increase system capacities while capitalizing on R-290’s high efficiency and low-GWP rating (GWP = 3).
Ensuring the safe use of A2L refrigerants
Mildly flammable A2L refrigerants have also been identified as low-GWP alternatives for complying with emerging refrigerant regulations. Because of their potential flammability, to date A2L refrigerants have been used globally in relatively small refrigeration architectures, such as: self-contained systems, indoor/outdoor condensing units (OCUs) and distributed systems.
Per the recently updated UL 60335-2-89 safety standard, new A2L charge limit guidelines have been established for self-contained and remote refrigeration systems. For self-contained equipment, charge limits are determined on whether equipment is open or has doors or drawers. Degrees of flammability will vary among different A2L refrigerants, so it’s important to calculate charge limits based on the specific A2L characteristics.
For example, since R-454C has a lower flammability limit (LFL) of 0.291 kg/m3:
• A closed-door case can be charged with up to 2.33 kg (5.1 lbs.) of R-454C.
• An open case with R-454C can be charged with up to 3.78 kg (8.3 lbs.) of R-454C.
In remote or field-erected systems, UL 60335-2-89 supports R-454C charge sizes up to 75.7 kg (166 lbs.) per circuit.
Per the UL 60335-2-89 standard, remote A2L systems must be designed with requisite safety strategies and mitigation measures to keep gas concentrations below flammable thresholds. This includes the ability to detect refrigerant leaks at various points of the refrigeration circuit — from the compressor to the condensing unit to the case — and then take immediate action to mitigate flammability risks. In human comfort applications, similar UL standards are also in place.
Safety standard updates set the stage for wider approvals
The UL 60335-2-89 second edition update is only the first step in a larger series of regulatory approvals needed to enable higher charges of R-290 and the use of A2Ls in U.S. commercial refrigeration. The following supporting regulatory and policy changes will also need to be approved:
• EPA Significant New Alternatives Policy (SNAP) approval of specific A2L refrigerants and increased R-290 charge limits
• ASHRAE 15 safety standard update for refrigeration systems
• Model code updates in the upcoming code revision cycle, such as: Uniform Mechanical Code (UMC), International Mechanical Code (IMC) and International Fire Code (IFC)
• State and local building code updates
Industry stakeholders are optimistic that the ASHRAE 15 update and EPA SNAP approvals (for at least some A2Ls) will yet take place in 2022. Although the next model code update is planned for 2024, select states have legislated or adopted provisions of the safety standards directly into their building code updates to allow for the use of all EPA-approved substitutes. Thus, our industry could begin to see some A2Ls used in late 2022 or early 2023, with more widespread use expected in 2024. In the meantime, installing an A2L-based refrigeration strategy would typically require the approval of local authorities having jurisdiction (AHJ), such as fire marshals and/or building inspectors.
When considering the regulatory uncertainty in the U.S., it is easy to forget that the Montreal Protocol has been evaluating the global warming potential of HFCs for over a decade. In 2016, 197 countries met in Kigali, Rwanda, and agreed on a global proposal to phase down HFCs. The Kigali Amendment required ratification from at least 20 countries to take effect. To date, 130 countries (including the E.U. Member States, but not including the U.S.) have ratified it. As such, it took effect for participating countries on January 1, 2019.
In the U.S., the Kigali Amendment currently sits with the Senate for possible ratification. Many industry stakeholders believe that doing so would be beneficial to our current state of regulatory and economic affairs. Ratification could help to establish a framework for future refrigerant regulations that would provide the certainty needed to help the industry and regulatory bodies move forward with a unified approach.
According to an economic study co-sponsored by AHRI and the Alliance for Responsible Atmospheric Policy, ratifying the amendment could create up to 33,000 jobs in the manufacturing sector by 2027 and is expected to have a positive impact on the U.S. economy. For these reasons, many in the industry are in favor of ratification and have demonstrated this through letters of support to the Senate and the White House.
The American Innovation & Manufacturing Act (AIM Act) was signed into law in 2020, granting the federal government the authority to regulate HFC refrigerants in three primary ways via the Environmental Protection Agency (EPA).
Note: Even if the leak repair and maintenance requirements of Section 608 are currently not enforced for HFCs, an effective leak repair and maintenance program is still generally recognized as an industry best practice. Other beneficial provisions of Section 608 — including the certified technician program and the refrigerant recovery and reclamation rules — are still in effect.
The EPA has faced challenges relative to regulating HFC refrigerants over the last five years. In 2015/16, they finalized the SNAP 20/21 rulemaking, designating several high GWP refrigerants unacceptable for use across multiple commercial refrigeration end uses. Litigation ensued, challenging the EPA’s authority to regulate non-ozone-depleting substances under the Clean Air Act (CAA). In 2017, the court agreed with the plaintiffs and partially vacated the SNAP rules that required those users already moving out of ozone-depleting substances to shift again to lower-GWP refrigerants. In response to the 2017 court ruling, the EPA stated they would not enforce HFC provisions for SNAP 20/21 at the federal level and has rolled back other HFC-related regulations. In particular, they have excluded HFCs from the leak repair and maintenance requirements for stationary refrigeration equipment, otherwise known as Section 608 of the CAA.
Even if the leak repair and maintenance requirements of Section 608 are no longer enforced for HFC systems, an effective leak repair and maintenance program is still generally recognized as an industry best practice. Other beneficial provisions of Section 608 — including the certified technician program and the refrigerant recovery and reclamation rules — are still in effect.
The California Air Resources Board (CARB) continues to lead the way on the HFC phasedown in the U.S. After several years of collaboration with state and HVACR industry stakeholders, CARB’s proposed rulemaking became final in late 2021 and went into effect on Jan. 1, 2022. This rule establishes HFC phasedown requirements for new facilities and includes a company-wide provision for food retailers operating with a fleet of existing stores within California.
New facilities — Installation of new refrigeration systems containing more than 50 pounds of refrigerant are required to use refrigerants with less than 150 GWP.
Existing facilities — Installation of new systems are subject to company-wide, fleet GWP reduction targets by 2030, as compared to their 2019 baselines. CARB offers two paths to compliance for new systems in existing facilities:
Refrigeration equipment under 50 lbs of charge will still be required to follow SNAP 20/21 per state law.
Although the AIM Act permits individual states to create their own environmental regulations — such as those pursued by U.S. Climate Alliance states — many are awaiting federal guidance for the use of refrigerants in commercial refrigeration. Industry organizations — such as the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) and the Natural Resources Defense Council (NRDC) — and stakeholders have asked for states to be consistent in their approaches. Most would prefer that our industry adopt a unified federal approach, rather than managing a patchwork of state-led initiatives.
With California taking a leadership role on environmental regulations, it’s very likely that other states will adopt a similar (if not identical) approach. In 2017, a coalition of 16 states and Puerto Rico emerged to form the U.S. Climate Alliance, with a shared commitment of reducing SLCPs and HFCs. Since then, the Alliance has grown to 25 members — comprising more than 55 percent of the U.S. population and an $11.7 trillion economy; several of its states have announced plans to follow California’s lead on HFC phase-downs.
Industry advocates, including the Air-conditioning Heating and Refrigeration Institute (AHRI) and the NRDC, have asked for states to be consistent in their approach to adopting CARB’s rules.
Refrigerants are only one factor in the regulatory equation affecting HVACR industry; it is also dealing with energy mandates by the DOE. While these were introduced in 2014, they have evolved to present significant implications across three classes of commercial refrigeration equipment.
Commercial Refrigeration Equipment (CRE). Since the enforcement date of March 2017, new CRE have been subject to 20-86% energy reductions, depending on the specific class of equipment. Compliance equations are factored according to the unit’s daily energy consumption (kWh/24-hour) and its total display area.
Automatic Commercial Ice Makers (ACIM). As of January 2018, new ACIMs must achieve 5-25% energy reductions, as measured in kWh/100 lb. of ice. Again, each equipment class has a specific equation to measure compliance, so OEMs must be certain of their particular class requirements.
Walk-in Coolers and Freezers (WICF). WICF manufacturers are looking at a 2020 enforcement date to reduce energy consumption by 30-37%. These reductions are measured according to the AHRI-1250 annual walk-in efficiency factor (AWEF) standard. It is worth noting that while the original benchmark set for this standard has been reduced through persistent industry negotiations, it still represents a significant energy reduction target for WICF equipment.
