HVACR systems have evolved significantly in recent times. However, in the years to come, the technology will undergo greater, revolutionary changes. The broad, concurrent goals of increasing energy efficiency and mitigating the emissions of greenhouse gasses require producers of refrigerants used in HVACR systems to develop new offerings. This subsequently requires HVACR equipment and component manufacturers to redesign their portfolios and to use refrigerant gasses that currently may be unfamiliar to the code community. Equipment manufacturers are trying to plan for the future as best they can, recognizing that the international community has yet to decide how to phase down the use of some of today’s common refrigerants and that the US Environmental Protection Agency (EPA) is in the midst of regulatory actions that will shape the future of refrigerants in the US.
The warnings have been clear: 2014 was the warmest year in recorded history, the past decade was the warmest decade on record, and the 10 warmest years ever have all occurred since 1998. This notable change in temperature in combination with the devastation of recent super storms – both hurricanes and blizzards –and the record drought in the western US put global policy makers under pressure to reduce emissions of global warming gasses.
HVACR engineers have long realized that, as more restrictions are placed on traditional refrigerants, they will have to design their equipment to operate with refrigerants that have much higher pressures or could be more flammable.
Refrigerants used for air-conditioning and refrigeration have been among the most potent global warming gasses in terms of their global warming potential (GWP). When CFCs were banned because of their ozone-depleting qualities, the world also eliminated some of the worst greenhouse gasses, some of them more than 10,000 times more potent than CO2. And although the primary refrigerants being used today are more environmentally benign than CFCs, they still can have a GWP a few thousand times that of the CO2 benchmark. EPA, as part of the Obama Administration’s Climate Action Plan, is issuing a series of regulations to begin phasing down the use of today’s high-GWP refrigerants. The Significant New Alternatives Policy, also known as SNAP, has begun to ban the use of certain high-GWP refrigerants and allow the use of lower-GWP alternatives. This includes familiar chemicals like propane and ethane, as well as synthetic chemicals developed especially for refrigeration and air-conditioning applications.
The US is pushing for global action on higher-GWP gases, but already lags behind Europe, where the F-Gas rule – that went into effect at the beginning of 2015 – already bans the use of some high-GWP refrigerants and will phase down (or phase out) the use of others in the coming years, including some of the refrigerants currently used for cooling and heating equipment.
In fact, all of the practical ways of providing cooling and refrigeration today will depend on refrigerants that have some level of flammability and/or are operated at elevated pressures.
Meanwhile, international negotiators are getting closer to a global agreement on the phasedown of higher-GWP refrigerants. This agreement, when implemented, will put more pressure on global HVACR equipment manufacturers to seek new refrigerant solutions, most of which will have some flammable properties.
Challenges and Impact on Fire and Safety Codes
HVACR engineers have long realized that, as more restrictions are placed on traditional refrigerants, they will have to design their equipment to operate with refrigerants that have much higher pressures or could be more flammable. The same atomic bonds that make today’s refrigerants stable and non-flammable also make them long-lived, thus keeping them in the atmosphere for years, contributing to the dynamics of climate change.
In fact, all of the practical ways of providing cooling and refrigeration today will depend on refrigerants that have some level of flammability and/or are operated at elevated pressures. This includes refrigerants in large chillers, rooftop systems, residential air conditioning and heat pumps, as well as commercial refrigeration equipment, including supermarkets. Tomorrow’s building and fire codes will have to address this technological evolution.
R-32, a 2L mildly flammable refrigerant, is being used by Japanese manufacturers in mini-split air conditioners and heat pumps, which are more common in the rest of the world than they are in North America.
Path Forward with ASHRAE and ICC
The American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) has long been recognized as an expert in refrigerant safety. ASHRAE Standard 34, Designation and Safety Classification of Refrigerants, assigns each refrigerant into a safety category and ASHRAE Standard 15, Safety Code for Mechanical Refrigeration, dictates how that refrigerant shall be used in a system. The ICC codes reference the ASHRAE standards.
ASHRAE 34 has typically divided refrigerant gasses into one of three flammability categories:
1 – Non-flammable
2 – Flammable
3 – Highly flammable
Further, ASHRAE 34 subdivides its “Flammable” refrigerants category into “Flammable” and “Mildly Flammable,” designated as 2L. (Refrigerants are further divided in high toxicity (B) or low (A), but that won’t be discussed here.) To be defined as “Highly Flammable,” refrigerants have a heat of combustion greater than 19,000 J/kg and a lower flammability limit (LFL) under 3.5 percent by volume in air. “Flammable” refrigerants have a heat of combustion less than 19,000 J/kg and an LFL greater than 3.5 percent.
The further breakdown of 2L refrigerants is based upon their burning velocity, with 2L refrigerants having a flame propagation speed less than 10cm/sec. Practically speaking, a 2L refrigerant can be thought as one that has a higher LFL, is difficult to ignite and, once ignited, has trouble sustaining a flame. It is, however, still flammable.
Most of the new refrigerants either now entering the market or being considered for future use are A2L or A3 substances.
ASHRAE 15 is currently being updated to include 2L refrigerants. It also is being reorganized as Standards 15.1, a commercial applications standard, and 15.2, a residential applications standard. These are expected to be submitted for consideration for the 2021 edition of the ICC Code. For this to happen, ASHRAE will have to complete the draft standards, receive and act on public comments and complete their approval process before the end of 2017 in order to be ready for code submittals by January 2018.
Success of Products/Solutions Available
There is a notable safety record for flammable refrigerants, mostly outside of North America. It is interesting to note that early refrigeration equipment in the US used refrigerants that were both toxic and flammable.
As part of its F-gas regulation, the EU banned the use of refrigerants with a GWP greater than 150 for domestic refrigerators, which, in effect, dictates the use of a hydrocarbon refrigerant. It is estimated that there are well over 1 billion hydrocarbon-based domestic refrigerators in operation worldwide with 100 million more being produced annually.1
Even in somewhat larger refrigeration units, hydrocarbon refrigerants have an excellent track record. This includes more than 20 million vending machines and bottle coolers in operation worldwide. To date, there have been no reports of fire or injury due to these machines.
Even for air-conditioning, where larger refrigerant charges may be required, new refrigerants are working safely. R-32, a 2L mildly flammable refrigerant, is being used by Japanese manufacturers in mini-split air conditioners and heat pumps, which are more common in the rest of the world than they are in North America. In fact, more than 8 million air-conditioning units using R-32 are estimated to have been installed worldwide.
Safety standards used in Europe already address flammable refrigerants, including:
- ISO 5149:2014. Mechanical refrigerating systems used for cooling and heating: Safety requirements – this revision includes requirements for new classifications of low flammability (2L) refrigerants. It puts an emphasis on minimizing refrigerant leakage and monitoring leaks.
- IEC 60335-2-40, 5th edition. Household and similar electrical appliances-Safety: Particular requirements for electrical heat pumps, and-conditioners and humidifiers.
Need for industry Engagement / Collaboration
Industry has already started planning for a world in which flammable refrigerants will be the norm. The Refrigerant Codes and Standards Task Force is a partnership of equipment manufacturers, refrigerant producers, retailers, standards developers, government organizations and NGOs who have the common aim of educating fire marshals and building code officials about the need for new refrigerants and the flammability research that has been conducted, and to bring to their attention the positive safety record of millions of pieces of equipment in the field.
Together, these organizations look forward to engaging with the fire and building code communities, so that tomorrow’s efficient and environmentally friendly systems can be installed safely throughout North America as they have been around the world.
1) UN TEAP Task Force Report, May 2014
Mark Menzer is director of public affairs for Danfoss.
Rusty Tharp is director of regulatory affairs for Daikin.
ED.NOTE: The authors' views on climate change do not necessarily reflect those of the editors of ContractingBusiness.com.