3 Environmental Effects and Refrigerant Regulations

Two measures of environmental impact

Refrigerants move heat in cooling systems, but leaks and other releases can affect the atmosphere. Two distinct measures describe these effects: ozone-depletion potential (ODP) and global-warming potential (GWP). A refrigerant can have little or no effect on ozone while still contributing substantially to climate change.

Ozone depletion

The stratospheric ozone layer absorbs much of the Sun’s harmful ultraviolet radiation. Certain chemicals containing chlorine or bromine can reach the stratosphere, where sunlight releases atoms that destroy ozone through repeated chemical reactions.

Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) deplete ozone; CFCs generally have greater ODP. Hydrofluorocarbons (HFCs) contain no chlorine and do not deplete the ozone layer. However, many HFCs are powerful greenhouse gases, so replacing an ozone-depleting refrigerant with an HFC can solve one environmental problem while leaving another.

Global warming and system impacts

Global-warming potential (GWP) compares the heat-trapping effect of a greenhouse gas with that of the same mass of carbon dioxide over a specified period, commonly 100 years. Carbon dioxide is assigned a GWP of 1. A higher GWP means that a given mass of refrigerant released has a greater warming effect by this measure. For example, R-404A has a much higher GWP than carbon dioxide or propane (R-290).

GWP is not the only factor in a system’s climate impact. Leaks, refrigerant charge, system energy use, and refrigerant emissions during servicing and disposal also matter. Efficient equipment and good leak prevention can reduce impacts over the system’s life.

Regulations for refrigerants

The Montreal Protocol is an international agreement that phases out ozone-depleting substances. Its Kigali Amendment adds a phasedown of HFCs because of their climate impact.

In the United States, the Clean Air Act and EPA rules implement controls on ozone-depleting substances. The American Innovation and Manufacturing (AIM) Act provides for an HFC phasedown and restrictions on certain higher-GWP uses. The Significant New Alternatives Policy (SNAP) evaluates substitutes for ozone-depleting substances, including their environmental and safety risks.

Rules vary by refrigerant, equipment type, use, and date. Technicians and equipment owners must check the requirements that apply to their specific system.

Recovery and responsible handling

For stationary refrigeration and air-conditioning equipment, Section 608 prohibits intentional venting of ozone-depleting refrigerants and most substitutes during service, repair, or disposal. Required refrigerant must be recovered rather than deliberately released.

Recovered refrigerant may be recycled or, where required, reclaimed to the applicable purity standard. Section 608 also includes technician-certification, equipment, and recordkeeping requirements, as well as leak-repair requirements in specified cases.

Lower-GWP options and selection

Potential lower-GWP options have different operating and safety considerations:

• Carbon dioxide (R-744): Very low GWP, but systems operate at high pressures and require equipment designed for them.

• Ammonia (R-717): Very low climate impact, but toxic and subject to strict safety requirements.

• Hydrocarbons: Propane (R-290) and isobutane (R-600a) have low GWP but are flammable; approved uses and equipment safeguards are important.

• Hydrofluoroolefins (HFOs) and some blends: Often lower-GWP options than older HFCs, but suitability and environmental properties vary by product and application.

No refrigerant is automatically the best choice for every system. Selection must account for equipment design, applicable regulations, energy efficiency, performance, and hazards such as toxicity, flammability, and operating pressure. Never substitute a refrigerant unless the equipment and applicable rules allow it.

Applying the environmental and safety principles

CFCs and HCFCs can deplete ozone, while HFCs do not but many have high GWP. International agreements and U.S. regulations phase out or phase down these substances and control their use and release. Lower-GWP alternatives can reduce climate impacts, but each has application-specific performance and safety requirements. Proper recovery, leak prevention, and compliant servicing are essential for every refrigerant.