A global agreement to phase down the use of potent greenhouse gas refrigerants and replace them with climate-friendly alternatives leaned on multiple ORNL studies.
In a landmark decision, climate leaders from more than 190 countries agreed to amend the Montreal Protocol to discontinue producing and consuming high-global warming hydrofluorocarbons, or HFCs. HFCs used in today鈥檚 air conditioners and refrigerators were first introduced as a way to combat depletion of the ozone layer. Researchers now know that although HFCs are friendly to the ozone layer, they contribute to global warming.
A series of DOE-funded reports co-authored by ORNL and Navigant Consulting investigated the performance of HFC alternatives such as hydrofluoroolefin mixtures and hydrocarbons. The researchers鈥� latest study evaluated the energy efficiency and cooling capacity of nine low-global warming potential options in roof top and small residential air conditioners in simulated temperature and climate conditions similar to the Middle East and parts of Asia and North Africa.
鈥淚t was thought that the soaring temperatures of 100-130 degrees Fahrenheit can degrade air-conditioner performance when using the alternative refrigerants,鈥� ORNL鈥檚 Omar Abdelaziz said. 鈥淥ur research demonstrated that similar or better energy efficiency and cooling capacity could be achieved with other low-global warming potential refrigerants compared to the baseline HFC refrigerants.鈥�
Abdelaziz, who leads ORNL鈥檚 High-Ambient-Temperature Evaluation Program for Low Global Warming Potential Refrigerants, presented results of 鈥溾€� to Montreal Protocol representatives during a workshop in Vienna. The State Department, White House and DOE referenced the report鈥檚 key findings that influenced the protocol鈥檚 amendment.
Phasing down HFCs could avoid up to 0.5 degrees Celsius of global warming by the end of the century, contributing to the Paris Agreement goal to limit global temperature rise to well below 2 degrees Celsius.
The ORNL reports evaluated multiple refrigerant alternatives for and for , or ductless, air conditioners.