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David Nemtzow
Building Technologies Office Director – US State Department of Energy

Chemicals commonly used to air condition buildings pose a significant threat to the global climate. Today, Secretary of State John Kerry is hosting foreign and environmental ministers in New York City – to coincide with the United Nations General Assembly – to voice support for an ambitious amendment to the Montreal Protocol to phase down the use of these dangerous chemicals, known as hydro fluoro carbons (HFCs). Phasing down HFCs – which can be hundreds to thousands of times more potent than carbon dioxide and can last for centuries when released into the atmosphere – could avoid up to 0.5°C of global warming by the end of the century. While reducing CO2 pollution is essential, gases such as HFCs are rapidly growing in use in air conditioning and refrigeration around the globe (by 2050, energy consumed for space cooling in developing nations alone may grow by 450% from 2010 levels as billions of people seek relief from high heat and humidity) which means that without action on HFCs, gains from cutting CO2 would be significantly undermined.

The Energy Department plays an important role in protecting the environment,  including by contributing  to worldwide negotiations to address the issue globally. Last fall, Secretary of Energy Ernest Moniz discussed the need to phase down HFCs under the Montreal Protocol. Last year in Dubai, countries agreed to work within the Montreal Protocol to an amendment in 2016 – and the follow up negotiations next month in Rwanda represent the last opportunity to fulfill the end-of-2016 commitment. However, many developing and hot weather countries still have reservations about how well alternatives to HFCs can perform compared to conventional refrigerants, especially in very hot climates. Led by my colleague, Antonio Bouza, the Energy Department’s Building Technologies Office (BTO) has been working with a research team at Oak Ridge National Laboratory (ORNL), led by Omar Abdelaziz, to assess how several low-global warming potential (low-GWP) alternative refrigerants perform under high temperature conditions of up to 131°F, and to see if they were up to the challenge. Last year we looked at the performance of alternative refrigerants in the mini-split air conditioners that are used ubiquitously worldwide. This year, we focused on performance in packaged rooftop unit air conditioners, given these units’ prevalence in low-rise commercial buildings. The evaluation program was advised by a panel of experts from Brazil, China, Egypt, India, Italy, Japan, Peru, Saudi Arabia, the U.S. and the United Nations.

Today, we’re releasing a report that summarizes the results of this evaluation program, based on rooftop units designed and manufactured in the developing world. The research at ORNL shows quite clearly that both R-22 and R-410A – two of today’s most common refrigerants – have several viable replacements, including ones that will give equivalent performance even under extreme ambient temperatures. Because alternatives  were tested without making any major equipment changes, researchers believe that their actual performance can be even better when used in air conditioners that are optimized for their unique properties.

This new study, like the one before it, provides the international community with solid evidence that viable replacements for HFC refrigerants can be used across building types and climate zones – including some of the most punishing ones – without significantly impacting unit energy efficiency or cooling capacity. The U.S. Energy Department is working on other fronts with industry partners and national labs to develop a new generation of air conditioning and heating technologies to revolutionize the industry by utilizing low- to zero-GWP innovations in advanced and non-vapor compression systems. Projects with the Energy Department’s office dedicated to building technologies, such as advancements in supermarket refrigeration, commercializing alternative    refrigerants,and developing the first electrochemical compressor for home water heaters are leading the way among existing technologies. At the same time, projects such as magnetocaloric cooling seek to leap-frog the status quo to new, zero-GWP refrigeration technologies.