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New HVAC refrigerants: Could CO2 Replace R-22?

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Last Updated on January 17, 2020

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Technician adding HVAC refrigerants to air conditioning unit

If you’ve been following our HVAC blog articles, you probably notice that they’re usually very practical. We offer guidance about issues that are on your mind and provide information that’s immediately helpful. Once in a while, though, we like to talk about something just because we think it’s interesting and enlightening. This blog about new HVAC refrigerants is one of those posts. We hope you’ll find it interesting and enlightening, too!

The true story behind HVAC refrigerants

Refrigeration was originally invented because we wanted to make our food last longer and prevent waste from spoilage. We learned that keeping it cool accomplished that goal. Isn’t it ironic that the chemical HVAC refrigerants we developed to chill our food (as well as cool our living and working spaces) are some of the worst contributors to the greenhouse effect and global warming? That’s right: as we chill our food to preserve it, we’re heating up our planet and destroying it.

The impact of older HVAC refrigerants

The environmental dangers of HVAC refrigerants have been known for decades. The industry standard for many years was Freon (also known as R-22), a hydrochlorofluorocarbon gas, or HCFC. Back in the 1970s it was discovered that HCFC gases were quickly depleting the Earth’s ozone layer. In international environmental treaty called the Montreal Protocol called for a worldwide phase-out of HCFC HVAC refrigerants by the year 2020. That’s why only old air conditioning systems still use Freon today—it’s expensive and won’t be around much longer.

As a result, new HVAC refrigerants called HFCs (also known as F-gases) were developed that are non-flammable, recyclable, energy-efficient and less damaging to the ozone layer. However, it turns out that they hang around in the atmosphere for hundreds and even thousands of years, intensifying and speeding up the process of global warming.

More and more countries globally are joining the movement to phase-down the use of R-22 and HFC-type HVAC refrigerants, and some have enacted outright bans. As the world looks for ways to decrease the environmental impact of refrigeration and air conditioning equipment, some are exploring the use of natural HVAC refrigerants, most commonly carbon dioxide or CO2, as a potential solution.

Exploring natural HVAC refrigerants

Actually, it would be more accurate to say that some are exploring a return to natural HVAC refrigerants. When refrigeration was first developed, carbon dioxide and ammonia were among the first popular refrigerants. Unfortunately, ammonia is toxic and its use today is strictly regulated. Carbon dioxide is problematic because it requires both high pressures and high compressor temperatures. But since natural HVAC refrigerants like these have little to no ozone depletion potential (ODP) or global warming potential (GWP), they are once again being explored as viable options.

Could carbon dioxide be a viable option for HVAC refrigerants?

It turns out that the previous liabilities of carbon dioxide, the high pressure and temperature requirement, can be an advantage. The high pressure allows for a higher density but lower volume of refrigerant, which means that systems can be smaller and require less power consumption. The high heat output has led some companies to begin using CO2 in heat pumps. In fact, the Japanese company Mayekawa has developed several commercial CO2-based heat pumps that are already being sold in North America.

Carbon dioxide has been found to have a number of characteristics that make it a promising choice for environmentally-friendly HVAC refrigerants:

  • An ODP level of 0, and a GWP level of 1
  • Lower cost than HFC-type HVAC refrigerants
  • Non-toxic and non-flammable
  • Odorless
  • Requires lower amounts of HVAC refrigerant (“refrigerant charge”) than HFC refrigerants
  • Performs better than HFCs with less power usage

In other parts of the world, where HFCs are being banned outright, CO2-based refrigeration systems are being adopted more quickly than in the United States. But as the need to reduce our carbon footprint becomes more urgent, we will certainly see the development of more commercial refrigeration and HVAC equipment designed for CO2 use here in the U.S.

Related articles:
HVAC System Maintenance Just Got a Whole Lot Greener
The Future of Air Conditioning: It’s All About Efficiency and Comfort

At Arista, we understand the importance of keeping up with the emerging developments in our industry. We’re committed to understanding the performance, safety and economic impacts of new technology, so we can help you make good decisions about your capital equipment purchases.

Speaking of good decisions about your equipment purchases, are you getting this benefit from your HVAC company? Do they help you to understand the available technology options and what could best work for you? How about planning for equipment obsolescence and pro-active replacement of older components so you can avoid downtime? If not, it might be time to think about moving to an HVAC company that understands your needs and your business, and acts as a partner to help you get the most from your systems. To learn more about the best way to make a change, read our helpful guide to Contract Confidence: Transitioning to a New HVAC Service Provider.

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