Utility Partners

Those looking for help in implementing a leak detection and mitigation program may not have to look further than their local utilities. While decarbonization efforts have led utilities to stick primarily to electrification and weatherization programs, they are now starting to look at ways to support refrigerant leak mitigation in order to further reduce emissions, said Ali White, senior engineering consultant at VEIC in Winooski, Vermont.

“We made the case in Vermont and elsewhere that refrigerants are 4% to 6% of total state emissions, and they're typically lumped into industrial processes rather than building emissions,” she said. “As we all know, they are a source of emissions in buildings, so they really are the low-hanging fruit of greenhouse gases that utility efficiency programs that are switching to decarbonization metrics could be going after.”

White added that in Vermont, they found energy savings to be associated with most of their refrigerant management measures. By combining the energy and non-energy savings, an ideal bridge was created for utilities to go from strictly looking at kilowatt-hour savings to broadening that to greenhouse gas savings as well.

In Vermont, the refrigerant management program took a four-pronged approach:

1. Proactive refrigerant leak detection and repair;
2. Refrigerant retrofits to lower-GWP refrigerants;
3. Natural refrigerant systems, where applicable; and
4. Reduced system charge size, either through installing a glycol loop or designing systems to have a smaller refrigerant charge.

White said that this approach was implemented during several pilot programs, which relied on permanent leak detection systems and/or significant submetering in individual grocery stores to gather data. The results of the leak detection and repair program were encouraging, with 50 projects being completed between 2019 and 2021.

“The projects add a lot of non-energy value to both contractors and end users,” said White. “The total carbon savings impact per year was 5.4 million pounds CO₂e (2,450 metric tons), and the average leak reduction was 12%. That was through a combination of large custom storewide audits and permanent leak detection systems and also a smaller program geared towards small and medium business customers.”

Average annual estimated energy savings per project was 25,000 kWh, or $2,500 at $0.10 kWh.

For end users, leak reduction programs are particularly beneficial, said White. For example, equipment reliability can be improved, as shown by meter data on a compressor rack system that indicated a low refrigerant charge can lead to short cycling of the compressors. That can reduce equipment longevity and reliability, which can lead to compressors going down and an overall decrease in system resiliency.

Leaky systems can also cause product quality to suffer, even if they’re regularly topped off, said White. That’s because refrigerant leaks can cause cases to warm, leading to poor product quality. Fixing leaky systems can also improve energy efficiency.

“We have some good meter data, especially on smaller condensing units that experienced refrigerant leaks,” she said. “We were able to see spikes in energy consumption and the effects on different operating conditions and warming box temperatures at that small scale.”

Then there is the anecdotal data from end users, who say that permanent leak detection systems have prevented catastrophic leak events, said White.

“Similarly, we have customers who said leak rates were keeping them up at night,” she said. “With the installation of a permanent leak detection system, which combined high-quality equipment with trained technicians able to identify leaks, they say it has just made a huge difference in that store's resiliency.”

Best Practices

Leak detection is obviously a large part of a leak management program, and in addition to employing some kind of leak detection system (see sidebar), it should include best practices, such as conducting a refrigerant inventory. This lets everyone know how much refrigerant the facilities have, as well as where it is located. It is not good enough to know that there are 10,000 pounds of refrigerant spread across all the stores, said Agustin Cardona Chin, product manager at Emerson Commercial and Residential Solutions; instead, it’s better to know in more detail about where it’s located and being used.

“Also keep track of refrigerant usage,” he said. “That means that you have good recordkeeping, and you're continuously updating information. That lets you know where your refrigerant is being consumed and what your biggest offenders are. Also, create a refrigerant management plan that has a leak detection policy and procedures in place to meet regulatory requirements. Don’t just pay lip service to this.”

Another best practice is to work toward lowering the refrigerant leak rate by repairing leaks. “Try to fix them as quickly as possible, and don't just live with them,” said Chin. “Don't top off the refrigerant as you're experiencing leaks. Have a zero tolerance policy for leaks. Detect them through inventories or by using your available technology, such as fixed and handheld detectors. Also conduct periodic walkthroughs to see whether cases are leaking.”

Leaks can also be prevented by updating equipment.

“There comes a point when it’s not feasible to keep repairing equipment, especially as refrigerant costs go up,” said Chin. “Do an ROI analysis to see if it's time to replace the equipment. Track the performance to see if there’s more cycling, more electricity usage that might be an indication that there is bad equipment somewhere that's leaking.”

Finally, set company-wide goals by committing to reducing refrigerant usage by a certain percentage. “Make that clear to everybody in the group that this is what you're working towards, and have that become an objective — something reachable that people can work towards,” said Chin. “That will go a long way towards helping reduce your leak rate.”