340 On the Park: The First Residential Tower in the Midwest to receive a LEED Silver Certification uses Intellihot's water heating system. | Photo Credits: https://www.urbanrealestate.com
Version 5 or v5 is the latest version of LEED: a comprehensive framework for green buildings that enjoys global recognition. LEED v5 aims to drive deeper decarbonization for the building industry by recognizing efforts that lead to a higher impact on overall sustainability as well as building occupants’ quality of life. The US Green Buildings Council (USGBC) has opened LEED v5 for public comments till May 30, 2024. Here’s a summary of everything that’s new in LEED v5.
One of the key areas that LEED v5 focuses on is decarbonization, with one of its latest requirements introducing effective refrigerant management. Here’s everything you need to know.
According to The Carbon Almanac, alternative refrigerants are projected to save 43.5-50.5 gigatons of CO2 emissions.
Refrigerants are common components found in buildings’ heating and cooling devices. Most refrigerants (like the HFC-based R134a and R410a which are common in the industry) have a high global warming potential. Here’s an explanation of global warming potential:
“Refrigerants have a relatively low boiling point compared to water. Generally, if refrigerants are exposed to outdoor conditions, they will vaporize into the environment. Like carbon dioxide, these refrigerant vapors are considered “greenhouse gasses” and will tend to trap heat and induce a greenhouse effect in the atmosphere. In fact, HFCs – the de facto refrigerants in the industry today – may be thousands of times greater in global warming potential than carbon dioxide.” (Source)
Hence, using alternative refrigerants like the CO2- based R744 is crucial. R744 has a global warming potential of 1, compared to R134a’s GWP of 1430 and R410a’s GWP of 2088. In plain words, R134a has 1430 times the global warming potential of carbon dioxide, while R410a has 2088 times the global warming potential of carbon dioxide.
That is the reason LEED v5 seeks to incentivize the use of alternative refrigerants and effective refrigerant management that can decrease the impact of global warming and accelerate decarbonization.
One of the requirements for new construction projects under LEED v5 is titled “Fundamental Refrigerant Management” and it seeks to accelerate the phase-out of refrigerants with a high global warming potential and reduce refrigerant leakage into the atmosphere.
In order to comply with the requirements, LEED v5 suggests two options: not using any refrigerants in the project, or using refrigerants with a low global warming potential with sufficient refrigerant leak checks.
For instance, LEED v5 considers a Global Warming Potential (GWP) upper limit of 700 for heat pump water heaters. In fact, commonly used refrigerants like R410a have been prohibited by LEED v5’s guidelines. A complete list of the proposed GWP caps for this LEED v5 requirement can be found here.
Intellihot's Electron iE1 is the world's first tankless heat pump water heater. It uses the R744 refrigerant with a Global Warming Potential of just 1.
“The launch of LEED v5 underscores our unwavering commitment to our mission of fostering sustainable building practices that embrace principles of equity, health, biodiversity and resilience. Requirements within LEED v5, coupled with the federal government’s efforts to establish the new national definition of zero-emissions building, represent a pivotal moment in the built environment’s path toward decarbonization,” says Peter Templeton, president and CEO of USGBC.
Given the threat that refrigerants like R134a and R410a pose to the environment, the push for natural and alternative refrigerants is understandable. However, from a performance standpoint, it is also natural to wonder whether alternative refrigerants can be liable replacements. The good news is that several studies have shown alternative refrigerants to perform equally, and sometimes even better than commonly-used refrigerants.
For instance, the R744 refrigerant has better heat transfer characteristics as confirmed by multiple studies. It has demonstrated better performance in colder climates with lower pressure requirements for operation. This means that devices that use R744 won’t have noise issues due to vibration from high-pressure operation. Moreover, refrigerant leaks (which are now discouraged by LEED v5) are less likely to occur in low-pressure operation scenarios.
The results of these 3rd party research studies comparing the performance of R410a, R134a, and R744 in heat pump water heaters can be found in our whitepaper here.
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