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Why volume is also an important factor when choosing the most sustainable refrigerant for the long term in the wake of the AIM Act phasedown.

Trying to choose the best refrigerant in compliance with the AIM Act HFC phasedown can be a daunting process. On the one hand, GWP seems like the best guide. It’s simple, right, lowest is best? But what are we missing if we just choose our refrigerants based on a low GWP number? This article will help you explore everything you should consider when choosing the right refrigerant for you.

Should I choose a refrigerant based only on GWP with the AIM Act Phasedown?
The short answer is no. By choosing your refrigerant solely on GWP, you are leaving the AIM Act’s calculations out of the equation.

What are we missing if we only buy a refrigerant based on GWP?
Volume!  The AIM act specifies the quantity of allowances required to produce or import a unit of each HFC.  That quantity multiplied by volume gives you the total number of allowances needed. There are no allowances required by the EPA in the actual sale of the product once it has been produced or imported.

How does the EPA calculate refrigerant volume via the AIM Act ruling?
This value is determined by the equation:
 Volume (usually in Metric Tons) X GWP (AR4 value) = Metric Tons of CO2 equivalence 
The EPA uses the term MTEVe, but they mean the same thing. 

What is an example?

Let’s look at R-410A. The two likely HVAC replacements are R-32 and R-454B.  The GWP of R-32 is 675, and the GWP of R-454B is 466.  If that is all you knew it would be an easier choice, but due to the mass flow rates of each refrigerant, the charge size is significantly different. 

In the case of R-32, the charge size is reduced ~ 20%. A unit that would normally hold 5lbs of refrigerant would be roughly 4lbs of R-32.  By using the EPA calculation, the MTEVe value is 1.1 for R-454B, and 1.2 for R-32.  Both MTEVe’s are close enough that they will likely both be available for use roughly the same amount of time in the AIM act program.

It’s impossible to predict what new innovations or regulations will take place in the future. But it is possible to better understand how to compare the products available based on the AIM Act calculations. Refrigerants like Forane® R-32 can be lasting alternatives to legacy refrigerants and still have impacts as sustainable lower GWP refrigerants. By taking a look at the bigger picture, you will have more room to focus on things like cost and efficiency of the overall unit.

Thus, when considering what refrigerants will last the longest, make sure you consider volume as much as you consider GWP.