Hi Joe,

Thanks for your question regarding LEED-NC EA Credit 4: Enhanced Refrigerant Management.

The environmental room you describe sounds very interesting. I have to assume that this room is part of a larger building that is attempting LEED certification, as it doesn’t seem possible that a single room would be able to earn enough credits for LEED certification.

If this is true, then I would also assume that this larger building would have other types of HVAC equipment in it. According to the LEED-NC 2009 Reference Guide, “for multiple types of equipment, a weighted average of all base building HVAC&R equipment must be calculated using the following formula:”

∑ ( LCGWP + LCODP x 105) x Q unit

—————————————————

Q total ≤ 100

What that means is, even though this one particular piece of equipment may have a large number of refrigerant charge per ton, the other pieces of mechanical equipment in the building may make up for it using this calculation and the credit may be still be earned. Each piece of equipment in a building does not have to be less than 100 using the calculation in the reference guide. It’s the weighted average of all building HVAC equipment that counts.

Now, if this is indeed the only piece of HVAC equipment, then you may have a problem because as you said, 10 pounds of refrigerant per ton of gross ARI cooling capacity will adversely affect the calculation. In order to mitigate this, you would have to choose another refrigerant that would bring down the Global Warming Potential (LCGWP) number in the calculation. The type of refrigerant used will determine this number. I suggest using a natural refrigerant, such as ammonia, water or carbon dioxide, as recommended in the LEED-NC 2009 Reference Guide. The global warming potential (GWP) for those refrigerants is negligible. If that is not possible, the most common refrigerant with a somewhat low GWP is R-123.

Good luck!

Dave

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