Has anyone had any experience combining the approaches in Option 1 and Option 2 to achieve this credit? We plan to use economizer cooling for most of our cooling needs. Economizer cooling is simply increasing outdoor air flow rates when cooling is needed - in our climate, OA is cooler than indoor spaces subject to internal loads. We do also have a few small split-AC units for communication/server rooms, so we cannot use Option 1. However, we are minimizing the amount of refrigerant used in the building by cooling with outdoor air (which has ODP=0 and GWP=0). It seems reasonable to me to claim credit for the refrigerant reduction inherent in economizer cooling.
My approach to documentation is this: Use Option #2, but instead of using the Rc of the AC units and refrigerant lines, I plan to modify the Rc to take into account the cooling provided by economizer cooling. The modified Rc would be equal to the total refrigerant charge of the AC system divided by the total cooling tons provided to the building by BOTH the AC system and the Economizer system. This would result in an accurate "unit of refrigerant per unit of cooling" figure.
A different method that just occurred to me would be to add the economizer cooling system as a separate HVAC equipment, with "Refrigerant Used" being "None" (in EAp3 template). This seems more direct to me.
Has anyone used this approach before? Do you think this is reasonable?
Thanks for your input.
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David Rekker
Project PrincipalMMM Group Ltd.
5 thumbs up
June 20, 2014 - 9:45 am
Unfortunately, the credit does not incentivize reduction in refrigerant (unless no refrigerants are used at all). Rather, it is based on refrigerant management which takes into account leakage rates, equipment life, and types of refrigerant used. So, regardless of how often you are using your refrigeration equipment, you need to enter the data from all systems.
As you can imagine, your economizer strategy is used very often here in Canada. However, it is rare that an owner will agree to zero DX cooling. It seems you might be in the same boat, since you say that economizer mode will be used for "most" of you cooling.
Lyle Axelarris
Building Enclosure ConsultantBPL Enclosure
64 thumbs up
June 20, 2014 - 9:48 pm
Thank you, David. It still seems to me that using a cooling system that has no refrigerants (i.e. Economizer cooling) reduces the ozone and global warming impact related to cooling the building. 92% of the cooling load for the building is handled by a zero-refrigerant system. Over 95% of the floor space of the building is conditioned by a zero-refrigerant system. Isn't this better than using refrigerant-based cooling systems to condition the whole building (meaning more refrigerant leaking, more emissions, etc.)? I don't understand the logic of treating the zero-refrigerant approach as an all-or-nothing proposition.
David Rekker
Project PrincipalMMM Group Ltd.
5 thumbs up
June 23, 2014 - 9:24 am
Hi Lyle. I'm with you, I just don't know of a USGBC ruling to support this method (e.g. you may need to make an official query). I searched the CIRs here in Canada, and there is a recent one (February) where the applicant is using evaporative cooling (no refrigerants) for most of the building, and then split systems for servers etc. They wanted to know if/how they could account for the evaporative system. It seems the CaGBC's answer leans your way (I should have checked these first!):
"Projects using evaporative cooling may consider these systems in the EAc4 calculations under Option 2. For simplicity, in order to calculate the Average Refrigerant Atmospheric Impact, the ODP and GWP of the evaporative cooling system can be entered as zero in the LEED Letter Template for this system. Furthermore, any number may be entered under the Rc (lb/ton) for this system as this value become irrelevant to the calculation when ODP and GWP are zero. ... Submissions should include a narrative explaining the conditions at which the rated capacity (Qunit) of the evaporative cooling system is determined."
You may want to use this as a basis for your question. Canadian CIRs are not applicable to the USGBC, but should provide an indication.
Lyle Axelarris
Building Enclosure ConsultantBPL Enclosure
64 thumbs up
June 23, 2014 - 2:29 pm
Thank you, David. That is very helpful. Can you please tell me what CIR# (or LI-Canada#?) you are referring to? I'm not sure if I have access to Canadian CIR database, but it will help me to find it or reference it accurately.
David Rekker
Project PrincipalMMM Group Ltd.
5 thumbs up
July 3, 2014 - 10:37 am
Sorry for the delay, Lyle. I am referring to CIR 1105: "Using evaporative cooling systems under EAc4 Option 2". Hope that helps.
Laura Charlier
LEED Services DirectorGroup14 Engineering, Inc.
58 thumbs up
August 28, 2015 - 1:47 pm
Hi there-
Just curious if anyone has pursued this methodology (and earned compliance) for EAc4 with evap cooling to date?
Thanks!
Lyle Axelarris
Building Enclosure ConsultantBPL Enclosure
64 thumbs up
August 28, 2015 - 9:50 pm
It worked for me for economizer cooling. I think the key was a very proactive narrative justifying the approach. I think this should be incorporated into an addenda.