Hi! We use a heatpump system, which is used to supply heat as back-up solution. The processes in our building produce waste heat which is utilized for heating the building, but in case extra heating is needed the heat pumps kicks in.
The heatpump uses R407C.
How to determine the cooling capacity then? The system is not made for cooling at all, it has 24 kW of heating capacity.
I would think that the form does not support this kind for system.
Can I ignore the heatpump for this credit?
Many thanks in advance.
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Melissa Kelly
Sustainability SpecialistGensler
85 thumbs up
February 18, 2015 - 6:34 pm
Hi Juliane,
This is a really interesting question! Although there's no clear international compliance path for this credit that I know of that could provide clear guidance, it'd be great to hear if anyone's had experience with this on international projects in heating-only climates.
When it comes down to it, the intent of this credit is all about the use efficiency of the refrigerants for space conditioning compared to their environmental impacts. My instinct is that it makes sense to use the heating capacity instead of the cooling capacity in the calculations, because then you're still finding the average refrigerant impact per kW of conditioning capacity. If you do go this route, I would be sure to provide at least an extra narrative explaining that the calculations are based on heating capacity to avoid confusion.
Lyle Axelarris
Building Enclosure ConsultantBPL Enclosure
64 thumbs up
February 20, 2015 - 1:19 pm
Yes, definitely an interesting question. Please keep us updated if you decide to include heat capacity in your calcs. I agree with Melissa that including heating capacity in calcs is in alignment with the intent of the credit. Taking this one step further then, do you think that both cooling AND heating capacity should be included in calcs for a VRF system that transfers excess heat from one part of the building to another part? If instead of VRF, the spaces were cooled and heated with two separate systems (and the heating system was a heat pump), then following the logic of this thread, you would account for refrigerant in both the heating and the cooling systems. So wouldn't it be appropriate then to account for both heating and cooling capacities in a single VRF system?
Melissa Kelly
Sustainability SpecialistGensler
85 thumbs up
April 17, 2015 - 11:11 am
Hi Lyle,
It sounds like what you're talking about is a heat recovery function in the VRF system. From a holistic perspective, that would be a great strategy compared to the alternative you suggest as far as reducing both refrigerant and potentially energy as well. However, if the excess heat is already in the building and not brought in from the outside through a refrigerant cycle, it seems to me like it starts to go beyond the simple equipment refrigerant use efficiency metric that this credit is based on.
There are also some other special considerations for VRF and VRV systems for this credit which are covered in the Bird's Eye View above.