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NC-v4 EAp2:Minimum energy performance

Baseline: existing heat pumps, new FCs

I'm modeling a commercial building that has 7 conditioned floors and is heated and cooled by 3 electric heat pumps. According to TABLE G3.1.1A the baseline model should be a System 8. Nevertheless, since 2 heat pumps are existing (before the works) they shall be modelled in the baseline system too (the 90.1-2010 User's Manual states: "In some cases, a complete HVAC system already exists (...) the proposed building and baseline building models are the same and are based on the existing HVAC system"). The fan-coils that are connected to the hot water loop and to the chilled water loop are being replaced.
How shall the HVAC system of the baseline model be? The two existing heat pumps connected the new fan-coils (e.g. the fan power of the new fan-coils)? No relationship with System 8?

Best Regards

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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Wed, 06/13/2018 - 16:46

I think that the User's Manual is pretty clear on this issue. The heat pumps should be modeled identically in both models. The new components should be modeled using the Appendix G requirements. However, GBCI has been somewhat flexible on this issue and you might be able to get away with using a System 8.

Fri, 06/15/2018 - 09:29

Thanks. "The new components should be modeled using the Appendix G requirements." The new components are fan-coils.
Shall fan-coils be modeled in the baseline model? If yes, it seems that there are no requirements in App. G for fan-coils (connected with water loops), are they? Best Regards  

Fri, 06/15/2018 - 09:40

I see a possible solution: I'll model System 8 but chilled water will be produced by the heat pumps and the electric coils will be replaced with hot water coil. The hot water will be produced by the heat pumps too. Would it be fine?
Profile picture for user sheffer
Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Fri, 06/15/2018 - 14:34

The baseline fans should follow the guidance in G3.1.2.9 and G3.1.2.10. What you propose makes sense assuming that the heat pumps produce both hot and chilled water.

Fri, 06/15/2018 - 16:12

Yes, the heat pumps produce both hot and chilled water. Thank you!

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