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NC-v4 EAp2:Minimum energy performance

Various FCU's in Single Zone

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Green Lab
LEEDuser Basic Member
6 thumbs up

Hello Everyone,

I am currently modelling an office Building with DOAS + non ducted FCU 4 pipe system (90.1 - 2010), in Design Builder (Energy Plus). Some zones have a single FCU, others have various FCU's of the same type, and other zones have a combination of FCU placed on ceiling and on the floor with different technical characteristics, but all have 3 speeds (low medium and high) and similar temperature and water flow regimes.

My question is, for each zone even if the FCU characteristics are different (specific fan powers, etc.) do you usually group all FCU into a equivalent one, or in this case would you model various FCU systems in a single zone.

In other words, may I sum all FCU coil capacities, airflows, fan powers, etc. and model all FCU's using a single equivalent FCU object for each Zone Group?

I hope my question was clear and thank you all in advance.

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Waleed AlGhamdi
Sustainability Enabler
Eskew+Dumez+Ripple
LEEDuser Basic Member
20 thumbs up

Tue, 06/25/2019 - 14:37

If there is only one thermostat controlling all FCUs, I've always grouped them into one system with the system parameters summed up. I've never heard any issues with this approach. There is an issue if a single zone is served by more than one system *type*, and in your case, the same zone will be served by and FCU and a DOAS. I heard that Energy Plus can model this natively, but I'm not sure. In my experience with eQuest, we resort to a workaround to model this scenario. 
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Green Lab
LEEDuser Basic Member
6 thumbs up

Tue, 06/25/2019 - 15:13

Yes, there is only one thermostat controlling all FCUs. I will group them all into one system then. Thank you Waleed.

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