Modeling Residential Baseline (PTAC) with CHW + Humidity Control

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I'm modeling a project in the lower Louisiana area, very hot and humid, and where the baseline is PTAC, but cooling is supplied via a district plant (CHW). The relevant code is AHRAE 90.1 2007, and I'm trying to model the baseline with CHW instead of the DX cooling since it will be used in the proposed case. I've used FCU as the baseline system type, but in eQuest there's no humidity control with FCU, and it's the single biggest load in lower Louisiana. Has anyone done this in the past? How did you resolve it?

One way I've been testing to account for humidity controls is to model a dummy zone with a single zone reheat system (SZRH) with zero fan power and zero loads, but with heating and cooling schedules on the zone level. I've zeroed out the OA from zones and modeled all OA on the dummy zone, and set it's RH to 60%. CHW usage increased significantly for latent cooling (28%) and steam increased for reheat (54%). There was also a slight increase in pump usage.

Overall, this is the behavior I'd expect. For context, modeling the same setup for a FCU with a package DOAS and changing the RH from 100% to 60% increases cooling by 29% and heating by 36%. 

I'm open to any ideas!



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