Hi all,
Modelling DCV has been discussed many times in this forum. I gone through and understand quite a bit. I am listing my understanding along with some quires. Any response is much appreciated.
Our project is in Zone1A and is a metro transport building. project design considers Co2 sensors for DCV in zone level and system level in densely occupied area to meet the requirement of ASHRAE and LEED IEQC1 i.e. where the density is more than 25 people per 1000 sqft. Project also employs DOAS with Heat recovery to supply fresh air all the equipment inside the building i.e. AHU, FCU, CRAC.
I modelled same outdoor air quantity for base and proposed case.
My confusion is listed below and appreciate any clarification on this:
1. As some of the space meets the section 6.4.3.9, do I need to model DCV in Baseline?
2. I hope, the answer would be “yes” for my first question. In such case, how to model it in baseline. Let’s say there are 100 zones in a floor and 3 zones in that floor are highly occupied area (DCV required). There will be one system for the whole floor as per G3.1.1, which says, for systems 5,6,7and 8, each floor shall be modelled with a separate HVAC system. We can model DCV schedule in system level which will apply to all the zones served by the system. In this case, apart from these three zones, other 97 zones will have considered to have demand control ventilation. How to address this issue? FYI, I am using Equest software.
3. To address the above issue, can I provided separate system (System 3 or 4) for these zones only to model DCV as the Minimum OA schedule varies significantly w.r.t other zones served by this same system in baseline?
4. If the answer is no for my first question can I just model DCV in Proposed case and take credit? (hopefully the answer will be no).
5. The zones with high dense occupancy required to have DCV in base line has DCV control designed in the proposed case. Since DCV is required to be there in both base and proposed can I not model DCV in both the cases?
Request prompt response and appreciate any response.
Regards
VEL
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
June 2, 2017 - 9:08 am
1. Yes
2. I think you can enable DCV at the system level and then enter a specific constant cfm at the zone level for those zones without DCV and a cfm/person for zones with DCV. This would then map to the occupancy schedule for that space.
3. If you can't do the above then you should create a separate system with the same parameters (efficiency, etc.) as the system for that floor. You should explain what you have done in a narrative to the reviewer.
4. It is no.
5. You do model DCV in both cases and the quantity of outside air should be identical in these spaces.