[Equest-users] Increassed cooling consumption with DCV Modeling

[Daniel Knapp]

As I have noted before (http://lists.onebuilding.org/htdig.cgi/equest-users-onebuilding.org/2015-December/001790.html) in my experience, the best way to do DCV in eQUEST is to do a manual calculation of the expected reduction in OA rates by looking at the fan schedule and the occupancy schedule. Keep in mind that only the “people” part of the OA rate will be reduced, whereas the “area” part will stay the same.

If you’d like to know what your model is doing you may want try comparing the hourly outdoor air rates for your system with and without DCV. You can create an hourly report for the system in question with the hourly supply flow rate and outdoor air fraction printed to the hourly report file.

I know that the new version of DOE2.3 has made some changes to the outdoor air calculation methodology but I haven’t had a chance to test this yet.

All the best,

Daniel

From: Equest-users <equest-users-bounces at lists.onebuilding.org> on behalf of Harshal Gupta via Equest-users <equest-users at lists.onebuilding.org>
Reply-To: Harshal Gupta <harshal8899 at gmail.com>
Date: Friday, January 11, 2019 at 10:24 PM
To: "equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org>
Subject: [Equest-users] Increassed cooling consumption with DCV Modeling

Hello Energy Modelers,

This is regarding to increased cooling consumption while modelling DCV in eQUEST.I have prepared a hourly analysis on a single zone modeled without and with DCV, hourly result is attached.

Modeling Inputs

  1.  Project Location : Bangalore India (moderate climate).
  2.  Occupancy profile : 90% in office hours and 50% in lunch hours
  3.  Minimum air schedule is modeled in air side and minimum control is set to DCV reset down.
The outcomes are summarize below:

                                                         =Without DCV-With DCV

Remarks

                Difference in supply air flow (btu)

2,98,886

Reduced

Difference in latent (btu)

0

No change

Difference in total tonnage (TR)

-1,764

Increased

Difference in fresh air (CFM)

8,51,210

Reduced

Difference in vent fan consumption (kW)

32

Reduced


Queries :

  1.  Supply flow air and vent fan consumption is reduced, why their is an increment total cooling consumption.
  2.  Why their is no change in Total SPACE latent heat load from LOADS (Btu/hr).
  3.  What should be the correct way to model this and get efficiency.



Warm Regards
Harshal Gupta
Energy Analyst
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