[Equest-users] Exhaust Ventilation Modeling

[Kathryn Kerns]

Everyone,   I have been trying to model a kitchen classroom building
with large kitchen hood exhaust air flows.  The building is small enough
so the baseline HVAC should be single zone constant volume and I assume
it should have constant volume make-up air for the constant volume
kitchen exhaust hoods. The proposed HVAC design for the building is
mostly VAV, the proposed kitchen hood make-up air system is VAV, and the
proposed exhaust kitchen hoods are constant volume.

 

Attached are snap shots showing an example AHU/zone for the baseline
energy model and snap shots showing an example zone and related AHU for
the proposed building model. Also attached are the over all simulation
outputs for the baseline and proposed energy models and the cooking
schedule that runs the baseline and proposed exhaust fans. (At least I
think it does)

 

When I changed the cooking schedule daytime hours fraction from 0.4 to
0.2 in both models, I noticed some odd results. The baseline energy
model's total heating, fan and cooling energy consumptions did not
change, remaining at 234.38 clg, 400.58 fans, 4,345.2 htg. The proposed
energy model total heating changed form 3224.4 to 2957.2, the cooling
changed from 291.12 to 221.62, and the fan energy changed from 303.69 to
303.43.

 

So my questions are: 1) why didn't the baseline energy levels change? Is
it because I selected constant volume and that ignores the cooking
schedule? I thought it said in the help item directions that it wouldn't
ignore the schedule. 2) why didn't the fan energy in the proposed model
change along with the heating and cooling energy? Seems to me it should
have.

 

Can anybody tell me what I am doing wrong or suggest a better way to
model large kitchen hood exhaust building?

 

 

Kathryn Kerns

Systems Specialist

BCE Engineers, Inc.

| Ph: 253.922.0446 | Fx: 253.922.0896 | 

 

 

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