[Equest-users] Help-Exhaust-Makeup System

[Keith Swartz]

Loi,

I have also used the dummy zone approach for modeling emergency ventilation systems. Just have the emergency air flow go in and out of the dummy zone. It works best if the emergency ventilation system does not interact with how the main system operates, like if the ventilation system makeup air is brought into the room at room temperature. If the makeup air is unconditioned and the main system sees a heating or cooling load as a result, in the model you can condition the makeup air with the same heating and cooling efficiency as the main system to cover that energy use. In your case I would use the heating efficiency of the duct furnace and the cooling efficiency of the main DX cooling system to condition the makeup air going into the dummy zone. In the summer some of the makeup air may get exhausted before the cooling system gets a chance to cool it, so you may want to do something to adjust for that. (Don't cool all the way to room temperature?)

This dummy zone approach also works well with kitchen hood exhaust/makeup if you are not transferring air from other spaces.

________________________________
Keith Swartz, P.E., LEED AP

Energy Engineer / Senior Project Manager
Energy Center of Wisconsin
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From: Dahlstrom, Aaron [mailto:ADahlstrom at in-posse.com]
Sent: Thursday, January 05, 2012 1:53 PM
To: Loi Ng; equest-users at onebuilding.org
Subject: Re: [Equest-users] Help-Exhaust-Makeup System

Loi - I'd recommend a dummy zone.

No envelope loads, scheduled intake / exhaust scheduled based on when you think the CO sensor will trigger.

Aaron

Aaron Dahlstrom , PE, LEED(r) AP
In Posse - A subsidiary of AKF| 1500 Walnut Street, Suite 1414, Philadelphia, PA 19102
d: 215-282-6753| m: 267-507-5470| In Posse: 215-282-6800| AKF: 215-735-7290
e: ADahlstrom at in-posse.com | in posse web: www.in-posse.com<http://www.in-posse.com/> | akf web: www.akfgroup.com<http://www.akfgroup.com/>



From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Loi Ng
Sent: Thursday, January 05, 2012 2:21 PM
To: equest-users at onebuilding.org
Subject: [Equest-users] Help-Exhaust-Makeup System

Hi,
I am modeling a fire house.  I encountered a problem at the fire truck bay.  There is a DX cooling / furnace heating system at the fire truck bay for basic air-conditioning.  I am wondering if anyone know how to model a separate emergency exhaust/makeup system for the fire truck bay, which will not affect the sizing of the DX cooling / furnace heating system.  The emergency exhaust/makeup system is controlled by the CO sensor and has a duct furnace at the makeup air.

Thanks!

Loi Ng
Mechanical Engineer, LEED(r) AP
Diversified Engineering, Inc.
914 Silver Spring Avenue, Suite 208
Silver Spring, MD 20190
Tel: 301-565-2000 x 234
Fax 301-495-1563


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