[Equest-users] Appendix G Fan Simulation

[Gregg Liddick]

Although this may be obvious I would like to add that the temperature set points should be the same in both design cases per Table G3.1.1b.


Best Regards,

Gregg Liddick, EIT, LEED(r) AP

The Epsten Group, Inc.
429 Edgewood Avenue
Atlanta GA 30312
Phone: 404-577-0370  ext. 102
Fax: 404-577-1739
www.theepstengroup.com<http://www.theepstengroup.com>

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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of ron lamarre
Sent: Saturday, September 19, 2009 12:49 AM
To: Matthew Higgins
Cc: Equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Appendix G Fan Simulation

Hi to all:

I believe that the kW/CFM is based on the Baseline BHP and Baseline Fan Power formula in ASHRAE 90.1-2004 G3.2.1.9.  The CFM is the total building CFM; see the air-side summary report for the total bulding CFM.

To get the correct total building CFM, set the Baseline supply-air-to-room-air at a 20-degree F differential.  For instance, if your summer (cooling) set-point temp = 75 degreesF, then the cooling supply air temp from the unit is 55-degree F.  If your winter (heating) set-point temp is 70-degree F, then your heating supply air temp from the unit is 90-degree F.  Run a simulation and eQUEST will determine the CFM for each system based on this differential; then balance the systems to be under the 300 unmet hours limit.  Then open the air-side summary report to see the total CFM of all your systems.  Use that total CFM in the BHP and Baseline Fan Power calculations under G3.2.1.9.  To use the formulas, you need to use a calculator with a "natural log" button and an "e" button for the energy constant (e=1.28....just like "pie" = 3.14).
For a Baseline Type 3 PSZ System, the fan power should be in the neighborhood of 0.0007; this may be why GBCI questioned your result.  Then assign this fan power to each baseline PSZ system in your building and re-run the simulation.  Include the formula in the LEED submittal template or narrative to demonstrate how its calculated; as well as including the Air-side Summary Report.  GBCI will see both the total baseline CFM and the baseline fan power calculations.

The Proposed conditions are the proposed set-points, proposed supply air temps, and proposed kW/CFM for each system as designed.  If the RTU fans run continuously during occupancy periods, separate the supply air fan power, which is the kW to use, from the RTU power.  This allows design teams to take credit for using high efficient HVAC systems (low kW/CFM).

Hope this helps.

Ron Lamarre, AIA, NCARB
Architect - LEED AP



________________________________
From: Matthew Higgins <higgins at edi-arch.com>
To: "Equest-users at lists.onebuilding.org" <Equest-users at lists.onebuilding.org>; BLDG SIM <bldg-sim at gard.com>
Sent: Thursday, September 17, 2009 5:12:10 PM
Subject: [Equest-users] Appendix G Fan Simulation

I've seen multiple posts regarding 2004 Appendix G Fan Power and one post from Ming Zeng suggested the following:
"Baseline model fan usually gives 0.00078KW/cfm.  For proposed fans, typically it is 0.00016-0.00018 KW/cfm/in static*"*

I have two problems related to this because my Baseline KW/cfm is closer to 0.001 KW/cfm for a bunch of unitary Type-3 systems, which is indefinitely way too high.

FIRST
Many people have referred to the calculated fan power as an allowance, which to me, would appear to be a threshold not to exceed based on the 20deg-F delta for Appendix G Fan Sizing. I figure this is not the case because others refer to the fan power as something that is simulated in the model as a KW/cfm.
I've also seen posts where numbers are expressed as KW/kcfm, which would indicate fan power KW per thousand cfm; which again is not an applicable figure for simulation using eQuest.

SECOND
I'm struggling with these items because a recent GBCI reviewer has asked me to re-calculate my fan power because my BHPs are a bit higher than they should be. When I "re-calculate" these values I do not come up with the numbers they do (BHP ASHRAE - attached).

I'm trying to reconcile my response and eQuest inputs before we re-submit, but I'm not sure what to do.

Much thanks.

-- Matthew Higgins, LEED AP + ASHRAE-HBDP
Environmental Dynamics, Inc.
Architecture and Sustainability Consulting Services
505.242.2851 x.103

Any data provided by the Consultant, verbal or written, are to be considered opinions of building energy and/or daylight performance. The Client understands that the Consultant has no control of occupant habits, equipment or material performance or characteristics, site or climate conditions or the Contractor's method of assembly, and that the Consultant's opinions regarding building energy/daylight performance are made on the basis of the Consultant's professional judgment and experience. The Consultant makes no warranty, express or implied, that the energy/daylight performance of the building will not vary from the Consultant's opinion of building energy/daylight performance.

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