[Bldg-sim] [Trace-users] Baseline Fan Power with DOAS in proposed and not in baseline

[Nick Caton]

Hi Nick,

For hand calcs and to avoid doubled-work, note the LEED EAp2 spreadsheet version updated in the end of 2012 already requires the inputs to arrive at your required baseline fan power, inclusive of the static "credits" which bump up baseline fan power to be on a more level playing field with your proposed systems.  If that spreadsheet is in play and you're still learning the procedure for hand calcs, It would probably be time-efficient to start there and to transpose/re-create those results as you may need to for other calculations.

G.1.2.9 outlines the entire baseline fan power calculation procedure, and the referenced sections and subtext will have you bouncing between here and chapters 6/10 to pull pressure drop adjustments and motor efficiencies.

Keep the system #7 specific passages at the last pages of Appendix G in mind - Your baseline and proposed models feature fundamentally different fan arrangements, so you want to ensure your proposed model is taking full advantage of the relative benefits of terminal fan powered boxes relative to a system with a central fan only.

I'm not personally intimate with what Trace automates these days, but applaud your efforts to understand what's going on "under the hood."  It's a sign of a quality energy modeler, and will assuredly lead you to better results and open doors for your energy analysis tool belt.

~Another Nick

[cid:489575314 at 22072009-0ABB]

NICK CATON, P.E.
SENIOR ENGINEER

Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Anne C. Juran
Sent: Thursday, July 25, 2013 7:58 AM
To: 'Nick Anderson'; bldg-sim at lists.onebuilding.org; trace-users at lists.onebuilding.org
Subject: Re: [Bldg-sim] [Trace-users] Baseline Fan Power with DOAS in proposed and not in baseline

The baseline fan power is per 90.1-2007 G3.1.2.9. It is independent of the proposed static pressure, other than the fan power adjustment factor, PD, which makes allowances for certain additional devices you might have in the proposed system. PD is used to solve for A... see 6.5.3.1.1. Trace will do the calc for you once you put in the proper fan and the fan power adjustment factor, PD.


From: trace-users-bounces at lists.onebuilding.org<mailto:trace-users-bounces at lists.onebuilding.org> [mailto:trace-users-bounces at lists.onebuilding.org] On Behalf Of Nick Anderson
Sent: Thursday, July 25, 2013 8:25 AM
To: bldg-sim at lists.onebuilding.org<mailto:bldg-sim at lists.onebuilding.org>; trace-users at lists.onebuilding.org<mailto:trace-users at lists.onebuilding.org>
Subject: [Trace-users] Baseline Fan Power with DOAS in proposed and not in baseline

I'm doing a LEED School simulation.  The proposed building has many water source heat pumps with a small fan in each that has 3/4" static pressure (typical 1000 CFM for example) and a dedicated outdoor air unit supplying a typical 200 CFM to a single WSHP zone direct to the space with its own supply and return fans with relatively large static pressures (4" Supply, 2" Return sp).  The baseline building system is 7, VAV with reheat.  The DOAS system is not necessary in the baseline system since it is an RTU.

When it comes to fan power in the baseline case, I am not sure how to keep the fans the same with such different arrangements and static pressures.  How do I apply the VAV with supply and return fans to represent the proper static pressure situation of the proposed building so that the fan power comparison is proper?  How do I calculate the baseline power for each unit?  I want to understand for hand calculations.

I am using the latest version of Trace and will be cross posting to the Trace list for program specific information on how to have Trace properly handle the calculations automatically.

Thanks for any help,
Nick

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