[Equest-users] Fan energy fundamentals - Appendix G models

[R B]

Was looking at it the other day - not sure if this is what you are
referring to. The file is EDR_VAV_Guide_5-2-07 (too big to attach). see
page 210 onwards.

On Fri, Feb 24, 2012 at 10:05 AM, Bishop, Bill <bbishop at pathfinder-ea.com>wrote:

>  Would anyone like to share an input file (or paste the text into an
> email) with all the fan curves described in the EDR resource below? (Advanced
> Variable Air Volume VAV System Design Guide<http://www.energydesignresources.com/media/2651/EDR_DesignGuidelines_VAV.pdf>)
> The guide references a “New DOE-2 Fan Curves.txt” text file but I have no
> idea where/if I can download it. Yes, I probably could have typed it out
> myself by now but this gives me an excuse to post.****
>
> I offer the following curve-fit for Appendix G., Table G3.1.3.15 for any
> of you that don’t already have it for your LEED Baseline models. (Just copy
> and paste into the “Performance Curves” section of the input file.):****
>
> ** **
>
> "App G VAV Fan FPLR" = CURVE-FIT       ****
>
>    TYPE             = CUBIC****
>
>    INPUT-TYPE       = COEFFICIENTS****
>
>    COEFFICIENTS     = ( 0.0013, 0.147, 0.9506, -0.0998 )****
>
>    ..****
>
> ** **
>
> Thanks,****
>
> Bill****
>
> ** **
>
> ** <wbishop at pathfinder-ea.com>****
>
> ** **
>
> ** **
>
> *From:* Nick Caton [mailto:ncaton at smithboucher.com]
> *Sent:* Tuesday, October 11, 2011 3:45 PM
> *To:* Paul Riemer; Bishop, Bill; Dahlstrom, Aaron;
> Equest-users at lists.onebuilding.org
>
> *Subject:* RE: [Equest-users] Fan energy fundamentals - Appendix G models*
> ***
>
>  ** **
>
> I’ve also been surprised at the magnitudes involved, but these kinds of
> savings do seem very real.  One fundamental I had to wrap my head around
> (confirmed with some controls servicing contacts) is that large supply fans
> with VSD’s should rarely operate at or near full capacity when a system is
> being controlled correctly.****
>
> ** **
>
> Small differences as the curves approach zero really add up over 8760
> hours however.  The EDR resource linked below is really a better teacher
> than myself, but if you’ll compare the curves I posted below, you’ll notice
> they’re actually very different at most PLR’s.  Actually I can overlay
> these pretty quickly with my personal curve spreadsheet:****
>
> ** **
>
> ****
>
> ** **
>
> When looking at these: consider the same system operating at any given
> PLR:  The difference may seem small, but at 20% PLR the system with the
> library curve is drawing double the energy of the 90.1 curve.  Similar
> story but inversed around the 40% mark.  Bill’s model producing a ~50%
> difference in fan energy consumption between the curves is not outside the
> realm of reason considering this –his hourly PLR distribution through the
> year and minimum flow ratios would factor in, of course.****
>
> ** **
>
> I more strongly do not believe these two particular curves are
> apples-to-apples however.  My present understanding is the library VSD
> curve (the “Nike swoosh”) represents a VSD fan system without static
> pressure reset (as prescribed by 90.1).  The other curve shape (umm…
> “upturned banana?”) does look like fan system curves incorporating a static
> reset sequence, but it’s still weird that it actually approaches zero at
> zero (well technically 0.0013)… .****
>
> ** **
>
> This is something I haven’t reconciled with reality just yet… One thought
> is it would appear to represent a perfectly efficient duct system with zero
> static pressure to overcome at low flows – perhaps that means for a level
> playing field we’re supposed to assume the same for a proposed curve?  Is
> there language in 90.1/users’ manual that explicitly says something along
> the lines of “duct/pipe distribution losses are not supposed to be modeled?”
> ****
>
> ** **
>
> Still mulling this over… =)****
>
> ** **
>
> ~Nick****
>
> ** **
>
> [image: 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:* Paul Riemer [mailto:Paul.Riemer at dunhameng.com]
> *Sent:* Tuesday, October 11, 2011 2:06 PM
> *To:* 'Bishop, Bill'; Nick Caton; Dahlstrom, Aaron;
> Equest-users at lists.onebuilding.org
> *Subject:* RE: [Equest-users] Fan energy fundamentals - Appendix G models*
> ***
>
> ** **
>
> I agree it is not trivial but I am really surprised by that 50.8% number.
> I think the curves are relatively similar at the high end and most systems
> rarely spend time on the low end where the curves do differ considerably.
> Is there a big difference in the system volumes, specifically are the
> baseline fans bigger in volume and thus always operating at a lower ratio
> than the proposed?****
>
> ** **
>
> Generally, I assume that the curve in 90.1 was supposed to represent a VAV
> VFD curve and that my VAV VFD fans should not be penalized against it.  VAV
> vs. CAV is trickier and brings the temptation to switch your rationale
> based on which side your project falls on. ****
>
> ** **
>
> *Paul Riemer, PE, LEED AP BD+C* ****
>
> *DUNHAM*****
>
> ** **
>
> *From:* Bishop, Bill [mailto:wbishop at pathfinder-ea.com]
> *Sent:* Tuesday, October 11, 2011 1:07 PM
> *To:* Nick Caton; Paul Riemer; Dahlstrom, Aaron;
> Equest-users at lists.onebuilding.org
> *Subject:* RE: [Equest-users] Fan energy fundamentals - Appendix G models*
> ***
>
> ** **
>
> Nick’s concern about VAV fan curves is not trivial. I am working on a LEED
> model using Baseline System 5 (PVAV). The Baseline fan energy using the
> 90.1 G3.1.3.15 VAV FPLR curve is *50.8%* more than the fan energy using
> the default eQUEST “Variable Speed Drive FPLR” curve. YMMV of course but
> that is a big difference. This penalizes the Baseline for my project – the
> total electrical use increases 8.9% in the Baseline vs. only a 4.1%
> increase in the Proposed model when switching to the same G3.1.3.15 curve.
> ****
>
> ** **
>
> Bill****
>
> ** **
>
> [image: Senior Energy Engineer]****
>
> ** **
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Nick Caton
> *Sent:* Tuesday, October 04, 2011 3:30 PM
> *To:* Paul Riemer; Dahlstrom, Aaron; Equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Fan energy fundamentals****
>
> ** **
>
> Paul & others:****
>
> ** **
>
> I just wanted to say off the bat:  the EDR resource Paul linked us looks
> to address the heart of my query directly (and thank you so much!), but
> it’s difficult for me to summarize further right now…****
>
>
> I think I’ll need to re-read the appropriate parts of this document a few
> times over and arrive at a deeper understanding of actual
> methods/sequencing strategies for static pressure reset before I come to
> any definite conclusions regarding VAV fan curve.  ****
>
> ** **
>
> The query I’m trying to nail down is what assumptions and specific system
> behaviors the DOE2 library/default curves and particularly the prescribed
> 90.1-2007 baseline curve represent, and from there answer what’s fair game
> insofar as defining/modifying a different sort of EIR-FPLR curve for a
> proposed model.  I have the understanding that the associated fan energy
> savings between various approaches are potentially big and real, but I’m
> scratching the surface of how to actually model it to a realistic degree.*
> ***
>
> ** **
>
> If anyone has pondered the same topic or is a few strides ahead of me and
> wishes to share any thoughts/guidance, please do not hesitate =).****
>
> ** **
>
> ~Nick****
>
> ** **
>
> [image: 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:* Paul Riemer [mailto:Paul.Riemer at dunhameng.com]
> *Sent:* Friday, September 30, 2011 7:21 AM
> *To:* 'Dahlstrom, Aaron'; Nick Caton; Equest-users at lists.onebuilding.org
> *Subject:* RE: [Equest-users] Fan energy fundamentals****
>
> ** **
>
> As for fans I suggest two resources:****
>
> Advanced Variable Air Volume VAV System Design Guide<http://www.energydesignresources.com/media/2651/EDR_DesignGuidelines_VAV.pdf>by Energy Design Resources has some good discussion and suggested fan
> curves.****
>
> ** **
>
> Reid Hart of PECI did a presentation to BSUG on September 16, 2009 on fan
> curves and static pressure reset.    BSUG posted their items, including
> this one, to their yahoo group at
> http://tech.groups.yahoo.com/group/BSUG/files/. BSUG has morphed into
> BESF and has a new home at
> http://energytrust.org/business/building-energy-simulation/.****
>
> ** **
>
> *Paul Riemer, PE, LEED AP BD+C* ****
>
> *DUNHAM*****
>
> ** **
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Dahlstrom,
> Aaron
> *Sent:* Friday, September 30, 2011 12:03 AM
> *To:* Nick Caton; Equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Fan energy fundamentals****
>
> ** **
>
> Nick – ****
>
> ** **
>
> We’re in the midst of asking the same questions about the Pump-Power-fFlow
> equations.****
>
> ** **
>
> I imagine in both types of flow networks there may some fixed pressure
> drops that won’t be reduced:****
>
> 1)      Min static pressure across flow control devices (VAV boxes, water
> control valves)****
>
> 2)      Static pressure in critical branches that may not be at reduced
> flow, even though the overall flow network is at reduced flow****
>
> 3)      In staged plants, static pressure across individual
> constant-volume plant components (eg in our case, chiller 1 of 6 always has
> 12 psig, regardless of whether it is the only chiller on or not)****
>
> ** **
>
> With this mixture of fixed and variable pressure drops, I imagine multiple
> different power-versus-flow curves for the same building, depending on the
> physical location of the prime movers and the intervening pinch points /
> critical flow networks. 20000 cfm out of a peak 30000 cfm fan probably
> looks different in terms of power depending whether the majority is headed
> to west zones from an east mechanical room 400 ft away or headed to east
> zones just a few feet away.****
>
> ** **
>
> Probably the most accurate method would be explicitly defining the flow
> network and calculating these pressure drops dynamically (if the modeler
> had the time to do that explicitly, or software cool enough (BIM?) to do it
> automatically). Anyone familiar enough with Energy Plus to know if that’s a
> feature?****
>
> ** **
>
> I guess no answers here, just more questions …****
>
> ** **
>
> *Aaron Dahlstrom , PE, LEED® 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 | akf web:
> www.akfgroup.com****
>
>  ****
>
>  ****
>
>  ****
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Nick Caton
> *Sent:* Thursday, September 29, 2011 12:08 PM
> *To:* Equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Fan energy fundamentals****
>
> ** **
>
> Bill Bishop suggested a good clarification that I want to take on.  I’ve
> edited my language below (highlighted) to clarify the question I’m trying
> to pose.  ****
>
> ** **
>
> ~Nick****
>
> ** **
>
> *From:* equest-users-bounces at lists.onebuilding.org
> [mailto:equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Nick
> Caton
> *Sent:* Thursday, September 29, 2011 10:32 AM
> *To:* Equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] Fan energy fundamentals****
>
> ** **
>
> Hi everyone!****
>
> ** **
>
> A recent discussion with a mechanical mentor brought up a question I’d
> like to share with the list…  If anyone has a partial or complete response
> I think we’d all benefit and appreciate it if you’d share your thoughts!**
> **
>
> ** **
>
> For a given duct distribution system, you’ve got a certain static drop.
> At full flow, your supply fan also has to deal with a certain velocity
> pressure drop due to friction with the duct distribution.  If you reduce
> the supply airflow rate, you also lower the velocity and therefore the
> velocity pressure drops for the given duct distribution.  The net result is
> system supply fan has a lower total pressure drop to overcome, and so
> should operate more efficiently.****
>
> ** **
>
> Does anyone know:  Whether we choose “variable speed” fan control, use the
> FAN-EIR-FPLR curve generated by the wizards, or use the VSD curve defined
> in 90.1 appendix G… are we simultaneously accounting for the efficiency
> gains due to lowered velocity pressure drop in addition to the drop in fan
> energy from lower RPMs?  If this is not accounted for inside/outside the
> fan curves, is there a direct way to define that or logically work it into
> the curves?****
>
> ** **
>
> If it helps anyone answer, I can illustrate from recent checks that the
> wizard-generated FAN-EIR-FPLR curve has a “Nike Swoosh” shape with an
> inflection around the 20% mark.  This shape best matches the (limited) data
> I’ve seen for “real world” VSD input measurements.  Here’s a screenshot:**
> **
>
> ** **
>
> ****
>
> ** **
>
> The following illustrates the 90.1-2007 VAV curve we’re made to use for
> baseline systems 5-8 (I haven’t checked to see if this still applies to
> 2010).  It does not have the same “inflection point” as zero is
> approached.  I think it’s based on the fan law power equation or something
> similar that doesn’t account for motor/VSD losses:****
>
> ** **
>
> ****
>
> ** **
>
> The help files illustrate a different, third shape for “variable speed”
> control different from both of the above…****
>
> ** **
>
> ****
>
> ** **
>
> Seeing these side-by-side raises another question for me regarding
> 90.1-2007 intent/practice… not specific to eQuest… but I’ve already spent
> too much of my time today writing this out!  Another day =)…****
>
> ** **
>
> Thanks in advance for anyone joining in the discussion!****
>
> ** **
>
> ~Nick****
>
> ** **
>
> [image: 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* *****
>
> ** **
>
>
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