[Equest-users] Equest-users Digest, Vol 61, Issue 7
anura perera
perera.anura25 at gmail.com
Sat May 10 01:40:24 PDT 2014
Dear All,
I am modeling a multi-story industrial building that has got mechanical
ventilation. But in view of the ASHRAE definition of "conditioned spaces"
this will not qualify as "conditioned". However Appendix G requires
modelling Cooling and heating systems even if they are not installed or
designed in the proposed case and both Baseline and proposed
cooling/heating systems have to got same characteristics.
Could someone throw light on the methodology and also indicate whether 300
unmet hours condition is to be still complied, which will not be easy as
both baseline and proposed have the same characteristics.
Thanks in advance
Anura
On Mon, Apr 8, 2013 at 1:32 AM,
<equest-users-request at lists.onebuilding.org>wrote:
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> 1. Re: CHW loop process load (fiona.you at cn.bureauveritas.com)
>
>
> ---------- Forwarded message ----------
> From: fiona.you at cn.bureauveritas.com
> To: James Hess <JHess at tmecorp.com>
> Cc: "equest-users at lists.onebuilding.org" <
> equest-users at lists.onebuilding.org>
> Date: Sun, 7 Apr 2013 13:26:03 +0800
> Subject: Re: [Equest-users] CHW loop process load
>
> Hi James,
>
> Thank you for your sharing. I am doing a district chilled water project at
> present, your information is very useful.
>
> I made the Baseline model with chillers and cooling towers as indicated in
> Apppendix G. The proposed model is modeled with one air-cooled chiller with
> average efficiency+piping loss.
>
> One thing I am not clear is what's the chiller curve like in your model?
> Because it is hard to set curves as a constant value. For example, a
> chiller's EIR curve should be a quadratic curve, how do you make it into a
> constant value?
> Best Regards!
>
>
>
>
>
> *游超 ** Fiona You*
> *高级**LEED**咨询师 ** Senior LEED Consultant* 必维国际检验集团 工业与设施事业部
> Bureau Veritas Industry & Facilities Division
> 中国上海市浦东新区陆家嘴软件园 8/F Building No.8 Pudong
> Lujiazui Software Park,
> 峨山路91弄120号8号楼8楼 邮编: 200127 No.120, Lane 91, E Shan
> Road, Shanghai 200127, P.R.C.
> Tel: +86 21 6886 0643 Ext.8557 Fax: +86 21
> 6886 1421 Mobile: +86 180 1750 1596
> Web : *www.bureauveritas.cn* <http://www.bureauveritas.cn/>* (CHN) | *
> *www.bureauveritas.com* <http://www.bureauveritas.com/>* (Global)*
> P *Save a tree. Don**’**t print this e-mail unless it is
> really necessary*
>
>
> [image: Inactive hide details for James Hess <JHess at tmecorp.com>]James
> Hess <JHess at tmecorp.com>
>
>
>
> *James Hess <JHess at tmecorp.com <JHess at tmecorp.com>>*
> Sent by: equest-users-bounces at lists.onebuilding.org
>
> 2013-04-06 03:36
>
>
> To
>
>
> Adam S <adam.scherba at gmail.com>
>
>
> cc
>
>
> "equest-users at lists.onebuilding.org" <
> equest-users at lists.onebuilding.org>
>
>
> Subject
>
>
> Re: [Equest-users] CHW loop process load
>
>
> Ref
>
>
> Those are good questions.
>
> Answer to 1st question = yes
>
> Answer to second is the following:
>
> To be practical about this and simplify the modeling, we create a constant
> efficiency air cooled chiller to simulate the default DESv2.0 plant.
>
> The EIR is entered equal to 0.839 kw/ton, which equates to 4.4 COP + 5%
> losses.
>
> This represents the energy usage of the plant chillers, plant pumps, and
> cooling tower.
>
> We further create and apply performance curves that keep the EIR the same
> versus load and temperatures. In other words, Avg EIR = Max EIR = Min EIR =
> the EIR we enter into eQuest.
>
> It's easier to do this with an air cooled chiller because then you don't
> have to worry about a cooling tower and tower water pump in the model.
>
> This approach is simple and it works. I've used it on several LEED
> projects involving district chilled water systems.
>
> We probably give up some savings with this approach, but it's a lot of
> work to correctly model the actual performance of an actual CHW system in
> accordance with DESv2.0. If this isn't in our modeling scope of work, we
> use the stipulated efficiency route.
>
> Hope this helps.
>
> P.S. The stipulated efficiency approach does not work out well when
> modeling heating water and steam systems because the default efficiency
> numbers for those systems are pretty bad. That's not the case with chilled
> water, at least if you are comparing to a Baseline based on air cooled
> equipment. If the building was big enough to require chilled water as a
> baseline, this approach will not work that well, and you would have to
> pivot to a new approach. Comparing the stipulated efficiency against a App
> G Baseline water cooled chiller plant would probably result in little to no
> savings in the cooling equipment category.
>
> Thanks!
>
> Regards,
>
> JAH
>
> On Apr 5, 2013, at 1:51 PM, "Adam S" <*adam.scherba at gmail.com*<adam.scherba at gmail.com>>
> wrote:
>
> Do you interpret the USGBC guidance for baseline district energy
> systems to be 4.4 COP + 5% losses averaged over the year? Meaning that the
> chiller in your model should be modeled with a better EIR so that the
> average annual COP calculated using the PS-C report is 4.4?
>
> Their use of the term "average efficiency" seems a bit vague.
>
> Thanks,
>
> -Adam
>
>
> On Fri, Mar 29, 2013 at 3:24 AM, James Hess <*JHess at tmecorp.com*<JHess at tmecorp.com>>
> wrote:
> I definitely agree with that suggestion, versus reinventing the
> wheel. Our experience with the RMI tool is that it works. There seems to
> be a quirk regarding a little shifting due to DST, but that’s a very small
> thing in the grand scheme of things. I want to say we tested it and the
> annual average value coming out of eQuest was ~ 99.3% of the average input
> value. Close enough! J
>
>
>
> Also, I don’t know if you are modeling the other buildings because
> a GBCI reviewer said you had to do that (assuming this is a LEED project)
> in order to ensure that correct part load ratios on the chillers operating
> profile are appropriately accounted for. I got that sort of comment on a
> recent project and my response was something to the effect of … I could do
> that, but since we aren’t getting paid by the owner to model buildings
> outside of the project scope just to make the chiller modeling more
> accurate, instead I will just use the default efficiency allowed by the
> DESv2.0 guidelines for water cooled chiller plants à 4.4 COP + 5%
> losses = ~ 0.839 kW/ton on average.
>
>
>
> That saved a lot of time with that change because if you do that,
> you don’t have to model any other buildings served by the system. If you
> are comparing against air cooled equipment for the Baseline, you still get
> a decent amount of savings. I probably left some savings on the table
> because the plant had high efficiency VFD water cooled chillers, and VFDs
> on the pumps and cooling tower. I’m positive that the annual efficiency
> was much better than 0.839 kW/ton, but (the way I look at this) we have to
> balance the level of effort on energy modeling versus the fees we are
> getting for the modeling.
>
>
>
> Hope this helps! J
>
>
>
> Regards,
>
>
>
> *JAH*
>
>
>
> *James A. Hess, PE, CEM, BEMP*
> Energy Engineer
> TME, Inc.
> Little Rock, AR
>
> Mobile: *(501) 351-4667* <%28501%29%20351-4667>
>
>
>
> *From:* *equest-users-bounces at lists.onebuilding.org*<equest-users-bounces at lists.onebuilding.org>
> [mailto:*equest-users-bounces at lists.onebuilding.org*<equest-users-bounces at lists.onebuilding.org>]
> *On Behalf Of *Javed Iqbal
> * Sent:* Thursday, March 28, 2013 1:55 PM
> * To:* Kimberly Wiebe
> * Cc:* *equest-users at lists.onebuilding.org*<equest-users at lists.onebuilding.org>
> * Subject:* Re: [Equest-users] CHW loop process load
>
>
>
> You should use RMI tool to generate schedule which will eventually
> gives you schedule in INP format.
>
>
>
> Here is the link to download it..
>
>
>
> *http://www.rmi.org/Content/Files/EMIT1.4.zip*<http://www.rmi.org/Content/Files/EMIT1.4.zip>
>
> On Thu, Mar 28, 2013 at 1:41 PM, Kimberly Wiebe <
> *Kimberly.Wiebe at burohappold.com* <Kimberly.Wiebe at burohappold.com>>
> wrote:
>
> Hello,
>
>
>
> I am modelling a central cooling plant that serves many buildings
> on an college campus. For some buildings I am building the geometry and
> inputting internal gains. For other buildings I have annual 8760 cooling
> load profiles. If I want to add these annual cooling load profiles to the
> CHW loop as process loads, would I have to make 365 day schedules (and 52
> weeks)? If so I will write some sort of text generator out of an excel file
> and paste in the .inp, but before I do want to see if there was any other
> way.
>
>
>
> Thank you,
>
> Kim
>
>
>
> *Kim Wiebe*
>
> Direct: *+1 310 945 4813* <%2B1%20310%20945%204813>
>
> *kimberly.wiebe at burohappold.com* <kimberly.wiebe at burohappold.com>
>
>
>
>
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>
> --
>
>
>
>
>
> Javed Iqbal, LEED AP, CEA
>
> Energy Analyst
>
>
>
>
>
>
>
>
>
>
>
>
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