[Bldg-sim] [Equest-users] Lesson Learned: Single Zone Packaged DX vs. Packaged VAV system types

[David Wood]

Kristy,
Is the cool control in the PVAVS system set to constant (the default)?  If
the answer is yes, you are always cooling 100% of the supply air to the
MIN-S-T unless cooling is scheduled off.  Of course this will require
substantially more cooling and reheat then a PSZ system that cools to the
temp required  by the control zone. I am not sure if you are comparing
apples to apples.
DW

On Tue, Jan 17, 2012 at 6:20 PM, Dahlstrom, Aaron
<ADahlstrom at in-posse.com>wrote:

> Kristy- ****
>
> ** **
>
> Did you try to use the “WASTE-HEAT-USE” feature of the PSZ system for
> humidity control?****
>
> ** **
>
> ****
>
> ** **
>
> I’ve had success using this feature to achieve the desired space humidity
> conditions with 100% OA units.****
>
> ** **
>
> I can’t remember whether its energy performance is appropriate, but I did
> verify with hourly reports that the zones in question had accurate humidity
> control.****
>
> ** **
>
> I remember having a hard time finding this feature – several late nights
> with the DOE-2 dictionary – but I eventually found the documentation on Vol
> 2 – Dictionary – pp398-399 and pp416-417.****
>
> ** **
>
> *Aaron Dahlstrom , PE, LEED® AP*****
>
> *In P**o**sse* – 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 *Walson, Kristy
> *Sent:* Tuesday, January 17, 2012 2:47 PM
> *To:* 'equest-users at lists.onebuilding.org'
> *Subject:* [Equest-users] Lesson Learned: Single Zone Packaged DX vs.
> Packaged VAV system types****
>
> ** **
>
> Hi all,****
>
> ** **
>
> I just wanted to share a lesson learned that I ran across recently while
> using Equest.  Here are the pertinent specs for the building:****
>
> ** **
>
> **·         **Proposed Case****
>
> **o   **65,000 sq ft of laboratory (with ac/hr requirements)****
>
> **o   **Cooling is provided by a chilled water district plant****
>
> **o   **Heating is provided by a district steam boiler plant****
>
> **o   **100% outdoor air****
>
> **o   **Humidity control is being utilized****
>
> **·         **Baseline****
>
> **o   **Per G3.1.1 Exception (c), baseline system type is #3, Packaged
> DX, Constant Volume, Fossil Fuel Furnace****
>
> **o   **Humidity control is included because it’s in the design case
> (ASHRAE 90.1-2007 Table G3.1 Part 1.b)
> [image: cid:image002.png at 01CCD519.AEAE29D0]****
>
> **o   **100% outdoor air, or a percentage to match the proposed****
>
> ** **
>
> Because the ASHRAE baseline system was #3, I used the Equest system type
> “Packaged Single Zone” for the baseline model and then proceeded to pull my
> hair out for a day because the baseline model was performing better than
> the proposed.  Then I decided to try changing the baseline system type to
> “Packaged VAV” and setting the fan control to “Constant” with the minimum
> flow ratio set to “1”, in order to force it to still be a constant volume
> system.  The first thing I noticed after *only* changing the system type
> was that the cooling energy almost doubled.  The upshot is the following,
> for these Equest system types:****
>
> ** **
>
> **·         **Packaged Single Zone****
>
> **o   **When you add reheat in order to control humidity, the software
> shows an increase for the heating energy, but does not show an increase in
> cooling energy.  Cooling energy should also increase because it now has
> additional heat due to reheat to overcome.  The place to verify humidity
> control is the *SS-N report*, which showed that humidity was not being
> controlled, despite the fact that I had set the maximum humidity to 60% in
> the inputs.****
>
> **·         **Packaged VAV****
>
> **o   **When you add reheat, the software shows an increase in both
> heating and cooling energy.  *This is correct*.  Otherwise, your baseline
> building will always perform better than the proposed.  Again, verify that
> humidity is being controlled in the *SS-N report*.****
>
> ** **
>
> *LESSON LEARNED:  Always use the Packaged VAV system type in Equest when
> modeling DX equipment. * If you have a constant volume system, just
> adjust the fan control to be “Constant” and the minimum airflow ratio to be
> “1”.  ****
>
> ** **
>
> I hope this makes sense.  Feel free to comment if you’ve had experience
> with this.  Thanks!****
>
> ** **
>
> *Kristy M. Walson, PE, LEED AP BD+C, BEMP*
>
> *Associate / Sustainability Consultant*
>
> ** **
>
> *TLC Engineering for Architecture
> **Your 2030 Challenge Partner***
>
> ** **
>
> 255 South Orange Avenue, Suite 1600****
>
> Orlando, FL 32801-3463****
>
> ** **
>
> phone: ****
>
> 407-841-9050****
>
> fax: ****
>
> 407-425-7367****
>
> direct: ****
>
> 407-487-1118****
>
> website: ****
>
> www.tlc-engineers.com****
>
> ** **
>
> [image: http://www.tlc-engineers.com/images/TLC_Sig_Loc_Block.gif]<http://www.tlc-engineers.com/>
> ****
>
> ** **
>
> This e-mail may contain information that is confidential, privileged or
> otherwise protected from disclosure. If you are not an intended recipient
> of this e-mail, do not duplicate or redistribute it by any means. Please
> delete it and any attachments and notify the sender that you have received
> it in error. Unintended recipients are prohibited from taking action on the
> basis of information in this e-mail. E-mail messages may contain computer
> viruses or other defects, may not be accurately replicated on other
> systems, or may be intercepted, deleted or interfered without the knowledge
> of the sender or the intended recipient. If you are not comfortable with
> the risks associated with e-mail messages, you may decide not to use e-mail
> to communicate with In Posse.
>
> _______________________________________________
> Bldg-sim mailing list
> http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
> To unsubscribe from this mailing list send  a blank message to
> BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG
>
>


-- 
David S. Wood
Principal, WB&A
wk:  610.347.0710
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20120119/ff47a053/attachment-0002.htm>