[Equest-users] Can't get unmet hours under control for cooling

Nick Caton ncaton at smithboucher.com
Fri Jun 8 15:55:39 PDT 2012


Jamie:

Aside from ongoing advice by others, I've had a chance to give the most recent set of models a scan.

I notice you have a relatively large amount of exterior lighting.  I also notice your proposed and baseline installed wattage and scheduling are identical.  Think that through carefully!  If you didn't do the electrical/lighting/associated controls for the project yourself, reigning that individual into the brainstorm may be productive.  My LEED models rarely feature identical exterior lighting consumptions, and in your particular case this is likely low hanging fruit to improve your modeled performance towards your target.

More low fruit:  I also notice your process loads are eerily close to the ubiquitous 25% mark...  I hope that's coincidence!  Consider your sources carefully and whether your inputs are appropriate for an energy model (vs. sizing equipment).  Following recommended plug load densities in the 90.1 Users Manual (0.75W/SF for office buildings), I experimentally find your misc. equip. annual consumption drops about 7MWh - this would mirror for both models and in turn amplify the differences/improvements of all other systems.  A quick visual check confirms using the prescribed receptacle usage schedule from the same source will net you further trimming in this department.

To the most recent query about gas costs:  All things being equal (and perhaps they shouldn't be), I see the proposed isn't consuming a great magnitude of extra gas, and this can be normal.  For this scale of project, you might well explain the additional proposed consumptions entirely by the difference in lighting LPD contributions for internals during the winter months.  I would advise not getting too hung up on this fact, but if you want to feel confident I'd advise checking your heating efficiencies are correctly entered for both models and that the rates are identical.


[cid:image001.png at 01CD4599.CA174D50]
[cid:image002.png at 01CD4599.CA174D50]

[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: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Armstrong, Jamie
Sent: Friday, June 08, 2012 8:14 AM
To: Umesh Atre; Howe, Timothy; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Can't get unmet hours under control for cooling

I've finally got the unmet hours under control but my heating costs are more in my design than my baseline.  I'm shooting for 24% increase in efficiency and I'm at 4 now.

My design system is a PSZ with natural gas heat.

Jamie Armstrong P.E.
Mechanical Engineer

[Description: Description: image001]

v. 210.546.0200 | www.dbrinc.com<http://www.dbrinc.com>

From: Umesh Atre [mailto:umesh at innovativedesign.net]
Sent: Friday, June 08, 2012 8:00 AM
To: Armstrong, Jamie; Howe, Timothy; equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: RE: [Equest-users] Can't get unmet hours under control for cooling

Jamie,
Is there a reason you have all the plenum spaces on their own separate system with indoor design temperatures similar to your conditioned zones?




________________________________
From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Armstrong, Jamie
Sent: Thursday, June 07, 2012 6:20 PM
To: Howe, Timothy; equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: Re: [Equest-users] Can't get unmet hours under control for cooling
In regards to OA for PSZ RTU's.

When allowing eQuest to autosize the airflow to each space if you set a ratio of OA to supply air whatever eQuest calculates the supply air needed for that space will vary the outside airflow.

If I enter the OA at the zone level to each space how do you set up a schedule for the OA?  Based on Timothy's answer I would need a different schedule for each RTU with its ratio of OA to supply air.  I wanted the MinOA schedule to be an on/off flag to deliver the OA that I put in at the zone level according to the occupied schedule.



Jamie Armstrong P.E.
Mechanical Engineer

[Description: Description: image001]

v. 210.546.0200 | www.dbrinc.com<http://www.dbrinc.com>

From: Howe, Timothy [mailto:Timothy.Howe at stantec.com]
Sent: Thursday, June 07, 2012 3:51 PM
To: Armstrong, Jamie; equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: RE: Can't get unmet hours under control for cooling

Jamie,

You have some inconsistencies in your inputs for the OA on system RTU-2 (and all the rest).  See highlighted area below.  You are saying that the system is 100% recirc by setting the Minimum Outside Air ratio to 0.00, but your Minimum Air Schedule (note that this is a fraction of the design supply CFM type of input) is saying otherwise and takes precedence causing it to be a 100% OA system.  See my snip from the hourly reports below too.  You need to develop the proper ventilation rates for each system and verify with hourly reports.  Do not rely on the summary tab in the air side system tab of eQUEST to give you correct data at all times.   If you just define the OA by using the Minimum Outside Air ratio, you will be supplying OA every time the fan operates.  To prevent this you need to set up Minimum Air Schedule for each system which is based upon the proper fractions for that system.

[cid:image008.png at 01CD4599.CA174D50]


[cid:image009.png at 01CD4599.CA174D50]




Timothy Howe, MS, LEED® AP BD+C
Mechanical Engineer
Stantec
61 Commercial Street
Rochester NY 14614
Ph:   (585) 413-5347
Fx:   (585) 272-1814
Cell: (585) 330-8681
stantec.com<http://www.stantec.com>

The content of this email is the confidential property of Stantec and should not be copied, modified, retransmitted, or used for any purpose except with Stantec's written authorization. If you are not the intended recipient, please delete all copies and notify us immediately.

ü Please consider the environment before printing this email.
From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Armstrong, Jamie
Sent: Thursday, June 07, 2012 4:23 PM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: [Equest-users] Can't get unmet hours under control for cooling

I need some help getting these cooling unmet hours under control.  I have to get this model complete and submitted by tonight.

We've tried multiple things to try to get the model to work out.

We've tried the following:

·         Letting eQuest autosize the heating and cooling for the PSZ units

·         Verified that the schedules are consistent with both cooling, heating, and occupancy.

·         On the baseline building we have the min cfm set to 0.5 for most spaces and 1 cfm/sf for some of the larger spaces.

·         We set the PSZ -fan - flow parameter - indoor fan mode to intermittent to get the unit to show partial capacity thru out the days.

One item is RTU-2 in my model.  It serves only one space.  We have a high amount of unmet hours on this and we are letting it auto size the capacity and airflow and it still says its not staying under control.  We're assuming that we are missing one small check box that's somehow causing these unmet hours.

I've attached the pd2 files for both baseline and proposed along with weather data and inp files.

Thanks in advance for any help!


Jamie Armstrong P.E.
Mechanical Engineer

[Description: Description: image001]

v. 210.546.0200 | www.dbrinc.com<http://www.dbrinc.com>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120608/71594826/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 11462 bytes
Desc: image001.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120608/71594826/attachment-0008.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.png
Type: image/png
Size: 10624 bytes
Desc: image002.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120608/71594826/attachment-0009.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image006.jpg
Type: image/jpeg
Size: 1459 bytes
Desc: image006.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120608/71594826/attachment-0004.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image007.jpg
Type: image/jpeg
Size: 4860 bytes
Desc: image007.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120608/71594826/attachment-0005.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image008.png
Type: image/png
Size: 27954 bytes
Desc: image008.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120608/71594826/attachment-0010.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image009.png
Type: image/png
Size: 63033 bytes
Desc: image009.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120608/71594826/attachment-0011.png>


More information about the Equest-users mailing list