[Equest-users] Excessive summer heating

Coles Jennings C.Jennings at ha-inc.com
Fri Mar 6 10:07:23 PST 2015


Amy,

Even though it is 100% OA, is it constant volume? The min-flow-ratio applies to total supply air for each zone, not just outside air. If min-flow-ratio is set to 1.0, then the VAV unit will never reduce its supply flow and you will certainly  have a lot of summer reheat.

Thanks,

Coles Jennings, PE, BEMP, LEED AP BD+C
Senior Associate
Sr. Energy Engineer, Building Sciences Studio Manager

H&A | Hankins & Anderson | www.ha-inc.com<http://www.ha-inc.com>
d: (804) 521-7045 p: (804) 285-4171 f: (804) 217-8520

From: Harmon, Amy [mailto:aharmon at sbmce.com]
Sent: Friday, March 06, 2015 12:51 PM
To: Coles Jennings; Singhal, Harshul; equest-users at lists.onebuilding.org
Subject: RE: Excessive summer heating

Hi Coles!
I have a 100% OA unit.  I had to increase the reheat to decrease unmet heating hours.

Amy Harmon
Mechanical Engineer
Scheeser Buckley Mayfield LLC
1540 Corporate Woods Parkway
Uniontown, OH 44685
Phone: (330) 896-4664 ext. 107
Direct: (330) 526-2707
Fax: (330) 896-9180

From: Coles Jennings [mailto:C.Jennings at ha-inc.com]
Sent: Friday, March 06, 2015 11:41 AM
To: Harmon, Amy; Singhal, Harshul; equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: RE: Excessive summer heating

Amy,

The min-flow-ratios for your VAV zones are 1.00, meaning airflow is never reduced to those spaces. Check the "Air Flow" drop-down in the air-side zone spreadsheet, and check the Min Flow Ratio column. This explains the high amount of summer reheat.

Also, your VAV reheat coils are set to 50°F reheat delta T, which is very high.

Thanks,

Coles Jennings, PE, BEMP, LEED AP BD+C
Senior Associate
Sr. Energy Engineer, Building Sciences Studio Manager

H&A | Hankins & Anderson | www.ha-inc.com<http://www.ha-inc.com>
d: (804) 521-7045 p: (804) 285-4171 f: (804) 217-8520

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Harmon, Amy
Sent: Friday, March 06, 2015 11:29 AM
To: Singhal, Harshul; equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: Re: [Equest-users] Excessive summer heating

Hi Harshul!
Thanks for the response, it's not the unmet heating hours I'm too concerned about it unless something I did previously has caused the summer excessive heating.
The LEED reviewers commented that report PS-A & PS-B showed an excessive amount of heating during the summer months...in the month of July the heating load of 269 MBTUs of heating roughly 20.9% of the total heating and cooling load (269 MBTU + 1018.7 MBTU).

Amy Harmon
Mechanical Engineer
Scheeser Buckley Mayfield LLC
1540 Corporate Woods Parkway
Uniontown, OH 44685
Phone: (330) 896-4664 ext. 107
Direct: (330) 526-2707
Fax: (330) 896-9180

From: Singhal, Harshul [mailto:HSinghal at ThorntonTomasetti.com]
Sent: Friday, March 06, 2015 10:32 AM
To: Harmon, Amy; equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: RE: Excessive summer heating


Hi Amy,



The current model (you sent) has 172 unmet load hours coming from zone: "EL5 SSW Perim Zn (G.SSW2)"



I gave a real quick look at model and as per LEED it looks fine to me. DO you mean to decrease these unmet load hours or you already made changes and sent the model here at eQuest group?



I would say check SS-R report and see what zones have unmet load hours & you can increase supply CFM in those particular zones.

Best,
Harshul Singhal, LEED AP BD+C
Project Consultant
Thornton Tomasetti
386 Fore Street, Suite 401
Portland, ME  04101
T +1.207.245.6060  F +1.207.245.6061
D +1.207.245.6074
HSinghal at ThorntonTomasetti.com<mailto:HSinghal at ThorntonTomasetti.com>
www.ThorntonTomasetti.com<http://www.ThorntonTomasetti.com>

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Harmon, Amy
Sent: Friday, March 06, 2015 9:58 AM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: [Equest-users] Excessive summer heating

I received comments back from the LEED reviewers; they comment that I have excessive summer heating.  Prior to submitting to USGBC, I had already fooled with the throttling range and system cooling control to warmest.  Tweaking those helped with the unmet heating hours I had previously.  Could messing with those 2 items before have caused the excessive summer heating?  Any suggestions to lower the excessive summer heating?  I've attached the inp and pd2 file.  I'm running version 3.64.
Any help is appreciated.  Thanks!

Amy Harmon
Mechanical Engineer
Scheeser Buckley Mayfield LLC
1540 Corporate Woods Parkway
Uniontown, OH 44685
Phone: (330) 896-4664 ext. 107
Direct: (330) 526-2707
Fax: (330) 896-9180
aharmon at sbmce.com<mailto:aharmon at sbmce.com>
www.sbmce.com<http://www.sbmce.com/>

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