unmet heating load hours

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I have a Costco warehouse equest model with 4 unmet heating load hours in my proposed model with zero in my baseline budget model. I need to be able to tweak my model to get rid of these unmet load hours but minor tweaks don't seem to make a difference. Could there be something wrong with the model that results in having a few unmet load hours that are hard to get rid of?

Tim Burke

T.E., Inc.
830 North Riverside Drive #200
Renton, WA. 98057
(425) 970-3753 Phone
(425) 970-3756 Fax
WWW.TEI-ENGINEERING.COM
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via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

Four hours doesn't seem unreasonable...you are referring to a requirement to not have more unmet hours in the proposed than the baseline?

My suggestion is to take a look and see when these hours are occurring to try and find a common theme - what's the occupancy then, time of day where the spurious hours could be at start-up or later in the main shift, or during a lightly occupied time?

This might lead you to identify an equipment capacity constraint or else a tweak to the control scheme in use for the zone(s).

David

David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
Grumman/Butkus Associates

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

Agreed on all points. Is 4 a typo? I'd consider that a pretty darn comfortable building if not!

Adding some (unasked for) perspective: Unmet hours do not always mean the model inputs/outputs are incorrect. Real buildings are not always comfortable, and expectations/thresholds of comfort for occupants are not static/binary. On the flip side of the coin: a "correct" model (approaching calibrated reality in behavior) might attract my critical eye if it's reporting absolutely zero unmet hours in the baseline / proposed case. Then again... I work a lot on buildings with comfort issues to resolve, so maybe that's just par for the course!

The airside summary reports are where I'd start to help isolate the exact zone(s) reporting this (tiny) number of unmet hours, spatially & by system. The detailed reports can from there inform you what time of day those hours occur, and if need be you can dig into hourly custom reports to drill down whether the source is in system capacities (airflow, heating), system operations (see schedules, night cycling inputs, lockouts), unrealistic internal/envelope loads, or else due to the need for thermostat tweaks (setpoint/setback schedules, building warmup, whether a thermostat should be in the zones of concern to start with...). I'd spitball 9 times out of 10 it's some combination of those issues for of unmet hours in relatively small quantities.

As an option, you can share a copy of your project with the list also and potentially gather some others' hands-on perspectives. Include the INP + PD2, and indicate the climate/weather location as well if it isn't referenced from doe2.com. Include the PRD if parametric runs feed into your concerns.

~Nick

[cid:image001.png at 01D2BF81.82049330]
Nick Caton, P.E., BEMP
Senior Energy Engineer
Regional Energy Engineering Manager
Energy and Sustainability Services
Schneider Electric

D 913.564.6361
M 785.410.3317
F 913.564.6380
E nicholas.caton at schneider-electric.com

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

[cid:image002.png at 01D2BF81.82049330]

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

Thanks a lot, I think I'll take those suggestions. I'm guessing it needs a smoother transition up to temperature from night time so I'm working on the temperature set point schedule.

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

Hi Tim,

For LEED projects the unmet load hour can go up-to 300 hours for the
Baseline Case and the unmet hours in the proposed case shall not exceed the
unmet hours in the base case by more than 50 hours.

However in order to remove unmet load hour you can tweak with the heating
set-points to higher limits, changing the control zone to more larger
spaces, might be increasing the throttling range to 8 degree Fahrenheit and
so on.
May be this can help.

*Thanks,*
Sharad.Kumar.

---------- Forwarded message ----------
From: Tim Burke via Equest-users
To: "equest-users at onebuilding.org"
Cc:
Bcc:
Date: Thu, 27 Apr 2017 21:50:15 +0000
Subject: [Equest-users] unmet heating load hours

I have a Costco warehouse equest model with 4 unmet heating load hours in
my proposed model with zero in my baseline budget model. I need to be able
to tweak my model to get rid of these unmet load hours but minor tweaks
don?t seem to make a difference. Could there be something wrong with the
model that results in having a few unmet load hours that are hard to get
rid of?

Tim Burke

T.E., Inc.

830 North Riverside Drive #200

Renton, WA. 98057

(425) 970-3753 Phone

(425) 970-3756 Fax

WWW.TEI-ENGINEERING.COM

This message contains information that is confidential or privileged. The
information is intended for the use of the individual or entity named
above. If you are not the intended recipient, be aware that any disclosure,
copying, distribution or use of the contents of this information is
prohibited. If you have received this electronic transmission in error,
please notify the sender and delete this message and any attachments

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

8 degF (4.44 degC) looks too high to me. The following standard holds true
for all irrespective of tool used (Eplus, eQuest. IES VE etc.), in my
opinion.

[image: Inline image 2]

source: 90.1-2010 Performance Rating Manual

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

Hi Javed,

It can be that you are right but i know lesser about energy plus.
I think that this part is of some software manual which wants to describe
that if the load are unable to match up-to the extent that the unmet load
hours are not limited by the maximum capacity then you are supposed to use
other means to meet down the throttling hour or UMLH (unmet load hours).

As per this guideline one is required to have throttling range upto 2
degree Fahrenheit.

As per me this is regarding energy plus software.

*Thanks,*
Sharad.Kumar.

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200