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How to troubleshoot unmet hours for my model?

asked 2015-05-29 13:28:19 -0500

Brian C's avatar

updated 2017-05-17 12:48:25 -0500

A true unmet hours questions...

My model currently have 3,000+ unmet occupied hours during cooling. Yikes!...I have searched through my model and nothing seems to jump out as the culprit. Is there perhaps a common mistake I may be making? Any suggestions? My HVAC system is quite basic: VAV air system, HW condensing boiler, and an air-cooled chiller. Thanks!

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Not sure what simulation energy you are using. If EnergyPlus then check out this post.

David Goldwasser's avatar David Goldwasser  ( 2015-05-29 13:59:33 -0500 )edit

Thanks! I appreciate the help

Brian C's avatar Brian C  ( 2015-05-29 14:19:44 -0500 )edit

@Brian C can you please add a tag for the simulation tool you are using? "openstudio"? "energyplus"? "equest"?

Neal Kruis's avatar Neal Kruis  ( 2015-05-29 14:27:47 -0500 )edit

will do, sorry about not specifying that information

Brian C's avatar Brian C  ( 2015-05-29 14:45:21 -0500 )edit

why does the design day file get erased when you save an .OSM file? I have them saved in the same location but only my EPW file is recognized and remains in the files folder...

Brian C's avatar Brian C  ( 2015-05-29 14:50:29 -0500 )edit

4 Answers

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answered 2015-05-29 15:10:02 -0500

Coming soon to a reporting measure near you...

image description

David and Andrew have been working on significant reporting improvements, of which this is a part. This will show up first as a new reporting measure on the BCL in the next couple weeks, and will likely be integrated in the OS App as the new standard report in release 1.8.1.

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Is there something similar available for time of day? I would find that very useful.

Lincoln's avatar Lincoln  ( 2015-06-25 14:57:20 -0500 )edit

answered 2015-07-21 11:34:52 -0500

Just to follow up on @ljbrackney's answer, the expanded reporting measure was included in OpenStudio 1.8.1, and also put on BCL (for use with OpenStudio 1.7.5 or later). The BCL link is on the documentation page for the measure. You can download 1.8.1 from our developer page.

We will continue to polish it for 1.9.0, and may make other modifications. For example it might be nice to break unmet hours for a zone down by occupied vs. un-occupied times.

@Lincoln, you may look at the unmet load hours troubleshooting measure that @Eric Ringold pointed out if you want to see specific times of day, PSD did a great job making this. It overlays zone temperatures and setpoints in interactive line plots that you can zoom in on, much like results viewer. Also since the new measure does request hourly zone temperatures you can always open the SQL file in Results viewer and create a flood plot to see temperatures binned by time of day and time of year. We also have examples of reporting measures that make flood plots.

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answered 2015-05-29 16:47:44 -0500

I've found this reporting measure to be very helpful, though the report generation can add some time to the simulation, especially for large models. Looking forward to the expanded capability @ljbrackney teased us with.

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+1, you beat me to it!

MatthewSteen's avatar MatthewSteen  ( 2015-05-29 16:51:14 -0500 )edit

answered 2015-07-21 22:01:01 -0500

hugopft's avatar

I Have Been working in the model to submit to LEED and I had a similar problem in some of my zones. Without see your model, I would bet that you are having problems in the beggining of the ocupation. So, try to start your HVAC system before the occupation starts. Another important point is to create a thermostat schedule in small steps, I mean, do not set the 30° C and then 23 ° C. Make this transition gradually in order to prepare your zones to receive ocuppation (and other loads). The most part of my problems, I solved using this two strategies.

Unfortunatly, I still have two zones of my reference model that are presenting a big amout of unmetloadhours. I already identified the problem: in both cases, the unmetloadhours are happen between 14:00 and 16:00 as shown in in the pictures below, seems that the system do not have enough capacity to control this (currently, I am using a throttling range temperature of 0.5K; the area between the red lines in the picture below).

Any advice to solve it?

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Asked: 2015-05-29 13:28:19 -0500

Seen: 731 times

Last updated: Jul 21 '15