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How do I model a cold dark shell for performance compliance?

asked 2015-04-30 16:06:28 -0600

Dustinl gravatar image

updated 2015-05-02 11:51:39 -0600

I've got an winery with 9,500sqft of administration shell to be finished later as a T.I. with a small cellar break area to be completed with the process area. What is the proper way to model the occupancy of the shell area to show performance compliance?

Is there a trick or special way to model "Unocupied Area" I continue to get a Zone Temp Set error?

I originally modeled the building in ENERGY PRO v6.5. and then brought the file into CBECC-COM. Energy plus is fairly new to me, however, I do intend to model all of my projects using it in the future. I am targeting 2015 T24 compliance, without LEED or other reach code.



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Welcome @Dustinl. Can you edit your question to include the software you're using and the compliance framework you're targeting, e.g. 90.1, LEED, T24, etc.

MatthewSteen gravatar image MatthewSteen  ( 2015-04-30 18:33:41 -0600 )edit

@Dustinl I replaced your tags with more informative ones.

MatthewSteen gravatar image MatthewSteen  ( 2015-05-02 11:53:55 -0600 )edit

2 Answers

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answered 2015-05-04 12:31:11 -0600

pflaumingo gravatar image

updated 2015-05-04 15:30:33 -0600

@Dustinl, I am going to assume in my response that all the lighting will be installed in the future as a TI because I am unsure whether it is just the administrative area, or the process/break area too.

I am not sure what version of CBECC-Com you are using, but CBECC-Com v3a and v3b have a compliance type "New Envelope". You can access this in CBECC-Com by double clicking on the 'Project' object and there is a drop down selection for the compliance type. If you do this, you will notice that the default lighting status at the space level is "future" rather than "new". The future status sets the LPD based on the space type selected making the baseline and proposed LPD the same, as well as enforcing the same daylighting controls. Simulating the lighting as if it were installed simulates zones with more accurate loads allowing for the HVAC systems to be simulated more accurately. For the HVAC systems, you need to make a dummy system that is the same as the baseline system and these details can be found in the non residential ACM linked in the next paragraph.

The answer regarding ASHRAE guidelines is not an acceptable method for Title 24 compliance as Title 24 does not follow the ASHRAE guidelines. Title 24 has it's own set of guidelines you should follow in the Title 24 non-residential alternative calculation method (ACM) manual that can be downloaded from here. If this manual does not describe your issue specifically then you should get in touch with the California Energy Commission (CEC) hotline if it is a questions regarding the energy code or if it is a question regarding CBECC-Com and how to model specific scenarios then you should submit an issue here.

Regarding unoccupied zones I would double check that both the zone and the space are set to unconditioned. If you could copy and paste the exact error (shown in full in the .log file) then it would be easier for us to advise. Alternatively, you can get in touch via the CBECC-Com specific link above and ask them directly for guidance.

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answered 2015-12-11 18:41:17 -0600

updated 2015-12-11 18:41:56 -0600

I know this response is late, but in case anyone has an issue similar to you, in cases like this it often makes sense to pursue prescriptive compliance. The most difficult metrics to meet for prescriptive envelope is the 40% WWR, and the window U-value and SHGC. If the project can meet those, they are very simple forms to fill out.

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Thanks Anna, I just saw your comment. On most of our projects we do have an issue with the WWR (+ most builders in my area like to build with metal studs and dislike using rigid insulation) so I typically show Perf-Env compliance which allows for trade-offs. This way we are set up in a good place when the TI takes place. This approach required modeling a "dummy" mechanical system that meet the prescriptive requirements in order to run compliance. I see now in the most recent software versions modeling a mechanical system is not required.

Thanks for your comment.

Dustinl gravatar image Dustinl  ( 2016-08-16 10:40:09 -0600 )edit

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Asked: 2015-04-30 16:06:28 -0600

Seen: 371 times

Last updated: Dec 11 '15