Addition, or Separate Building?

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Hello Group,

I am modeling an existing building which could be seen as two buildings
connected by a short hallway. The quick story on this facility is that
there were two buildings which were connected by hallways at some point, and
are now on the same chilled and hot water systems. I'm having trouble
finding a clear definition in 90.1 which tells me whether I should be
modeling this as one building or two with a shared energy plant. This is
not a LEED project; I am only interested in a 90.1 interpretation.

Does anyone know of any clarifications, interpretations, or past experience
which could help guide me?

Thanks,

Christian

Christian Kaltreider's picture
Joined: 2011-09-30
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90.1 is flexible to model only one building or as a combined building, the determinant is what the client's purpose is in deciding to have an energy model project completed.

You could obviously model the whole complex with the specific central plant equipment, or else a single building could be modeled using district energy sources for heating and cooling depending on what the goal was for the study.

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

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I agree completely.

Let the scope/purpose of your modeling efforts decide whether modeling both building as one model is going to be beneficial.

Best regards,

NICK CATON, P.E.

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I'm seeing enough typos in my last reply to warrant a re-issue (following)... sorry for any confusion!

I agree completely.

Let the scope/purpose of your modeling efforts determine whether modeling both buildings as one model is going to be preferable. 90.1 leaves this kind of decision up to the modeler.

Best regards,

NICK CATON, P.E.

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Interesting, thanks for the helpful responses. I can move forward from
here.

Thanks,

Christian Kaltreider, LEED AP

Christian Kaltreider's picture
Joined: 2011-09-30
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I have to ask the "devils advocate" question...if you put two steering wheels, gas/brake pedals in a car, do you make it to your destination? I think it may come down to which building is the dominate utility user. If you are modeling the bigger building that may have more internal loads then the purpose of modeling the smaller building may just be an effort wasted. But if it was the opposite way around, then the larger load building may affect where your boiler/chiller operating points are. Don't assume that you are where you think you are at when looking at the equipment curves, they are together on the same system. Also in 90.1 Appendix G, you do have an exception for using more than one type of baseline if the space is more than 20,000sq. ft. Under Appendix G Table G3.1 Item 2. says that you may exclude en existing building if it is under it's own plant and has an entirely sperated system. There's a few more exceptions, but this was the major one I thought pertained to your question.

Be Sustainable -- Never let today use up tomorrow!.

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