Another little "inconvenient" is, since we are talking about a really big project, model software was somewhat unable tu run the complete model, so we split it into 2 different energy models. We are obviously going to submit all corresponding documentation (1.4 table, energy reports) for both models, but could this be subject to be flagged during the review?

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David Eldridge

Energy Efficiency Ninja

Grumman/Butkus Associates

LEEDuser Premium Member

64 thumbs up

Mon, 02/18/2019 - 22:41

It could be separate - even though it is owned by the hotel, the use and schedule of it will be different than the rest of the facility. You may see the hotel design case also have separate systems for the retail section. What software program are you using? Many programs allow the use of "multipliers" in case you have some typical zones that could be modeled once and multiplied in case this helps you. You may also be able to combine some zones that are equivalent (90.1 includes some guidance on what can be combined) if you are hitting a limit on number of zones. Splitting the model may cause some inaccuracies for fan systems that serve the whole building, or if the design case uses central heat or cooling.

Jorge Lopez de Obeso

Architect / Environmental adviser

eosis Consulting

LEEDuser Basic Member

20 thumbs up

Mon, 02/18/2019 - 23:27

Actually I considered maybe making all system 2 and just use different schedules for hotel/retail section. Mostly because, at least in proposed, they do have the same central cooling equipment. Could this be the most effective way? The HVAC System is fan and coil units connected to water cooled chillers, and chillers connected to their respective cooling tower. Fan and coil units are provided by the hotel in owned areas such as: Service zones (administrative offices, guest amenities, and conference rooms) Guest units Retail main corridor. (Retail locals are being provided with chilled water piping terminals and tenant will be instructed via TSLA what kind of units they might install). Spliting it may indeed cause some inaccuracies mostly in chiller performance. Since I was thinking modeling the exact same system but assigning the gpm's according to corresponding zones. Knowing that this is not as accurate as I would like to. I'm using eQuest, and yes, I already multiplied the 20x storys and combined guest units un 4 sections according orientation. The thing here is, project features plenum spaces and eQuest makes 1 plenum per zone, so basically the "double" zones are crashing it. Project is simply too big and complex. Thought it would be accepted claiming "software limitation" since it is unpractical to have one model.

Marcus Sheffer

LEED Fellow

7group / Energy Opportunities

LEEDuser Expert

4454 thumbs up

Tue, 02/19/2019 - 14:58

You are required to apply any of the exceptions to G3.1.1 if they apply. If the non-residential is over 20 k sf then (a) applies. If not then you technically should model a system #2 everywhere. You will definitely need a very thorough justification for combining two separate models. You can do so only if you can justify that doing so will produce a conservative result.

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