[Bldg-sim] Modelling diversity in single zone apartments

[Dru Crawley]

You may also want to look at the multifamily building models that PNNL uses
for evaluating 90.1 changes:

http://www.energycodes.gov/development/commercial/90.1_models

(towards the bottom of the table). The 'Scorecard' XLS shows all the inputs
and where there were derived.




On Sun, Dec 1, 2013 at 6:22 PM, Jim Dirkes
<jim at buildingperformanceteam.com>wrote:

> Patrick,
>
> Here are a few considerations:
>
> 1.       Apartments for working people will have low loads during the day
> and high loads at night.  The offices will have the reverse pattern.
> Depending on the actual office schedules, the actual residential occupancy
> pattern and the ratio of office / residential space, 50% might work very
> well.  50% may also be rather close to “irresponsible” unless the local
> population is very tolerant of room temperatures that are a few degrees
> higher than normal!
>
> 2.       Regardless of #1 above, a LEED project should model the building
> based on the architect and Engineer’s “Basis of Design” (BOD) document.
> The scheduling and diversity patterns I mention in #1 are not commonly part
> of a BOD document, but in your case they sound critical.  You should
> (strongly) request this information!  If you make assumptions that differ
> from the Engineer’s you may spend endless hours trying to reduce unmet
> cooling load hours (and probably will not get paid for them)
>
> 3.       Once you are confident of the schedules that have been assumed
> by the BOD, you should be able to represent them for the energy model.
>
>
>
> Note: Because each apartment has two fan coils, each with a thermostat,
> you really have two zones.  This may become important for the cooling
> diversity.
>
>
>
> *James V Dirkes II, PE, BEMP, LEED AP*
> *www.buildingperformanceteam.com*<http://www.buildingperformanceteam.com/>
> *Energy Analysis, Commissioning & Training Services*
> 1631 Acacia Drive, Grand Rapids, MI 49504 USA
> 616 450 8653
>
>
>
> *From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
> bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Aaron Smith
> *Sent:* Friday, November 29, 2013 6:49 PM
> *To:* Patrick Bivona; bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] Modelling diversity in single zone apartments
>
>
>
> Patrick,
>
>
>
> I suspect they didn't assume that the bedroom wasn't cooled at the same
> time as the living room. They may have assumed that the cooling schedule of
> the office space is different than the apartments - maybe 8am to 5pm M-F
>  for the offices and close to the opposite for the apartments. Or they may
> have determined that the building peak load was 50% of the sum of the
> individual loads. A more likely scenario would be that the combined affect
> of both of those might equal 50%.
>
>
>
> I don't think it would be acceptable to turn cooling off in half of the
> apartments even if you did the same thing in the Baseline building. Are you
> running into issues with the chiller being undersized?
>
>
>
> Aaron
>
>
>
>
>
> *From: *Patrick Bivona
>
> *Sent: *Thursday, November 28, 2013 23:32
>
> *To: *bldg-sim at lists.onebuilding.org
>
> *Subject: *[Bldg-sim] Modelling diversity in single zone apartments
>
>
>
> Hi all,
>
>
>
> I'm modelling a mixed office/residential tower building with 160
> apartments in tropical climate, for LEED. The apartments are centrally
> cooled with fan coil units, in the living room and bedrooms. The design
> team sized the chiller with a diversity of 0.5, probably assuming that when
> the occupants are in the living room, they're not cooling the bedrooms or
> something of the sort.
>
>
>
> Given the number of apartments, I modelled each apartment as a single
> block. I cannot use zone multipliers because of the specific geometry of
> the building. I have one combined FCU for each apartment, which is of
> course either on or off. I'm also grouping apartments based on orientation,
> but that's beside the point.
>
>
>
> My question is about an approach to modelling the diversity of use of FCUs
> in the apartments. With my modelling simplification, I cannot model the
> diversity of cooling within an apartment. So what would be an acceptable
> approach?
>
>
>
> I can only think of turning cooling off in half of the apartments, though
> apartments with cooling turned off are occupied and have internal loads.
> Would a LEED reviewer be ok with such an approach. Or is there a better way?
>
>
>
> Thanks,
>
> Patrick
>
>
>
>
>
>
>
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