Definition of a University Dormitory - Residential or Non-Residential?

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Dear Bldg Sim,

I'm looking for guidance on the definition of a University Dormitory building that I'm modeling under LEED 2009, particularly referencing Table G3.1.1A Baseline HVAC System Types. The building has 9 storeys above grade with an underground basement, with a total floor area of approx. 125,000 sq. ft.

The Basement is primarily crawlspace, electrical, mechanical, student storage etc.

The Main Floor consists of a number of multi-purpose rooms, further storage facilities for bicycles, recycling etc, with 1/3 of the main floor plan dedicated to student residences.

The remaining floors, 2 - 9, are student residences with a number of break out/study rooms/lounge areas on each floor.

Is the building classified as "Residential", or is it considered "Nonresidential and More than 5 floors or > 150,000 sq. ft" due to the basement and main floor spaces not being "Residential"? Will I have to model the basement and the main floor separate from floors 2-9?

Your help is greatly appreciated.

Cheers

D?nal

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Sir:
?
If the building is over 5 stories high believe that comes under Non-Residential. Period.
?
?
John Aulbach, PE

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However.....
The notes in that table clarify as shown below. I think the notes indicate that Donal's "predominant" building type is residential. It sounds as though there are some "non-predominant" types as well. Take a look at G3.1.1's Exceptions for a description of those.

Notes:
Residential building types include dormitory, hotel, motel, and multifamily. Residential space types include guest rooms, living quarters, private living space, and sleeping quarters. Other
building and space types are considered nonresidential

James V Dirkes II, PE, BEMP, LEED AP

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I would classify it as Residential. It would seem strange to have a
dormitory classified as non-residential. If the common areas qualify
under G3.1.1 then they would be modeled as system type 3 or 4.

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Per the exception noted by Mr Dirkes, I would model the Baseline building based on Table G3.1.1A; except with the dorm rooms, modeled them with System 1 or 2.

Here is how I come to this decision:

* Since your dormitory building contains some non-residential space types, you shouldn't use the building type to determine your Baseline, ie it's no longer truly a residential building type
* Dorm rooms still fall under the residential space type, so use residential Baseline systems (1 or 2) for those spaces
* "Other building and space types are considered nonresidential" This statement allows the rest of the building to be modeled per standard baseline (area, # of floors, energy source).

I see the same thought process applies to the mixed-use (commercial/apartments) as well. With the rise of mixed-use commercial building, I'm sure we'll be seeing this type of scenario more often. I welcome any comments or suggestions.

Thanks,

Rut Wattanasak
LEED AP BD+C

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D?nal,

Our team recently modeled a similar university dorm (Basement + Main floor with office spaces + four floors or residential units) for LEED 2009.

We determined that the Baseline should be based on "Residential" (as indicated by the note on Table G3.1.1A that says to use the predominant condition to determine the system type for the entire building) and used System 2 (electric-type heating in our Proposed case). For the common areas such as the office spaces in the first floor, you can use the same type of system (1 per zone) if they do not meet Exception G3.1.1a.

The LEED reviewers accepted our approach and we got our 8 points for that project EAc1.

Good luck,

[cid:image003.jpg at 01CE35F3.4F3AC620]Demba Ndiaye, Ph.D., P.E., LEED AP BD+C, BEMP

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Hi all,

Thank you for your responses thus far.

I did a quick calculation of the areas. Total Residential Floor area is approx. 75,000 sq. ft. and total Non-residential is approx. 50,000 sq. ft. The Non-residential areas include the basement, main floor multi-purpose rooms, lobbies, storage etc, and the common corridors, elec, janitor, lounge/study areas on Floors 2-9.

So if we are in agreement that the Residential areas are to use either System 1 or System 2, the next question is what are the Non-residential areas classified as? From Table G3.1.1A it appears the number of floors take precedence over the floor area, so as the Non-residential area extends over 10 floors, it should be classified as System 7 or System 8. Am I correct in saying that the number of floors takes precedence over the floor area?

Thanks again for your help and guidance.

Cheers

D?nal

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Those are support spaces for the residential and can just be the same
system type, as that?s the predominant space type. Anything else is
needlessly complicated. The enclosed document is useful for establishing
modeling inputs for residential projects.

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I second the approach described by Demba. Rut wrote ?Since your dormitory
building contains some non-residential space types, you shouldn't use the
building type to determine your Baseline, ie it's no longer truly a
residential building type?. I disagree that presence of spaces such as
electrical/mechanical rooms, corridors, stairs, multi-purpose rooms, etc.
automatically means that this is not a residential building type. It is hard
to imagine a dormitory, hotel, motel, or multifamily without these, and
System 7/8 is hardly an appropriate baseline for such spaces (there would
have to be a system modeled for each floor).

You should also remember that only the area of conditioned spaces as defined
in 90.1 Section 3 is counted when determining baseline system type (G3.1.1),
so spaces like electrical/mechanical or storage may not have to be factored
in.

Thanks,

Maria

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I vote with Maria and Demba :).
It is, however, very interesting to see all of the different perspectives!

James V Dirkes II, PE, BEMP, LEED AP

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Hi all,

I will model the building based on System 1/2 and group the spaces based on thermal zones.

Thanks for all of your help and guidance.

Cheers

D?nal

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Yet another perspective is that when high-rise residential buildings are
modeled with Systems 7/8 serving common spaces on each floor, even very
modest proposed designs, such as minimally code compliant PTACs, often show
hefty savings compared to the baseline because many of the prescribed
Appendix G settings and controls misfire (e.g. 0.4 cfm/sf minimum setpoints
for VAV reheat in G3.1.3.13). This is an issue for incentive programs that
use Appendix G protocol, because they end up with some pretty ridiculous
ECMs that on paper qualify for incentives.

Maria

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Good morning, all,

Yes, dormitories are residential spaces (remember this also affects your
baseline building envelope requirements). In this instance since the
non-residential spaces total more than 20,000 square feet, an alternate HVAC
system type should be selected for the predominant condition. Depending on
the operating schedules, internal loads, etc. (the other exceptions to
Section G3.1.1) using a third system type may be appropriate (type 3 or 4).
Whether it is appropriate to count the common areas on the residential
floors to determine the system type for the non-predominant condition could
be argued either way. Before proceeding either way, I would suggest looking
for any LEED Interpretations since the reviewer is likely to hold you to
previously published interpretations. I also believe mixed-use residential
projects are discussed in the Advanced Energy Modeling for LEED 2009 (free
to registered projects and available in LEED online under the credit
resources tab).

Hope this helps!

Cam Fitzgerald

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Hi Cam,

I agree with the others that the "non-residential" areas such as common corridors, janitor, elec rooms etc on Floors 2-9 are there to support the residential areas and therefore should be classified as "residential". The "non-residential" areas on the main floor and the basement total approx. 19,000 sq. ft. which is under the 20,000 sq. ft. threshold specified in G3.1.1 Exception (a), so I will specify all areas as "residential" and assign to System 1/2.

Thanks again for all of your responses.

Cheers

D?nal

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Hi D?nal,

The public spaces (common corridors, lounges, and utility spaces) on the
residential floors are classified as non-residential and must be modeled
with a non-residential system type if the total area for these spaces is
more than 20,000 square feet. You can try another approach, but it is likely
that the reviewer will require you to change the model if you use
residential systems in the public spaces.

Cam Fitzgerald

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Cam,

I believe that common spaces such as corridors, stairs, etc. should be
treated as residential when they are in buildings that fall under
residential building type as defined in the first note below Table G3.1.1A.
Also, based on Table G3.1#3 Space Use Classification, ? Usage shall be
specified using the building type or space type lighting classifications in
accordance with Section 9.5.1 or 9.6.1.? Table 9.5.1 has Multifamily
building type, which includes corridors, stairs, etc. (Note that G3.1.#3 is
otherwise not related to lighting.)

Another argument in favor of my interpretation is the example in 90.1 User
Manual for Sections 11 and Appendix G. It involves a mixed use building with
residential and non-residential floors (see screenshot below), and sets
System 1 (PTACs) as the baseline for residential floors, and System 5 (PVAV)
as the baseline for non-residential floors. If corridors on residential
floors were combined with non-residential floors below for the purpose of
determining baseline HVAC, we?d end up with more than 5 stories of
non-residential space, which would give us System 7 and not System 5.

Thanks,

Maria

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Hi Maria,
The predominant condition is determined only by conditioned area not gross
floor area.I feel the common spaces such as corridors,stairs etc should be
considered as residential or non-residential depending space type/floor it
serves.If these common spaces such as corridors,stairs etc are
unconditioned then no problem it doesn't affect the baseline system
selection.
Baseline System Selection:
If the conditioned area of both residential and non-residential space is
greater than 20,000sf then the project is eligible for G3.1.1 exceptions
a.Otherwise if either of the space type conditioned area is less than
20,000sf system selection is based on predominant conditioned area.

Cheers,
Dhayanandh

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I agree 100% with you Cam. I've modelled several 3 to 5-story barracks that not unlike dorms, have non-residential components to it that would fall under the exception. They would be modelled as another system baseline to compare only those spaces for energy efficiency. And yes, my first barracks that was reviewed got the inevitable "what is you second system type? You cannot model non-residential spaces as residential."

And, for everyone reading this...sometimes it's humbling to go back to the 90.1 definitions to understand what a conditioned, semi-conditioned, unconditioned space really means. Corridors with minimal exterior wall exposure may fall into "unconditioned space", which can be modelled as such in Trace700 by changing the Room to Unconditioned. This means that it will not be considered for unmet hours. It will be part of the lighting component. So which baseline do you assign corridors to? The non-residential system.

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

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