[Bldg-sim] App G Wall boundary condition when abutting an adjacent building

[Nicholas Caton]

Hi Julien,



1.       Adiabatic makes sense if you can assert they’re similarly
conditioned structures

2.       I’d exclude such shared walls for the purposes of determining WWR

3.       If you frame the adjacent abutting properties as “existing
envelope conditions” precluding the design team from choosing any other
orientation, you might be able to cite CI #5224 as precedent to avoid the
rotation issues altogether:
http://in.usgbc.org/leed-interpretations?keys=5224+&=Search.  I might try
that first for preliminary submission, carefully citing that CI and
explaining the lack of rotations on the EAp2 template, within the 1.4
tables spreadsheet, and optionally within any supplemental narrative/report
you may include with preliminary submissions, if that’s your thing.



That explanation puts the issue on the table for the reviewer to agree with
or otherwise respond to.  In the event you are made to perform rotations
for final submission,  I wouldn’t “go nuts” or do anything special beyond
simply rotating the entire model unless given specific further direction by
the reviewer in preliminary review commentary.



On the other hand, maybe someone “in the know” will chime in on or off-list
for you ;)… it’s been known to happen!



Regards,



~Nick





*NICK CATON, P.E.*
*Owner*



*Caton Energy Consulting*
  1150 N. 192nd St., #4-202

  Shoreline, WA 98133
  office:  785.410.3317

www.catonenergy.com



*From:* Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] *On Behalf
Of *Julien Marrec
*Sent:* Tuesday, April 28, 2015 11:59 PM
*To:* bldg-sim at lists.onebuilding.org
*Subject:* [Bldg-sim] App G Wall boundary condition when abutting an
adjacent building



Hi,

Considering this is a software agnostic question, I thought I would ask it
to bldg-sim.

*I'm wondering how people have been treating the walls between the modeled
building and any adjacent, existing, buildings it's abutting in the
proposed design, when doing New Construction, especially with ASHRAE
Appendix G*

For EB and retrofit, there's no question, I'll treat it as adiabatic,
unless I have thorough reasons to believe the next door building is or will
be soon empty or even knocked down.

For New Construction, I'm a little bit more confused, especially
considering you're supposed to rotate your building for the baseline...

If I were to go crazy down that path: if I treat it as adiabatic, does this
mean I'd have to rotate the building manually, see what end ups in contact
with the adjacent building, and remove the windows there, while setting the
former adiabatic portion to exterior wall?

Here's an example of a project I'm working on right now (my building is 32
stories, the abutting are about 12 stories):

[image: My building is abutting three buildings]

*So what say you, fellow modelers?*

   - *Do you treat it as adiabatic? *
   - *If so, do you include that wall area in calculating the Window to
   Wall Ratio?*
   - *Do you rotate the building?*

*Do you have any sources for claiming one or another?* (ASHRAE
interpretation, LEED credit interpretation).



My personal two cents:

- I treat it as adiabatic

- Per Table G3.1.5a, "If it can be demonstrated to the satisfaction of the
Program Evaluator that the building orientation is dictated by site
considerations" ==> I don't rotate the building

- I don't include the adiabatic walls in the WWR calculation as I think the
intent was like this, though 90.1-2010 Table G3.1.5c (Baseline) does only
say: "...gross above-grade wall area" which could be interpreted otherwise.

Original question on Unmet hours is here
<https://unmethours.com/question/4709/wall-boundary-condition-when-abutting-an-adjacent-building>



Thanks for any insights,

Best,

Julien

--

Julien Marrec, EBCP, BPI MFBA
Energy&Sustainability Engineer
T: +33 6 95 14 42 13

LinkedIn (en) : www.linkedin.com/in/julienmarrec
LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr
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