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

Julien Marrec julien.marrec at gmail.com
Tue Apr 28 23:59:12 PDT 2015


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

Thanks for any insights,



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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