[Equest-users] 2015 NECB Question, Intersecting Floor and Wall Area

[Calvin Chu]

Hi Chris,

Not a Canadian but this situation sounds very similar to what I also
frequently encounter when I have to model above-grade wall floor edges for
the baseline and proposed models. I couldn't find any mention of how to
model the baseline floor edges in ASHRAE 90.1-2016. For the baseline model
floor edges, I typically use the baseline above-grade wall
constructions/U-values for the floor edges and model the proposed floor
edges without any insulation as you have done. You can also try looking at
Energy Star's Multifamily High Rise Simulation Guidelines Version 1.0,
December 2017 Example 6-2, which supports your idea of modeling your
proposed floor edges without any insulation.

Kind regards,
Calvin

On Thu, Apr 25, 2019 at 12:02 PM Chris Hadlock via Equest-users <
equest-users at lists.onebuilding.org> wrote:

> Good morning,
>
> For you Canadians, I have a question about how to model the area where a
> floor slab intersects the exterior wall.
>
> Specifically, Section 3.1.1.7.8) of the 2015 NECB says that "wall
> assemblies shall be considered to include all related structural framing
> and perimeter areas of intersecting interior walls *but shall not include
> the perimeter areas where floor or roof slabs interrupt the wall's
> construction." *
>
> There is a reference to Note A-3.1.1.7.(8) which provides an illustration
> to depict the extent of the surface that is considered as a wall at the
> intersection with a floor. In this note, it also says "This Code may have
> different requirements for the perimeter area of floors."
>
> Since I haven't seen any such requirements (how anyone else), I'm not sure
> how to treat this area.
>
> When I have a building in which the insulating layer in the exterior wall
> assembly is intersected by the floor slab (thus breaking the insulation
> plane), I typically model my Proposed building with a separate assembly for
> the slab edge and assign a low R-value (reflective of a wall with no
> insulation).
>
> My question then is, in this case, what would people model for the
> Reference model in terms of R-value at the slab edge (where the floor
> intersects the wall)?
>
> As mentioned, I have not seen anything in NECB that specifically deals
> with the treatment of the slab edge (other than at grade level). Would the
> Reference model carry the same R-value as the Proposed model?
>
> Thank you in advance for your input and thoughts.
>
> Chris
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-- 
*Calvin Chu, EIT*
Energy Modeler
646-780-5536 | cchu at brightpower.com
www.brightpower.com
<http://www.brightpower.com/?utm_source=email&utm_medium=signature>
11 Hanover Square, 21st Floor
New York, NY 10005
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