[Equest-users] Roof for multi-story building

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I have a two story building. The second floor has a smaller foot-print than the first floor. I placed the second floor immediately above the first floor in the wizard. What I am noticing is, for the first floor, equest is creating an exterior roof for the entire 1st floor foot-print although areas where portions of the first floor covered by second floor will not have an exterior roof. For the 1st floor, will e-quest calculate the heat-loss/gain for the entire area of the roof or will it know that there is a floor above and will discount for the area of the second floor. If not, how do you deal with this. FYI: I don't have identical zone for the first and second floor.

One other thing I did is, I tried to validate it by creating two story building by using shell multiplier in wizard and noticed equest is not creating an exterior roof for the 1st floor.
Regards,
Yuvaraj

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Joined: 2011-09-30
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A generic reminder: The mailing list archives are a resource every
modeler should bookmark and utilize - many times the unique questions
that come up as you're learning have already been asked and answered!
You can find the links for the bldg-sim and equest-users search pages,
among other useful tidbits, here: http://onebuilding.org/wiki/doku.php

"Sandwiched" roof surfaces between two shells WILL interact with the
exterior conditions. If you have multiple shells with partially
exposed roofs coming from the wizards, you can handle the situation many
ways within detailed mode. Here are a few suggestions for varying
effort/accuracy:

* Low effort: Delete all roof surfaces which are fully
"sandwiched" by the two shells

* Moderate effort: Delete roof surfaces which are fully
"sandwiched" by the two shells, then modify those which are partially
covered to be an appropriate surface area.

* Medium-High effort: Do the above, but also move/reshape the
modified surfaces to ensure they receive direct solar loads but are
shaded by other parts of the model as appropriate.

* "I have no time to waste on accuracy": Approximate the
building as one multi-story shell using an identical averaged footprint
for each floor.

The first option is what I'd call "good enough" for many cases. The
model creator gets to make the ultimate judgement regarding what's
appropriate however when it comes to accuracy.

That last option is generally appropriate when you need a quick
estimate/answer, but not what I'd personally call a "finished product"
outside of specific cases in SD-level modeling.

Your "validation" investigation is something I'd encourage and often do
myself when I want to get a question answered - sometimes the
best/quickest way to figure something out is to construct and run a
test/experiment.

That said, I think you may be misled a bit: True - there are no
ceilings generated for multistory plenums by the wizards... Where that
might lead you to believe heat transfer isn't being modeled between
floors (a fair assumption for many multistory buildings, btw), "one
man's floor is another man's plenum ceiling." Note the floors for 2nd+
story spaces are interior surfaces thermally tied to the corresponding
plenum below ;).

Armed with that bit of knowledge:

* Highest effort: Do the above steps, then also create/modify
the 2nd+ story floor surfaces as standard interior surfaces with
associations (thermal ties) to the appropriate ceiling plenums below,
just as the wizards do for a multi-story shell.

~Nick

NICK CATON, P.E.

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