[Equest-users] [Bldg-sim] FW: Wall classification for adjacentbuildings

Tue Sep 6 08:17:41 PDT 2011

I'm sure local standards and code application/enforcement varies widely
around the world, but in my general practice I do not design systems
anticipating other portions of the building completely going away...
FEMA/disaster shelters being a common exception =)...  

Unless demolition of the adjacent building is a definite and planned
venture in the near future, I would not deliberately oversize systems
for such reasons.  Oversized systems can introduce a host of ongoing
issues for the building owner/occupants involving comfort, budget and
operating efficiency, and for as long as the adjacent building is
standing such a system in operation is simply incorrectly sized for the
application.  

If demolition or destruction is a certain/likely possibility in the near
future, I might define and incorporate means by which an auxiliary MEP
systems (as appropriate) could be easily added if/when that occurs to
take on the additional loads for the affected zones.  I would
simultaneously advise treating the envelope's construction as though it
were exterior so far as its construction is concerned, though that is
more out of common-sense than any code/standard-driven requirement.

In any case, I would be surprised to find an energy code-compliance
official requiring abutting, structurally independent walls as you've
described them to be counted as exterior surface area.  Conversely I
would not as a designer include such areas in trying to "squeak by" for
lighting, WWR or similar calculations.

That's my opinion anyway, for what it's worth!  Best to leave any
specific code application/enforcement questions to your local AHJ as
they'll have the final say regardless of anyone's feelings here on the
lists.

~Nick

NICK CATON, P.E.

SENIOR ENGINEER

Smith & Boucher Engineers

25501 west valley parkway, suite 200

olathe, ks 66061

direct 913.344.0036

fax 913.345.0617

www.smithboucher.com 

From: Mirza Sajjal [mailto:Mirza.Sajjal at BuroHappold.com] 
Sent: Tuesday, September 06, 2011 9:44 AM
To: Nick Caton; bldg-sim at lists.onebuilding.org;
equest-users at lists.onebuilding.org
Subject: RE: [Bldg-sim] FW: [Equest-users] Wall classification for
adjacentbuildings

Thanks for the quick response Nick. 

Do you also have an opinion on the code issue, will it have to be
compared to exterior walls or interior walls if the walls aren't really
"shared" but are adjacent to each other with no exposure to the
environment? What if the adjacent building is demolished, shouldn't the
HVAC system be sized to meet that condition (or the wall built up to
exterior wall performance values)? I'm curious to understand how this is
approached in an MEP/code compliance standpoint.

Thanks again for the feedback.

Mirza

From: Nick Caton [mailto:ncaton at smithboucher.com] 
Sent: Tuesday, September 06, 2011 10:18 AM
To: Mirza Sajjal; bldg-sim at lists.onebuilding.org
Subject: RE: [Bldg-sim] FW: [Equest-users] Wall classification for
adjacentbuildings

Hi Mirza,

In my experience, "shared walls" are not counted as "exterior surface
area" for any WWR calculations or similar.  

In eQuest/DOE2 terminology:  "Interior walls" model heat transfer (or
lack thereof, in the case of an adiabatic wall) between two spaces.
They will not interact directly with exterior conditions.

Surfaces separating building spaces from outside ambient conditions are
"exterior" surfaces. 

There are no hard rules as to how you "should" model a shared wall, but
in eQuest you have at least a few options I think anyone would agree are
acceptable in most cases:

-          Assuming heat transfer between the associated conditioned
spaces is negligible, but assuming the thermal mass of said wall is
important for accuracy, model an adiabatic wall (default approach coming
out of the wizards in eQuest).

-          Assuming heat transfer between the associated conditioned
spaces is negligible, and the thermal lag caused by the mass is also
negligible for accuracy, simply delete any such walls and don't model
them at all.

-          Assuming heat transfer is important for the model's accuracy,
model a normal interior partition and also expand your model to include
the adjacent building space and its envelope, internals and systems.

If somebody demolishes half of your building in the indeterminate
future, I think we'd all agree that would probably warrant an update to
the model and you'd treat the surfaces newly exposed to the exterior as
such.

~Nick

NICK CATON, P.E.

SENIOR ENGINEER

Smith & Boucher Engineers

25501 west valley parkway, suite 200

olathe, ks 66061

direct 913.344.0036

fax 913.345.0617

www.smithboucher.com 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Mirza
Sajjal
Sent: Tuesday, September 06, 2011 8:52 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] FW: [Equest-users] Wall classification for
adjacentbuildings

Thought I'd send this out to the bldg-sim list as well.

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Mirza
Sajjal
Sent: Friday, September 02, 2011 12:50 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Wall classification for adjacent buildings

Hi All,

I was wondering if anyone has an idea on an issue that I've come across
regarding what is considered an exterior wall and whether the wall area
should be included in the window-wall ratio calculations. 

There are two existing buildings which have walls touching with no air
gap, but if one of the buildings were to be demolished the other will
not be affected i.e. structurally independent (although there is very
little possibility the building will be demolished). My question is
whether these walls are considered exterior or interior walls? My
understanding is that the energy model should simulate it as an
adiabatic wall but it should be considered an exterior wall for code
compliance and window-wall ratio calculations.

Any feedback is much appreciated. Thanks in advance.

Regards,

Mirza

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