[Equest-users] External wall area for simulation

[Praveen Jain]

Thanks Nick for good explanation.

Actually in my project we are using almost 2ft wide external walls to get
the effect of thermal mass. if I consider external wall area in eQUEST model
my area deviation is almost 4% and mismatch in conditioned area is more than
this. So project energy consumption would be more and also not able to match
TR for the project.
Actually we are also planning to go for 2.5% renewable energy credit, if I
consider external wall than PV cost would be more.

Can I exclude external wall area for eQUEST modeling ?

--
With Thanks and Regards
Praveen

On Mon, Feb 28, 2011 at 10:02 PM, Nick Caton <ncaton at smithboucher.com>wrote:

>  Hi Praveen,
>
>
>
> I’ve copied below a discussion from some time back outlining my general
> practice for “where to draw the line” when it comes to envelope/wall
> boundaries.  This may be generally useful and seems to answer at least part
> of your inquiry.
>
>
>
> When I’m doing electrical and/or HVAC design alongside the model, my area
> takeoffs for each inevitably will match up, because I hate doing the same
> work twice.
>
>
>
> I use the outermost surfaces when defining my building footprint and
> midpoints for all internal partitions for all calcs.  Space-by-space LPD
> calcs in a strict reading do not require the space areas to be measured to
> the outermost surface of an exterior wall (they do say to use the midpoint
> of interior partitions, as of 90.1-2007).  I’d feel comfortable saying the
> extra square-footage “handicap” I’m imposing on myself as a lighting
> designer is an insignificant fraction in 99.9% of cases when determining
> baseline LPD…
>
>
>
> Inevitably, areas summed for all spaces in a building between architects,
> HVAC, and lighting designers will *not* match – that’s a fact of life and
> in my book that’s okay, so long as nobody is way off.  Model reviewers will
> inevitably/reliably gripe when the numbers don’t match exactly, and it’s
> usually  an easy thing to either fix or explain after the fact.  If you to
> try to make everyone use the same numbers from the DD/CD design phases,
> you’ve chosen a losing battle.  For my part in the role of the project’s
> energy modeler, I’m satisfied to allow my fellow designers do their own
> calcs, and just ensure nobody is way off along the way… quibbles over small
> differences in the final tallies, if they come up, are easy to reconcile.
>
>
>
> ~Nick
>
>
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, E.I.T.***
>
> PROJECT ENGINEER
>
> Smith & Boucher Engineers
>
> 25501 west valley parkway
>
> olathe ks 66061
>
> direct 913 344.0036
>
> fax 913 345.0617
>
> www.smithboucher.com* *
>
>
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Praveen Jain
> *Sent:* Monday, February 28, 2011 3:37 AM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] External wall area for simulation
>
>
>
> Dear All
>
>
>
> While modeling in eQUEST should we include external wall area or not?
>
> While creating single line diagram I exclude external wall and draw sld on
> inner of external wall to match conditioned area.
>
> But for lighting power density calculation ASHRAE 90.1 user manual suggest
> to including external wall area.
>
> We are getting mismatch in area calculation for all HVAC, Lighting and
> Architectural design sides.
>
>
>
> Can anyone suggest what correct way of modeling in eQUEST ?
>
> --
> With Thanks and Regards,
> Praveen K. Jain
> Roorkee
>
>
>
>
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Nick Caton
> *Sent:* Wednesday, August 04, 2010 1:20 PM
> *To:* John Aulbach; Nijenmanting, F.C.; equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] area of (internal) partitions
>
>
>
> Filique,
>
>
>
> This sounds a lot like a question I brought up when I was getting started
> with eQuest and energy modeling in general:  What is “standard practice”
> regarding where the inter-zonal and footprint boundaries are defined,
> relative to actual wall thicknesses?  The quick answer is that there aren’t
> any hard/fast answers to this.  It was a good discussion and is probably
> archived in [bldg-sim] if anyone cares to dig around…
>
>
>
> In short:
>
> 1.       eQuest areas correspond to the polygons used to define the floor
> areas/building footprint.  These polygons are defined by the shapes defined
> or traced from a CAD file in the wizards.  *I’m pretty sure* (someone
> correct me if I’m wrong) the floor area taken up by internal partitions
> (which have thickness) on the floor slab is NOT subtracted from the total
> area, so if you double the thickness of your internal partitions you will
> not see a change reflected in space areas.  This is normally not a big deal
> in the context of thermal modeled behavior, but if you have many unusually
> thick partitions (1ft or more deep), you might want to either account for
> them by modeling them as unconditioned zones between spaces.
>
> 2.       Regarding “best practice,” here’s a set of general guidelines
> that would apply to various loads & modeling software packages (beyond
> eQuest), prioritizing the interest of modeling with thermal accuracy:
>
> a.       Define interior partitions using the midpoint between the two
> surfaces.  This is generally not terribly critical – I will take small
> liberties on this to reduce the number of vertices and simply actual
> internal zones.
>
> b.      Define the building footprint areas using the outermost surface.
>   This is more important as you want to accurately model the actual amount
> of surface area subject to exterior loads.
>
> c.       Define top of each zone (in the z-axis) using the top surface
> elevation the respective floor or roof construction.
>
> 3.       On a related note, this ties into the general advice to not use
> energy modeling programs with the intent to create perfect 3D
> representations of your buildings.  If you need a pretty picture, they make
> 3D modeling software for that purpose.  When it comes to building
> geometries, simplicity is a virtue, and ASHRAE will even back you up on that
> one (re: 90.1 User’s Manual).  Avoiding overly-accurate building geometries
> lets you spend more time modeling the more critical building elements of a
> building’s energy behavior (loads/systems/schedules/etc).
>
>
>
> Best wishes,
>
>
>
> ~Nick**
>
> * *
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, E.I.T.***
>
> PROJECT ENGINEER
>
> 25501 west valley parkway
>
> olathe ks 66061
>
> direct 913 344.0036
>
> fax 913 345.0617
>
> *Check out our new web-site @ *www.smithboucher.com* *
>
>
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *John Aulbach
> *Sent:* Wednesday, August 04, 2010 12:15 PM
> *To:* Nijenmanting, F.C.; equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] area of (internal) partitions
>
>
>
> Filique:
>
>
>
> Can you rephrase your question, please?  I don't understand how doubling
> the size of your internal partitions decreases your floor area. The eQuest
> floor areas are (to my undestandinding), from the outside of outside walls
> to the "outside" of any internal partitions IN THE SPACE THAT PARTITION
> RESIDES. You can have only one internal wall separating two adjacent spaces.
>
>
>
> Others may comment.
>
>
>
> John R. Aulbach, PE, CEM
>
> Senior Energy Engineer
>  ------------------------------
>
> *Partner** **Energy***
>
> 1990 E. Grand Avenue, El Segundo, CA 90245
> W: 888-826-1216, X254| D: 310-765-7295 | F: 310-817-2745
>
> www.ptrenergy.com | jaulbach at ptrenergy.com <%7C%20jaulbach at ptrenergy.com>
>
>
>
>
>  ------------------------------
>
> *From:* "Nijenmanting, F.C." <F.C.Nijenmanting at student.tue.nl>
> *To:* "equest-users at lists.onebuilding.org" <
> equest-users at lists.onebuilding.org>
> *Sent:* Wed, August 4, 2010 12:15:19 AM
> *Subject:* [Equest-users] area of (internal) partitions
>
> Hello all,
>
> I have a question about the area which is calculated by equest.
> Does it take into account the width of internal partitions?
> In reality, if I would double the size of my internal walls, my actual
> floor area decreases.
> But I could not find differences in the floor area calculated by Equest if
> I change the thickness of my walls.
>
> A similar question accounts for the external partitions. For drawing the
> ground plan, should I therefore take the internal boundary, external
> boundary or middle line?
>
> Kind regards,
> Filique
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-- 
with regards,
Praveen K. Jain
Roorkee
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