[Equest-users] wwr calculation

[Nick Caton]

Hmm*...  

 

I think my experience and present thinking sandwiches me somewhere in
the middle of these proposed approaches/assertations...  Aboveground
parking garages in my models are never "excluded" entirely, but like
Pasha typically manifest as a collection of building shades, external
lighting loads and process fan loads to represent mechanical
ventilation.  Ventilation/lighting loads are defined with unique
scheduling to capture their controls at the meter or sub-meters for easy
documentation/model verification.  Building walls against the garage are
modeled as exterior surfaces, shaded but otherwise exposed to outside
ambient conditions

 

Modeling an unconditioned garage as an unconditioned space/zone (in
eQuest terms) is something I did starting out, and if the garage is very
large/enclosed may allow for a better representation of temperatures for
"semi-conditioned partitions," but it just seems like more work to me
altogether, particularly in LEED documentation and reviewer
clarifications like those bringing this discussion up... 

 

I personally model conditioned and semi-conditioned garage spaces (like
elevator lobbies) as eQuest spaces/zones exactly where they are located
- within the garage or along the actual building perimeter.  To one of
James' & Robby's points, these are modeled with exterior walls and in
spite of the garage building shades may experience more extreme
temperatures than in reality as the tempering effects of big slabs of
concrete are present even in fully open garages.  For the context of
LEED:  the baseline/proposed remain on level footing however by 90.1's
design, and I've yet to run into the case where such "more extreme"
conditions resulted in unmet hours, forcing a more accurate
representation.

 

Suffice to say, I believe there's more than one "right" way to model a
garage, with different approaches having unique qualities considering
degree-of-accuracy & time-efficiency.  We should remember an
"appropriate" degree of accuracy for one model may be overkill for
another (time better spent improving the accuracy of something else).
In energy modeling it's normally difficult to generalize and say any
single approach is "right."

 

WWR with my approach remains a calculation using the gross exterior wall
& fenestration areas of the non-garage building.  The exterior surfaces
of the garage (conveniently) don't wedge their way into eQuest's outputs
to be removed later, because they are not modeled as space surfaces.
Note the alternative of including the garage surfaces for WWR calcs
could ultimately either help OR hurt your performance rating - not sure
if everyone is picking up on that.  It would appear both interpretations
have made it through the LEED reviewer gauntlet in any case.

 

To an earlier point/query somebody touched on: "Enforcement" of
not-quite-matching areas for LEED is something I find to reflect a
reviewers general familiarity (or not) with building modeling practice.
If it's noted my models' totals are very different because they don't
include the gross area of a garage and someone else filled out their
LEED templates in a different fashion, I explain/reiterate the garage is
in fact modeled, the difference in areas are appropriate/expected and
merely the result of how areas are tallied for spaces within eQuest.  If
a reviewer should thereafter insist the areas match exactly, an
obstinate response would cost our project team money due to an
additional review, or has otherwise annoyed me to the point I don't feel
like educating him/her, I might just add a dummy space of the
appropriate area to make the tallies match.  I haven't run into that
particular reviewer just yet though =).

 

I cannot speak to modeling fully conditioned (heated and cooled) parking
garages, but if I that crossed my desk I would intuitively define a
conditioned space - I think that places fully conditioned garages out of
the current discussion.

 

~Nick

 

*  I observe multiple individuals oversimplifying/re-interpreting valid
points others are trying to share... take note that's not furthering the
discussion and only making you look quarrelsome...

 

 

 

 

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: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of deepika
khowal
Sent: Thursday, October 20, 2011 12:57 PM
To: Pasha Korber-Gonzalez
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] wwr calculation

 

I never mentioned am using 90.1 standard.

it was a generic question about calculating wwr .

and if you say its not important to model unconditioned spaces, how do
you account for heat transfer between conditioned and unconditioned
spaces?

 

Thanks

Deepika

On Thu, Oct 20, 2011 at 3:33 AM, Pasha Korber-Gonzalez <
pasha.pkconsulting at gmail.com> wrote:

I disagree with both of you.

First of all, who models Garages in their models anyway?  What a waste
of time.---this scews the gross floor area, and nothing in a parking
garage impacts the HVAC equipment loads of the conditioned spaces....you
can always input your garage vent fans and lighting as single exterior
load input numbers in your model which simplifies the whole modeling
project and billable time spent WITHOUT compromising on the calculations
of energy use....

Second of all---poor example for offering windows in a parking
garage--this is never real life, and a non-applicable example doesn't
"hold water".   At least give an example that is comparable to real life
situations...  Parking garages are either open air, or underground
(without fenestration...)   Have you ever had a project where Mechanical
cooling needed to be provided to a parking garage?  I hope not because
these are considered transient space types.

If you are modeling your LEED buildings according to appendix G --90.1
you do not include the above grade garage wall area in your gross
building WWR calculation.

FOURTH---Deepika---you are modeling a residential home from your picture
you sent us.   YOU CANNOT USE ASHRAE STANDARD 90.1 TO MODEL LOW-RISE
RESIDENTIAL BUILDINGS!

You are using and interpreting the wrong standard, you need to use
ASHRAE Standard 90.2 for Non-commerical Residential buildings.    You
will need to use this new reference as everything you are referring to
does not apply for your project or your project model.
 
The real answer to your question is the Nebraska Cornhusker football
team IS BETTER than the Virgina Tech Hoakies!     GO BIG RED!!!!
Pasha

 

On Wed, Oct 19, 2011 at 3:15 PM, deepika khowal <
deepika.khowal at gmail.com> wrote:

I agree with James .

if its unconditioned space, we should not claim the window area . that
way we can have higher WWR for rest of conditioned spaces.

 

 

On Wed, Oct 19, 2011 at 1:56 PM, James Hansen <JHANSEN at ghtltd.com>
wrote:

I don't think I agree with this advice

 

Under ASHRAE 90.1-2007, Section 5.2.1, part of the requirements for the
PRESCRIPTIVE method requires that "the vertical fenestration area does
not exceed 40% of the gross wall area for each space-conditioning
category". 

 

The definition for "space conditioning category" simply says:

 

                non-residential conditioned space,

                residential conditioned space, and

                nonresidential and residential semiheated space

 

It doesn't list unconditioned space.  Now I know this info is listed in
the prescriptive requirements, but if it was my model, and I had a
garage that had 100% window area, there is no way I would count that
towards the gross WWR, particularly if I was applying for LEED, and
these inconsequential windows pushed my WWR above 40% and thus penalized
my proposed building.  In fact, I might not even model the windows,
unless I felt they were going to superheat the garage and start
impacting adjacent space cooling loads.

 

Just my opinion...

 

GHT Limited
James Hansen, P.E., LEED AP
Senior Associate
1010 N. Glebe Road, Suite 200
Arlington, VA  22201-4749
703-243-1200 (office)

703-338-5754 (cell)
703-276-1376 (fax)

www.ghtltd.com <http://www.ghtltd.com/> 

 

From: equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] On Behalf Of PKConsulting
Sent: Wednesday, October 19, 2011 4:04 PM
To: deepika khowal
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] wwr calculation

 

It doesn't change for unconditioned or conditioned.  It is only a
function of gross wall area (ft2) and window area (ft2).   Don't think
too hard about this.  You are looking for a needle in the wrong
haystack.   This one is straight forward with no tricks...

 

WWR is for whole bldg not space by space.


Pashalu


On Oct 19, 2011, at 12:20 PM, deepika khowal <deepika.khowal at gmail.com>
wrote:

	Thanks Pasha

	 

	yes , i have been using LV-d report.

	 

	Am confused how it work for an unconditioned space.

	Thanks

	On Wed, Oct 19, 2011 at 11:01 AM, PKConsulting <
pasha.pkconsulting at gmail.com> wrote:

	It should be the gross wall area for everything above ground.
Use the lv-d report to find the numbers to calculate the overall WWR for
your entire bldg.   There is a summary page at the end of the lv-d
report.  Look for the line called-'all walls'.  You can use those
numbers to calc WWR percentage.
	
	Pashalu

	
	On Oct 19, 2011, at 11:39 AM, deepika khowal <
deepika.khowal at gmail.com> wrote:
	
	> Hi all
	>
	> I have a question about calculating WWR.
	> for example, if the south wall area is 700sf and total window
area is 70sf then the WWR should be 10%.
	> but if 50% of south wall is part of a garage and is
unconditioned, then in calculating WWR , should I include only the wall
area for conditioned space or it should include complete facade?
	> Thanks
	>
	> Deepika
	>
	>
	>
	>

	> <image.png>
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