[Equest-users] wwr calculation

[Robby Oylear]

Hi Pasha & Deepika,

Just trying to have a conversation here regarding your methods of modeling
parking garages.  Perhaps we can learn from one another in this exchange?

I find very little benefit to not including the parking garage in the model.
 You're increasing your project load and simulation run times by a marginal
amount, but you're gaining a more realistic model which accounts for the
temperature float of the unconditioned parking garage and the heat transfer
that will occur between it and the adjacent conditioned spaces.  Walls
between conditioned space and unconditioned space should not be modeled as
adiabatic, they should be modeled as Standard walls with a wall construction
per your architectural drawings.  These are also technically above grade
walls that should be included in your WWR calculation.

Going back to the original topic, WWR should be calculated based on the
gross area of exterior walls between conditioned spaces and
exterior/unconditioned spaces.  The LV-D report includes above-grade walls
that are adjacent to unconditioned spaces, so this incorrectly increases
gross above-grade wall area that should be used in your WWR calculation.
 Gross above-grade wall area should be calculated by the energy modeler or
architect based on the actual design drawings and then used to determine the
appropriate amount of glazing in the baseline model.  The LV-D reports can
be useful for calibrating the glazing in your model to the calculated
glazing area from the drawings.

Hope this helps,
-Robby

On Thu, Oct 20, 2011 at 8:56 AM, Pasha Korber-Gonzalez <
pasha.pkconsulting at gmail.com> wrote:

> Robby---
>
> No, I don't model adjacent walls as exposed unless they are exposed...you
> can detail adiabatic constructions if you want, don't you do this?
>
> Also--I agree that if there are conditioned spaces in commercial parking
> garages that are *included in the LEED project definition*, however if the
> parking garage is not included for LEED than I have the right to omit it
> from my model as I see fit (as the professional simulator of course.)
>
> Therefore, we are arguing professional judgements of opinion, where as this
> initial discussion uncovered that Deepika was referencing a commercial
> building model Energy Standard, where he should have been referencing a
> Residential Energy Standard.
>
> So why has this discussion turned so wildly away from the subject at
> hand?   I model my commercial garages correctly when they are required no
> matter what compliance program I am modeling for (i.e. LEED, Oregon ETO
> guidelines, Title-24, Savings by Design, etc.)
>
> My point about mechanical cooling is that if James is parking his car in a
> garage that has windows, doesn't the solar load into the garage space
> warrant that some amount of mechanical cooling is needed in his parking
> garage at work.  I can't imagine a sealed parking garage with windows not
> needing any mechanical cooling, otherwise I am sure that it would be like a
> Sauna when James leaves work at 6:00pm on the hottest day of the summer in
> the humidity-laden climate of Arlington, VA.
>
> My guess--and it is purely a guess, based on realistic assumptions and
> whole building science that his commercial/public parking garage at work has
> some sort of "open air" concept or extremely MASSIVE ventilation fans, to
> keep the conditions of the parking garage thermally acceptable AND
> ventilated so as not to "trap" all of the CO from the car exhausts that are
> entering and leaving the garage throughout the day.      If this is the
> case, or something similar, then it would not make his parking garage a very
> sustainable or energy efficient building due to the additional energy needed
> to manage the thermal temperatures inside and the toxic exhaust fumes that
> are now contained with in a parking garage that has windows.
>
> let's keep this discussion friendly and professional and not get too far
> off the original topic of discussion where the garage that Deepika was
> referring too was not a commercial parking garage---it is an attached garage
> to a private residence, in which he is not modeling for LEED for Commercial
> buildings and in which the WWR value of 40% does not apply to his project
> requirements.
>
>
> Pasha  :)
>
>
>
> On Thu, Oct 20, 2011 at 7:28 AM, Robby Oylear <robbyoylear at gmail.com>wrote:
>
>> I agree with James.  Modeling the garage is necessary to model the
>> associated conditioned spaces within that floor (heated storage rooms,
>> elevator lobbies, occupiable space adjacent to the garage).  Obviously the
>> garage is modeled as unconditioned, so I'm not sure what your point about
>> mechanical cooling is.
>>
>> When you exclude the parking garage from your model do you model all of
>> the adjacent spaces with exterior walls adjacent?
>>
>> -Robby
>>
>>
>> On Thu, Oct 20, 2011 at 5:03 AM, Pasha Korber-Gonzalez <
>> pasha.pkconsulting at gmail.com> wrote:
>>
>>> Do they provide mechanical cooling for your garage at work?   or does it
>>> have windows with no roof area....I'm sure your garage at work is not
>>> considered a "regularly occupied, fully conditioned (i.e. T-stat controlled)
>>> space".
>>>
>>> Pasha
>>>
>>>
>>> On Thu, Oct 20, 2011 at 4:51 AM, James Hansen <JHANSEN at ghtltd.com>wrote:
>>>
>>>> I model garages all the time.  I haven't done a building in a while that
>>>> didn't have some sort of conditioned space in the garages that needed an
>>>> adjacent unconditioned space (but without exterior walls) to properly
>>>> analyze.  Plus for LEED these days, they want all of your building areas in
>>>> the model to match those entered by the architect in the PI forms.  So you
>>>> are supposed to model garage elevator lobbies, semi-heated mechanical
>>>> spaces, main electric rooms, unheated garage space, etc.  ****
>>>>
>>>> ** **
>>>>
>>>> Also, my garage at work has windows :)****
>>>>
>>>> ** **
>>>>
>>>> -James****
>>>>
>>>> ** **
>>>>
>>>> *From:* Pasha Korber-Gonzalez [mailto:pasha.pkconsulting at gmail.com]
>>>> *Sent:* Thursday, October 20, 2011 6:33 AM
>>>> *To:* deepika khowal
>>>> *Cc:* James Hansen; equest-users at lists.onebuilding.org
>>>>
>>>> *Subject:* Re: [Equest-users] wwr calculation****
>>>>
>>>> ** **
>>>>
>>>> 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****
>>>>
>>>>  ****
>>>>
>>>> *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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>>>>
>>>> ** **
>>>>
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