[Equest-users] wwr calculation
JHANSEN at ghtltd.com
Wed Oct 19 13:56:49 PDT 2011
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...
James Hansen, P.E., LEED AP
1010 N. Glebe Road, Suite 200
Arlington, VA 22201-4749
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.
On Oct 19, 2011, at 12:20 PM, deepika khowal <deepika.khowal at gmail.com> wrote:
yes , i have been using LV-d report.
Am confused how it work for an unconditioned space.
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.
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?
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