[Bldg-sim] ASHRAE 90.1 Window to Wall area definition

Nicholas Caton ncaton at catonenergy.com
Fri Oct 16 13:50:34 PDT 2015


I agree, but can envision a few real-world cases where you might definitely
call the abutting walls part of the conditioned envelope, but would still
fall into the ballpark of “a grey area:”

·         What if the two abutting buildings aren’t sharing a wall, but
rather an enclosed unconditioned void/cavity?

·         What if you aren’t comfortable calling it an adiabatic surface
(i.e. the adjacent building is unconditioned/unoccupied)?



I think I’d fall back on a “gut check” in such instances:  If it makes zero
sense to install glazing for any proposed case design, then you should feel
safe consistently excluding those surfaces from the resultant WWR
requirements on the baseline side.  Put another way, don’t make the
baseline include windows where it’s completely unreasonable (this also
encompasses my “facing dirt” litmus test).



I know that isn’t terribly black & white – I wouldn’t be surprised if some
specific urban energy codes have tread these paths enough to address the
various possibilities for abutting buildings… (?)



~Nick



*NICK CATON, P.E.*
*Owner*



*Caton Energy Consulting*
  306 N Ferrel

  Olathe, KS  66061

  office:  785.410.3317

www.catonenergy.com



*From:* Elizabeth Gillmor [mailto:elizabeth at energetics-eng.com]
*Sent:* Friday, October 16, 2015 3:32 PM
*To:* Julien Marrec
*Cc:* Nicholas Caton; Jones, Christopher; bldg-sim at lists.onebuilding.org
*Subject:* Re: [Bldg-sim] ASHRAE 90.1 Window to Wall area definition



Another interesting question!



If you look at how ASHRAE 90.1 defines "exterior building envelope", as
being "the elements of a building that separate conditioned space from the
exterior space", then I would say that no, your adiabatic walls do NOT
contribute to your building envelope or your WWR, because they do not abut
exterior space.  So you should exclude them from your calc.


*Elizabeth Gillmor  **PE, BEMP, LC, LEED AP*



*e n e r g e t i c s  **consulting engineers, llc*

energetics-eng.com

c 303.619.0091



On Fri, Oct 16, 2015 at 1:50 PM, Julien Marrec <julien.marrec at gmail.com>
wrote:

This discussion is very interesting and  relates to another question I
asked before, and since it didn't get much traction and this one did,
please allow me to bring it up again.



For above grade walls that are abutting an existing building (adiabatic),
do you include those in the WWR calculation or exclude them?



Thanks,

Julien

Envoyé de mon iPhone


Le 16 oct. 2015 à 04:38, Nicholas Caton <ncaton at catonenergy.com> a écrit :

Whether you choose to build your baseline before/during/after your proposed
case, you will need to very actively reference the proposed/actual design
along the way to determine where the conditioned spaces lie (per the
glossary entries), and from there where the envelope line is drawn
separating the conditioned from the exterior/unconditioned/semi-conditioned
areas.



Insofar as the WWR discussion thread goes, I believe I’m situated in
Nathan’s camp.  I simply (?) equate/read “above-ground” in Appendix G to
mean “not facing dirt,” regardless of where the grade lies.



~Nick



*NICK CATON, P.E.*
*Owner*



*Caton Energy Consulting*
  306 N Ferrel

  Olathe, KS  66061

  office:  785.410.3317

www.catonenergy.com



-----Original Message-----
From: Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of
Duggin, Cory
Sent: Thursday, October 15, 2015 1:59 PM
To: Jones, Christopher
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] ASHRAE 90.1 Window to Wall area definition



According to my understanding it would be based off the proposed.





*From:* Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] *On Behalf
Of *Jones, Christopher
*Sent:* Thursday, October 15, 2015 1:56 PM
*To:* 'Elizabeth Gillmor'
*Cc:* bldg-sim at lists.onebuilding.org
*Subject:* Re: [Bldg-sim] ASHRAE 90.1 Window to Wall area definition



Thanks Elizabeth,

Your reply brings up another question.  If the proposed design meets the
requirement of Table 3.1 does the baseline automatically follow suit?  Or
does one have to first construct the baseline case model to determine the
self-sized heating capacity to determine if the space is conditioned or
semi-heated?  It sounds like it would be an iterative process – first model
the space with exterior insulation for a conditioned space then determine
the heating capacity.  If it shows a semi-heated space, then change the
insulation and check again, and so on?





<image001.png>

*Christopher Jones,* P.Eng.
Senior Engineer



*WSP Canada Inc.*

2300 Yonge Street, Suite 2300

Toronto, ON M4P 1E4
T +1 416-644-4226

F +1 416-487-9766

C +1 416-697-0056



www.wspgroup.com



*From:* Elizabeth Gillmor [mailto:elizabeth at energetics-eng.com
<elizabeth at energetics-eng.com>]
*Sent:* Thursday, October 15, 2015 2:36 PM
*To:* Jones, Christopher
*Cc:* bldg-sim at lists.onebuilding.org
*Subject:* Re: [Bldg-sim] ASHRAE 90.1 Window to Wall area definition



It would have to be heated enough to qualify per Table 3.1, which would be
pretty high:



<image002.png>



And then you would have to insulate it like a conditioned space (rather
than just a semi-heated space).  But yes, then you could count it!


*Elizabeth Gillmor  **PE, BEMP, LC, LEED AP*



*e n e r g e t i c s  **consulting engineers, llc*

energetics-eng.com

c 303.619.0091



On Thu, Oct 15, 2015 at 12:24 PM, Jones, Christopher <
Christopher.r.Jones at wspgroup.com> wrote:

So up here in Zone 6 and 7 where the first level of parking below grade is
often heated enough to make it a conditioned space, one would count those
below grade walls in the WWR for the Energy Cost Budget method.  That can
make a somewhat significant difference in how much glazing the baseline
case has in the above grade walls.





<image001.png>

*Christopher Jones,* P.Eng.
Senior Engineer



*WSP Canada Inc.*

2300 Yonge Street, Suite 2300

Toronto, ON M4P 1E4
T +1 416-644-4226

F +1 416-487-9766

C +1 416-697-0056



www.wspgroup.com



*From:* Elizabeth Gillmor [mailto:elizabeth at energetics-eng.com]
*Sent:* Thursday, October 15, 2015 2:07 PM
*To:* Shaun Martin
*Cc:* Jones, Christopher; bldg-sim at lists.onebuilding.org
*Subject:* Re: [Bldg-sim] ASHRAE 90.1 Window to Wall area definition



That is a great point. Appendix G is different from the prescriptive
requirements.



The prescriptive requirements (and thus Energy Cost Budget method) allow
you to count below-grade conditioned walls as per section 5.5.4.5 as part
of your "gross wall area", while Appendix G specifically says above-grade
walls only.




*Elizabeth Gillmor  **PE, BEMP, LC, LEED AP*



*e n e r g e t i c s  **consulting engineers, llc*

energetics-eng.com

c 303.619.0091



On Thu, Oct 15, 2015 at 11:38 AM, Shaun Martin <
smartin at shaunmartinconsulting.com> wrote:

Page 213 of 90.1-2010 says “above-grade”



Shaun



Shaun Martin LEED-AP, BEMP

Principal

Shaun Martin Consulting

#90 – 425 Carrall Street

Vancouver, BC  V6B 6E3

p. 604-789-1095







*From:* Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] *On Behalf
Of *Jones, Christopher
*Sent:* Thursday, October 15, 2015 10:15 AM
*To:* bldg-sim at lists.onebuilding.org
*Subject:* [Bldg-sim] ASHRAE 90.1 Window to Wall area definition



I know this question has been asked before but I could not find a related
thread.



90.1 states that the WWR is based on the gross wall area and the definition
of gross wall area includes below ground walls as well as above ground
walls..  Including the below grade walls can make a significant difference
in the WWR for typical urban high rise buildings with a number of below
grade parking floors.



Can someone confirm that the WWR calculation is based on above grade wall
area plus below grade wall area?





<image001.png>

*Christopher Jones,* P.Eng.
Senior Engineer



*WSP Canada Inc.*

2300 Yonge Street, Suite 2300

Toronto, ON M4P 1E4
T +1 416-644-4226

F +1 416-487-9766

C +1 416-697-0056



www.wspgroup.com


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