[BLDG-SIM] WWR definition

[Michael Rosenberg]

Gerald, 

I am not sure I understand your question, but I will take a shot at answering. Appendix G is different from the body of the standard. Chapter 5 prescribes maximum fenestration areas as a % of gross wall area which includes below grade walls. Appendix G, in describing the hypothetical baseline building prescribes a maximum fenestration area as a percentage of above grade wall area. These two sections are clearly different.
 
Mike
 
Michael Rosenberg
Oregon Department of Energy
625 Marion St. N.E.
Salem, OR 97301-3742
Phone : (503) 373-7809
Fax: (503) 373-7806

>>> Gerald Pde 04/25/06 02:51PM >>> 
Michael, 
Appendix-g states that use 40% glazing if glazing % is 
above 40%, otherwise use whatever is smaller. From all 
the discussions regarding this above-grade/below-grade 
issue, we now learn that, as an update to the code, 
below grade walls(if the adjecent space is 
conditioned) are now included in the WWR calculations. 
Appendix-g should not change anything apart from the 
fact that glazing will need to be equally distributed 
through-out the above-grade facade, am I correct? 


Gerald 

--- Michael Rosenberg 
wrote: 

> Since many of you readers are using Appendix G of 
> Standard 90.1 for modeling LEED rated buildings you 
> should be aware that Table G.3.1.5 states in the 
> description of the baseline building for WWR; 
> 
> " Vertical fenestration areas for new buildings and 
> additions shall equal that in the proposed design or 
> 40% of gross above grade wall area, whichever is 
> smaller, and shall be distributed uniformly in 
> horizontal bands across the four orientations." 
> 
> As for the last part of that requirement, 
> distributing fenestration uniformly in horizontal 
> bands across the four orientations, that has been 
> removed in Addendum A to the 2004 Standard, but will 
> not be updated in the published version until 2007. 
> 
> Mike 
> 
> 
> 
> Michael Rosenberg 
> Oregon Department of Energy 
> 625 Marion St. N.E. 
> Salem, OR 97301-3742 
> Phone : (503) 373-7809 
> Fax: (503) 373-7806 
> 
> >>> "Larry Degelman" 04/24/06 
> 05:07PM >>> 
> Possibly the interpretation of what is gross wall 
> area depends on what 
> version of 90.1 you are looking at. As for 
> 90.1-2004, the official 
> interpretation on the ASHRAE web site leaves no 
> doubt that "gross wall area" 
> include both above- and below-ground walls. See the 
> following item verbatim 
> from the ASHRAE web site. 
> 
> 
> 
> INTERPRETATION IC 90.1-2004-1 OF ANSI/ASHRAE/IESNA 
> STANDARD 90.1-2004 
> 
> Energy Standard for Buildings Except Low-Rise 
> Residential Buildings 
> 
> 
> 
> 
> 
> Date Approved June 25, 2005 
> 
> 
> 
> Request from: Roger Chang (E-mail: 
> roger.chang at arup.com ), Associate Member, 
> 155 Avenue of the Americas, New York, NY 10013. 
> 
> 
> 
> Reference: This request for interpretation refers 
> to the requirements 
> presented in ANSI/ASHRAE/IESNA Standard 90.1-2004, 
> Section 5.2.1 Compliance, 
> relating to gross wall area. 
> 
> 
> 
> Background: Standard 90.1-2004 does not appear to be 
> clear as to what gross 
> wall area means. International Energy Conservation 
> Code is clear that 
> prescriptive requirements are based on window to 
> above-grade wall area. This 
> impacts all sections of the code where the 
> window-to- wall area ratio is 
> taken into consideration. 
> 
> 
> 
> 
> 
> Interpretation: Gross wall area refers to 
> above-grade wall only. 
> 
> 
> 
> 
> 
> Question: Is this interpretation correct? 
> 
> 
> 
> 
> 
> Answer: No. 
> 
> 
> 
> 
> 
> Comments: 
> 
> 
> 
> Section 3.2 defines "building envelope" to include 
> "the elements of a 
> building*that enclose...spaces through which thermal 
> energy may be 
> transferred to or from the exterior". 
> 
> 
> 
> Section 3.2, in the definition of "wall" states 
> "this includes above- and 
> below-grade walls, between floor spandrels, 
> peripheral edges of floors, and 
> foundation walls". 
> 
> 
> 
> Section 3.2 defines "gross wall area" as "the area 
> of the wall measured on 
> the exterior face from the top of the floor to the 
> bottom of the roof". 
> 
> 
> 
> Therefore, for buildings with conditioned space 
> below-grade, the gross wall 
> area extends from the top of the surface of the 
> floor of the lowest 
> conditioned space to the bottom of the roof of the 
> highest conditioned 
> space. 
> 
> 
> 
> (Note that the use of a similar term in a document 
> from another organization 
> is irrelevant to an interpretation of Standard 
> 90.1.) 
> 
> 
> 
> Page 1 of 1 
> �2005 ASHRAE. All Rights reserved. 
> 
> 
> 
> 
> 
> ===================================== 
> 
> Larry O. Degelman, P.E. 
> ldegelman at cox.net 
> 
> Prof. Emeritus of Architecture Ph./Fax: 
> 1-979-696-2506 
> 
> Texas A&M University 
> 
> ===================================== 
> 
> 
> 
> -----Original Message----- 
> From: BLDG-SIM at gard.com [ mailto:BLDG-SIM at gard.com] 
> On Behalf Of Jon McHugh 
> Sent: Sunday, April 23, 2006 8:40 PM 
> To: BLDG-SIM at gard.com 
> Subject: [BLDG-SIM] WWR definition 
> 
> 
> 
> Rene, Larry and Gerald, 
> 
> 
> 
> I think that the the underground wall area should be 
> included for each floor 
> that has windows. These windows in partially below 
> ground stories are 
> providing light and views that are no less important 
> than similar functions 
> provided on upper floors. However, if I have a 
> skyscraper with 4 stories of 
> underground garage of basement areas, I don't think 
> these fully underground 
> wall areas should be included. Rene, in evaluating 
> the energy and cost 
> impacts of windows in buildings, it is important to 
> look at the potential 
> for daylighting or the value of view, otherwise an 
> engineering analysis 
> might conclude that we don't need any windows at 
> all. 
> 
> 
> 
> Perhaps this should be brought up with the 90.1 
> envelope committee. 
> 
> 
> 
> Sincerely, 
> 
> 
> 
> Jon McHugh, PE, LC 
> Technical Director 
> Heschong Mahone Group Inc. 
> 11626 Fair Oaks Blvd #302 
> Fair Oaks, CA 95628 (Sacramento) 
> (916)962-7001 ext 38 
> (916)962-0101 FAX 
> e-mail: mchugh at h-m-g.com 
> URL: www.h-m-g.com 
> 
> 
> 
> _____ 
> 
> From: BLDG-SIM at GARD.COM [ mailto:BLDG-SIM at GARD.COM] 
> On Behalf Of Renee J. 
> Azerbegi 
> Sent: Sunday, April 23, 2006 11:11 AM 
> To: BLDG-SIM at GARD.COM 
> Subject: [BLDG-SIM] WWR definition 
> 
> It depends on the code in use. 
> 
> 
> 
> I submitted an official request (CM proposal) to the 
> ASHRAE 90.1 Envelope 
> committee to change the definition to only include 
> the above grade walls but 
> they declined it so it is still the above and below 
> grade walls. The reason 
> I sent the request is that architects tend to add 
> more glazing to the above 
> grade walls because they can include the below grade 
> walls in the 
> definition. I showed some modeling results of the 
> difference between a two 
> story building with one above and below grade wall 
> in a few difference 
> cities in the US and there was a significant energy 
> impact. 
> 
> 
> 
> However, I believe the IECC includes only the above 
> grade walls. 
> 
> 
> 
> Ren�e 
> 
> 
> 
> 
> 
> Ren�e Azerbegi, CEM, LEED-AP 
> 
> President/Sustainable Design Engineer 
> 
> ambient energy * solar & sustainable design 
> solutions 
> 
> t 303.278.1532 | f 303.278.8533 | c 303.885.2695 
> 
> renee at ambient-e.com 
> 
> ambient-e.com 
> 
> _____ 
> 
> From: BLDG-SIM at GARD.COM [ mailto:BLDG-SIM at GARD.COM] 
> On Behalf Of Larry 
> Degelman 
> Sent: Sunday, April 23, 2006 10:26 AM 
> To: BLDG-SIM at GARD.COM 
> Subject: [BLDG-SIM] 
> 
> 
> 
> Gerald et al, 
> 
> 
> 
> The conventional definition of window-wall-ratio is 
> the window area divided 
> by the "gross" wall area, though the term 
> "window-wall-ratio" is no longer 
> among the Definitions section of 90.1-2004. For 
> that matter, WWR is not 
> defined in the Abbreviations section. 
> 
> 
> 
> Notwithstanding all that, the definition for "Gross 
> Wall Area" is clearly 
> defined in the 90.1-2004 User's Manual. 
> 
> 
> 
> On page 5-30, example 5-G addresses "Determining 
> Gross Wall Area", stating 
> that this is very significant since the window area 
> requirements are based 
> on Window-Wall-Ratio (WWR). 
> 
> 
> 
> Answer (as shown on the same page): "The gross wall 
> area includes both 
> above-grade walls and below-grade walls so that 
> gross wall area is simply 
> the perimeter of the building * times the height*" 
> 
> 
> 
> Larry D. 
> 
> ===================================== 
> 
> Larry O. Degelman, P.E. 
> ldegelman at cox.net 
> 
> Prof. Emeritus of Architecture Ph./Fax: 
> 1-979-696-2506 
> 
> Texas A&M University 
> 
> ===================================== 
> 
> 
> 
> -----Original Message----- 
> 
> From: BLDG-SIM at gard.com 
> 
> To: BLDG-SIM at gard.com 
> 
> Sent: Fri Apr 21 09:06:56 2006 
> 
> Subject: [BLDG-SIM] ASHRAE 90.1 window-wall ratio 
> 
> 
> 
> I recently came across a paper from "Building Energy 
> 
> Codes Program" called "Setting the Standard" and 
> lists 
> 
> out various new code updates. It seems that 
> currently 
> 
> we are allowed to count below-grade walls as part of 
> 
> the window-wall ratio calculations. Does anyone 
> have 
> 
> an update on this or point me to the right resource 
> to 
> 
> confirm this information? 
> 
> 
> 
> Thanks. 
> 
> Gerald 
> 
> 
> 
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