[Equest-users] Fenestration and Window to Wall Ratio

[Dana Troy]

90.1 Appendix G states: "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."

 

If you are using 90.1 as your State's code, then you can include the below-grade wall area. If you are modeling using Appendix G, then you cannot include the below grade wall area in your calculations.

 

-Dana

 

 

Dana Troy

Senior Energy Analyst

GLUMAC | 503.227.5280

 

 

 

 

-----Original Message-----
From: James Newman [mailto:James.Newman at me-engineers.com] 
Sent: Tuesday, February 08, 2011 3:29 PM
To: Sunayana Jain
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Fenestration and Window to Wall Ratio

 

This paragraph comes directly out of the ASHRAE 90.1-2007 User Manual:

 

"Window-Wall Ratio: The window-wall ratio is the ratio of vertical fenestration area to gross exterior wall area. The fenestration area is the rough opening, i.e., it includes the frame, sash, and other nonglazed window components.  The gross exterior wall is measured horizontally from the exterior surface; it is measured vertically from the top of the floor to the bottom of the roof. The gross exterior wall area includes below-grade as well as above-grade walls. It is necessary to calculate the window-wall ratio with all compliance options, since this information is need with the prescriptive option, the trade-off option, and the energy cost budget method."

 

James M. Newman, EIT, LEED AP

project engineer / energy analyst

 

 

-----Original Message-----

From: Sunayana Jain [mailto:sunayana_jain at neo.tamu.edu] 

Sent: Tuesday, February 08, 2011 4:20 PM

To: James Newman

Cc: equest-users at lists.onebuilding.org

Subject: Re: [Equest-users] Fenestration and Window to Wall Ratio

 

Hi James,

 

As per my understanding, window wall ratio is considered for above grade walls only for each orientation of building (not floor to floor).

 

Thanks,

 

Sunayana Jain

 

LEED AP, EIT

 

Energy Engineering Specialist

 

----- Original Message -----

From: "James Newman" <James.Newman at me-engineers.com>

To: equest-users at lists.onebuilding.org

Sent: Tuesday, February 8, 2011 5:29:50 PM GMT -05:00 US/Canada Eastern

Subject: [Equest-users] Fenestration and Window to Wall Ratio

 

 

 

 

 

When calculating the window to wall ratio for your baseline building, should you calculate this percentage as 

 

  

 

·          an entire building? 

 

·          each building elevation? 

 

·          every floor elevation? 

 

  

 

Has anyone had an interpretation on this issue?  I was reading through the 90.1 User manual and discovered that both above grade walls and below grade walls should be considered for the wall to wall ratio which leads me to believe the calculation should be done as a whole building percentage. Just curious if someone knows the correct answer. 

 

  

 

Thanks, 

 

  

 

James M. Newman, EIT, LEED AP 

 

project engineer / energy analyst 

 

  

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