[BLDG-SIM] Appendix G, Window wall ratio for the baseline

[David S Eldridge]

As far as the standard goes, I think the key point here is that the
baseline building evolves in the tables and sections from the proposed
building.  So once the proposed building changes, the baseline reacts.
Not the other way around.  

 

The real building to be built is where everything is derived from.
Prior incarnations of the design are no longer "proposed" - they have
been "eliminated".  Feel free to make quotation marks with your fingers
when you mention this.

 

So as far as a definition, how about Dictionary.com:
http://dictionary.reference.com/browse/proposed

 

1.to offer or suggest (a matter, subject, case, etc.) for consideration,
acceptance, or action: to propose a new method.

 

At this point in time you would be using antonym #1, "withdraw" to
describe the 40% WWR case.

 

Standard 90.1 doesn't cover withdrawn designs, only proposed ones.  No
energy code for paper projects, only the ones submitted to be
constructed (and subject to section 4.1 and 4.2 of course!)

 

David

 

 

 

 

 

 

From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Dana
Troy
Sent: Thursday, September 06, 2007 4:47 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Appendix G, Window wall ratio for the baseline

 

Hello All, 

 

 I have a question that pertains to ASHRAE 90.1-2004, Appendix G, Table
G3.1, No.5, which details modeling requirements for calculating proposed
and baseline building performance for the building envelope.  I'd
appreciate any thoughts you all might have on this LEED modeling.  

 

 We are currently working with a client on a building with a window-wall
ratio of 27%. The WWR was reduced from 40% by the architect in order to
obtain higher energy cost savings. When building the baseline model,
Appendix G states: 

 

 "Vertical fenestration areas for new building and additions shall equal
that in the proposed design or 40% of gross above-grade wall area, which
ever is smaller..." 

 

 Our client believes that since in the schematic design, the WWR was
over 40% and was then reduced to below 27% for energy efficiency
reasons, the baseline building should be modeled with a 40% WWR to show
these savings due to architectural design. 

 

 I understand that the proposed design stated in Appendix G refers to
the building that is going to be built, or the 100% CD drawings.
However, our client wants to see the definition of "proposed design"
from ASHRAE that explicitly states what the proposed design is. After
researching for a while, I found Addendum A, which states on page 4 of
the Addendum: 

 

 G3.1 Proposed Design Model. The simulation model o f   

 the proposed design shall be consistent with the design documents, 

 including proper accounting of fenestration and 

 opaque envelope types and areas; 

 

 and: 

 

 G3.6 Building Envelope. All components of the building 

 envelope in the proposed design shall be modeled as shown on 

 architectural drawings or as built for existing building envelopes. 

 

 This still is not enough to accurately define the proposed design. I am
sure that you might  all agree with me on the interpretation of Appendix
G, but does anyone know where I can find a solid definition of what the
proposed design is? I have searched the CIRs on the USGBC website and
came up empty handed and don't know where else to go. ASHRAE said a
formal interpretation request could take upwards of 6 months, so that is
also out of the question .  

 

 Any help would be greatly appreciated.  

 

 Thanks, 

 Dana Troy

 
 
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