[BLDG-SIM] App G 2004 question

Bill Talbert btalbert at aeieng.com
Tue Apr 17 14:40:25 PDT 2007


Appendix G is the required method for demonstrating LEED energy credits
and the submittal requirements for EAC1 include energy end use for each
orientation. A90.1-2004 Addendum A modified Section G4.1.c to indicate
that the baseline building fenestration area should be equivalent to the
proposed (or 40% max) and 'shall be distributed on each face of the
building in the same proportion as on the Proposed Design.' The uniform
horizontal bands are no longer required which should help simplify the
process a little if USGBC/LEED is willing to adopt the addendum.
 
 
Bill Talbert, PE, LEED® AP
Mechanical Systems
Phone: (608) 441-6677
E-mail: btalbert at aeieng.com 

Affiliated Engineers Inc.
5802 Research Park Blvd.
Madison, WI. 53719
Tel. (608) 238-2616
Fax. (608) 238-2614

>>> "Leader, Philip" <Philip.Leader at akahn.com> 4/17/2007 3:01 PM >>>
The Appendix G is an informative appendix and is not part of Standard
90.1. It is merely informative and does not contain requirements
necessary for conformance to the Standard.
 
In the  Energy Cost Budget Method section in Table 11.3 under Section 5
Building Envelope, it describes the requirements for the Proposed
Building design and the Budget Building design.  The first paragraph
under the Budget Building design states.... The budget building shall
have identical conditioned floor area and identical exterior dimensions
and orientations as the proposed design, except as noted in (a), (b),
and (c) in this clause. 
 
There's nothing in the Standard stating you must rotate the building in
90 degree increments and average the results. We've never been asked to
do it to my knowledge by the USGBC during a LEED review of our
projects.
 
Philip S. Leader, PE 
Director of Mechanical Engineering 
Albert Kahn Associates, Inc. 
7430 Second Ave. 
Detroit, Michigan 48202-2798 
Phone: 313-202-7834 
FAX: 3130202-7334 
Email: philip.leader at akahn.com 
Website: www.albertkahn.com 

From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Brandon
Nichols
Sent: Tuesday, April 17, 2007 3:12 PM
To: BLDG-SIM at gard.com 
Cc: Shawn Gavras
Subject: [BLDG-SIM] App G 2004 question

All,
 
This is an old thread, but one I thought worth revisiting to see if
there have been any developments.  Specifically we are preparing a LEED
Silver project for submittal, and while we understand he intent of the
Appendix G 'multiple-orientation' and 'fenestration-leveling'
requirements, our evaluation is that they impose extensive calculation
requirements for arguably marginal returns on accuracy.
 
In the case of our specific building(as I would suspect the case of
90%+ of all buildings) there's simply no latitude to change the
orientation.  Similarly with glass distribution, the lobby and entryway
have the flexibility to be on one side and one side only of the
building, and thus distributing the glass equally amongst all facets for
the baseline model seems to add an unnecessary level of abstraction to
the comparative analyses.
 
Does imposing the requirement for analysts to spend considerable effort
developing fictitious baselines based on building orientations and glass
distributions that have 0% chance of construction seem to be a
reasonable requisite for LEED project certifications?  What I mean by
'considerable effort' is:
 
• That the all baseline numbers for each of the four orientations would
need to be extracted from the analysis software, averaged on a
spreadsheet, and a similar extraction done for all subsequent energy
efficiency measure (EEM) comparisons.  Posting these numbers from
analysis software to spreadsheets would be both time-consuming and
introduce another level of potential error, and thus require additional
error-checking.  
 
• That a new building would need to be developed, with glass
redistributed equally amongst all facets, for the four-point orientation
exercise described above.  Again, while this may sound reasonable from a
theoretical standpoint, practically speaking this requirement serves to
decouple the baseline from glazing-dependent energy efficiency measures.
 How meaningful is changing the U-value or shading coefficient of the
glass in an EEM in comparison to a fictitious baseline, when the glass
distribution is crucial to determining whether or not the measure is
cost-effective?  As with building orientations, posting these numbers
from analysis software to spreadsheets would be both time-consuming and
additionally error-prone. 
 
All to fulfill the requirement of deriving a fictitious baseline for
use in the comparative analyses -- no doubt these requirements were
incorporated with good intention, but practical implementation
considerations seem to have not been considered carefully enough.
 
Further, we find the concept of comparing proposed energy efficiency
measures to a "code minimum" baseline building, oriented identically and
glazed similarly to each of the EEMs, to be intuitively more meaningful
to both the owner and project team (and thus presumably to the LEED
reviewer) than comparison to a fictitious baseline.  This approach
allows the baseline to reside in the analysis software, and EEM
comparisons accomplished using the built-in 'parametric run' features of
the analysis software (eQuest and others) to reduce the time-consuming
error-prone tediousness of extracting and posting numbers to a
spreadsheet for comparative evaluation.
 
Has anyone had success in obtaining LEED project approval when
excepting these 'building orientation averaging' and 'glazing-area
leveling' requirements?  What is required in terms of the LEED
application to waive these requirements?
 
Also, does anyone know if these requirements have been identified for
relaxation or revision in the next LEED update?
 
 
Regards
 
Brandon Nichols, PE
Mechanical
HARGIS ENGINEERS
600 Stewart St
Suite 1000
Seattle, WA 98101
d | 206.436.0400 c | 206.228.8707
o | 206.448.3376 f | 206.448.4450
www.hargis.biz ( http://www.hargis.biz/ )
 
 
_________________________________________________
At 08:41 AM 1/24/2006, Bill Bahnfleth wrote:
 
Modeling the building in the specified orientations and averaging gives
an orientation-neutral baseline.

Appendix G has been developed with substantial input from experts at
PNNL and after discussions with USGBC. Glad to hear that modelers are
ignoring whatever they don't understand or find inconvenient.

Bill Bahnfleth
Member, ECB Subcommittee

At 09:42 PM 1/23/2006, Peter Alspach wrote:


A bit of a throw-back to the old 1989 version then? -----Original
Message----- From: Kevin Warren [mailto:kevin at warren-energy.com] Sent:
Monday, January 23, 2006 5:46 PM To: peter.alspach at arup.com;
bldg-sim at gard.com Subject: RE: [bldg-sim] App G 2004 question Peter,
I believe the intent is to give you a way to get some savings from
orienting your building with an eye toward savings. If you pay attention
to the sun in your design (passive solar and/or daylighting), you should
get some savings relative to the average of the rotated orientations.
Similarly, you could get a penalty if you have too much west-facing
glass. I'm not sure how strictly this provision is being enforced. Most
of the modelers I have spoken to ignore it, but that is a very
unscientific sample. These modelers may not be submitting to USGBC. For
a utility incentive program, it often does not make sense to do this
rotation. Those incentive programs typically care about the savings from
incremental changes to the design, particularly those changes that carry
an incremental cost. I'm not sure how one would determine an incremental
cost for your building's orientation, so it is not a factor that would
typically be eligible. Kevin Warren, P.E., CEM, LEED AP Warren Energy
Engineering, LLC (610) 255-3798 ph (610) 255-3406 f -----Original
Message----- From: bldg-sim at gard.com [mailto:bldg-sim at gard.com]On (
mailto:bldg-sim at gard.com%5DOn ) Behalf Of Peter Alspach Sent: Monday,
January 23, 2006 8:04 PM To: bldg-sim at gard.com Subject: [bldg-sim] App G
2004 question Anyone out there know the source of why one would be
required to simulate a building in an orientation that it is not in?
This doesn't really make any sense to me - am I missing something? Peter
-----Original Message----- From: bldg-sim at gard.com
[mailto:bldg-sim at gard.com] On Behalf Of Rohini Brahme Sent: Monday,
January 23, 2006 1:13 PM To: bldg-sim at gard.com Subject: [bldg-sim] App G
2004 question I have a question about the Appendix G in 90.1, 2004. In
Table G3.1 the baseline building is to be simulated as follows: "
Orientation. The baseline building performance shall be generated by
simulating the building with its actual orientation and again after
rotating the entire building 90, 180, 270 degrees, then averaging the
results. The building shall be modeled so that it does not shade
itself." What does --- the building shall be modeled so that it does not
shade itself ---- mean? Does it mean that if there is, for example, an L
shaped building (which self shades), it has to be modeled as square?
rectangle? Any thoughts on this appreciated. Thanks - Rohini
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_________________________________________________

William P. Bahnfleth, PhD, PE, Fellow ASHRAE

Professor of Architectural Engineering
Director, Indoor Environment Center

The Pennsylvania State University
104 Engineering Unit A
University Park, PA 16802 USA

voice: 814.863.2076 / fax: 814.863.4789
e-mail: wbahnfleth at psu.edu 
www.arche.psu.edu/faculty/WBahnfleth/ 
http://www.engr.psu.edu/ae/iec/ 
_________________________________________________


 

Brandon Nichols, PE

Mechanical
HARGIS ENGINEERS

600 Stewart Street
Suite 1000
Seattle, WA 98101
www.hargis.biz
 
d |206.436.0400  c | 206.228.8707
o |206.448.3376  f  | 206.448.4450
 

 
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