[BLDG-SIM] App G 2004 question

Charles Christenson cchristenson at brummitt.com
Tue Apr 17 13:47:02 PDT 2007


As clarification, LEED v2.2 requires the use of the Performance Rating
Method from Appendix G, not the ECB method (which was used in previous
versions of LEED).  In fact, in the Reference Guide section of LEED v2.2
titled "Common mistakes made using the Performance Rating Method", the first
mistake listed is "The Energy Cost Budget Method (Section 11) is incorrectly
used rather than the Performance Rating Method (Appendix G) to obtain EA
Credit 1 credit". 

 

Brandon - when I first read Appendix G, I was puzzled by their motivation.
Why rotate the building if you are already evenly distributing glass?  I am
still not sure what the justification from ASHRAE is on that one.  I have
not seen anything from USGBC that gives any exceptions to the rotating
requirement.

 

Charlie Christenson, LEED AP

Brummitt Energy Associates, Inc.

2171 India Street, Suite B

San Diego, CA  92101

tel: 619-531-1126

fax:  619-531-1101

cchristenson at brummitt.com

www.brummitt.com

 

A net-zero carbon company, using www.b-e-f.org/GreenTags

 

Brummitt Energy Associates, Inc. helps you achieve comfortable, highly
energy efficient, cost-effective projects by integrating the building design
with daylighting, electric lighting, and mechanical systems.  Consulting
from early design through construction documentation, we specialize in
energy and daylight modeling, increasing financial incentives, and
documentation for Title 24, LEEDT and CHPS.  20 years experience includes
thousands of buildings, and more than 35 projects pursuing and achieving
LEEDT ratings, from Certified to Platinum.

From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Leader,
Philip
Sent: Tuesday, April 17, 2007 1:02 PM
To: BLDG-SIM at gard.com
Cc: Shawn Gavras
Subject: [BLDG-SIM] App G 2004 question

 

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

 

 

_________________________________________________

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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