[BLDG-SIM] App G 2004 question
Mike Tillou
miket at etcgrp.com
Wed Apr 18 10:52:18 PDT 2007
Brandon,
I think the thing you need to remember is that the integrity of any
rating system is its ability to be fair and equitable to everyone. This
means that some buildings will get credit for design choices and others
will get penalized. We cannot have a system where you only get to count
the benefits and not the penalties.
There are a lot of things about the Appendix G methodology that are
burdensome but they maintain the integrity of the rating system.
The nice thing about ASHRAE is any member can participate in the process
of improving work like Appendix G. You should propose an alternate
method that would allow a building to be exempt from the "significant
and relatively meaningless calculation burden" you describe.
Mike
Michael Tillou, PE
ETC Group - Energy Engineering for a Sustainable Future
Ph:413-458-9870
-----Original Message-----
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of
Brandon Nichols
Sent: Tuesday, April 17, 2007 7:44 PM
To: BLDG-SIM at gard.com
Cc: Shawn Gavras
Subject: [BLDG-SIM] App G 2004 question
Thanks Bill & Bing for your replies,
Previously I started this topic going again with a
point-by-point description of some implementation problems caused by the
'orientation averaging' and 'fenestration leveling' requirements of LEED
2.2 / 90.1-2004 Appendix G; please refer to that post for further
details.
Here let me try to be as clear and concise as possible:
* There are, perhaps, only 10% of all buildings that can take
advantage of alternate orientations. Most are site-constrained, or have
already been built.
* There are perhaps a greater fraction than 10% of all buildings
that can take advantage of alternate glass distributions, however glass
distribution is also often constrained by site considerations.
* So to accommodate a minority of cases, LEED 2.2 / 90.1-2004
Appendix G seems to impose a significant and relatively meaningless
calculation burden on the majority, by requiring the development of a
fictitious baseline that needs to be manually maintained outside of the
simulation software.
* How can we waive these requirements in LEED 2.2 for projects
that cannot realistically benefit from them, and substitute a "code
minimum" baseline oriented identically and glazed similarly to the
proposed building?
On the last point, even if a site-constrained project could
'theoretically' benefit from orientation averaging or fenestration
leveling, in principle I believe LEED teams should have the option to
forgo that marginal benefit the sake of the simplicity, clarity,
accuracy, and meaningfulness of the comparative calculations.
Thanks for your time, and hard work on LEED...
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
________________________________
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of
William Bahnfleth
Sent: Tuesday, April 17, 2007 2:48 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] App G 2004 question
One of the perceived shortcomings of Ch. 11 as a method for
computing energy savings for green building rating purposes was that it
did not provide sufficient opportunity to take credit for energy savings
through envelope design and building orientation on the site. The cited
portion of Ch. 11 (Table 11.3, item 5) requires all envelope components
of the Budget Building to be the same as the Proposed Building,
eliminating that opportunity.
The parallel part of Appendix G relaxes this constraint in a way
that should make it possible for the Proposed Building to show a greater
reduction in energy cost. This is done by removing self-shading,
distributing fenestration uniformly instead of optimally, and by
averaging the effects of orientation. If someone has done a robust test
of orientation averaging vs. best and worst case orientations that shows
negligible scatter around the mean, I am sure the ECB Subcommittee would
be interested to see it.
The distribution of glazing was made uniform mainly because of
the intent to average multiple orientations.
Bill Bahnfleth
At 04:47 PM 4/17/2007, Charles Christenson wrote:
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 <http://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, LEED(tm) and CHPS.
20 years experience includes thousands of buildings, and more than 35
projects pursuing and achieving LEED(tm) ratings, from Certified to
Platinum.
From: BLDG-SIM at gard.com [ mailto: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 <http://www.albertkahn.com/>
________________________________
From: BLDG-SIM at gard.com [ mailto: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
<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 <http://www.hargis.biz/>
d | 206.436.0400 c | 206.228.8707
o | 206.448.3376 f | 206.448.4450
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_________________________________________________
William P. Bahnfleth, PhD, PE, FASHRAE
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/
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