[BLDG-SIM] App G 2004 question
Leonard Sciarra
leonard_sciarra at gensler.com
Wed Apr 18 13:58:40 PDT 2007
Maybe Brandon the question should be have you optimized the building to its site? (constraints and all).
Are you using any daylight harvesting for example? Have you tried to limit the western glazing to reduce some peak cooling loads? Have you tried to introduce earth berms or some other super insulated material on the north side?
Not to beat you up over this, sorry in advance, these may be things out of your control, bad architect (I can say that).
Leonard Sciarra, AIA, LEED ap
312.577.6580 (Dir)
G E N S L E R | Architecture & Design Worldwide
30 West Monroe Street
Chicago IL, 60603
312.456.0123
leonard_sciarra at gensler.com
________________________________
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Brandon Nichols
Sent: Wednesday, April 18, 2007 2:59 PM
To: BLDG-SIM at gard.com
Cc: Shawn Gavras
Subject: [BLDG-SIM] App G 2004 question
Thanks Bill and Mike for your replies,
When while-intentioned theory is designated as policy without practical testing, the resulting requirements stand a much higher chance of ambiguous interpretation and misapplication by those tasked with the implementation.
Is the purpose of LEED to "reward" and "penalize" ... or to build better buildings? The rating system is a tool, and when the tool becomes misshapen to accomplish some spurious objective (e.g. "reward" and "penalize") such that its effectiveness has been reduced for accomplishing its primary objective (i.e. "build better buildings"), then it's time to incorporate implementation feedback to improve the tool in such a way as to restore its previous effectiveness.
But my perception is that there is an open feedback loop at USGBC, caused by deferring to ASHRAE Appendix G and then choosing to ignore all amendments. What is anyone's incentive to expend the effort required to develop an Appendix G amendment in hopes of improving the LEED process, knowing that it will be ignored by USGBC? We all have an obligation to our employers and clients to spend our time wisely.
As for perceived meaninglessness of the orientation averaging requirement, I made the effort to quantify my intuition by rotating the baseline building we're working on (community college science & technology building), and the results are as follows:
0° azimuth: $140,594 annual utility costs
90° azimuth: $140,954
180° azimuth: $140,976
270° azimuth: $140,851
Average: $140,844, a difference of 0.078% from the 0° azimuth
Perhaps for some buildings the rotation exercise will make a difference, but not for this one. Further, the building simply can't be rotated -- it is site constrained.
Note the average needed to be calculated outside of the simulation software, and by strict Appendix G interpretation, this "golden number" needs to be the one against which all EEMs are compared (again, outside of the simulation software), never mind that it's well within the error bounds of the unrotated building simulation.
So this orientation averaging requirement, while it may theoretically sound like a great idea, has the potential to generate pointless busy work for analysts while obfuscating the meaningfulness of a realistic baseline. And the Appendix G fenestration amendment, which could help, is simply ignored by LEED 2.2 fiat.
Improving the language of Appendix G sounds like a worthy midterm goal, however the LEED 2.2 and Appendix G language in their current forms present real implementation problems today. So in terms of LEED applications that are currently in process, is there a method to petition for exceptions against specific requirements which can be demonstrated to be of marginal value to a specific project?
Anyone from USGBC out there?
Thanks
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 Mike Tillou
Sent: Wednesday, April 18, 2007 10:52 AM
To: BLDG-SIM at gard.com
Cc: Shawn Gavras
Subject: [BLDG-SIM] App G 2004 question
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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