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<title>RE: [Bldg-sim] Exhaust, outside air and infiltration for LEED</title>
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I appreciate everyone’s detailed
responses to my query. The project I’m modeling has 100% OA VAV for most
of the building, while the App. G baseline is System 3 – Constant volume packaged
rooftops. This is a NY State project that has to be “designed to meet the
criteria for LEED” but will not likely go through the certification
process. One thing I learned is that, even though OA was identical in my
baseline and proposed models (because “I modeled it that way”) –
it didn’t actually turn out to be true. Custom hourly eQUEST reports
showed nearly twice as much annual OA CFM in my baseline than in my proposed. Ouch.
Glad I checked.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Regards,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Bill<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</span></font></b><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Fred Porter<br>
<b><span style='font-weight:bold'>Sent:</span></b> Monday, November 10, 2008
10:22 AM<br>
<b><span style='font-weight:bold'>To:</span></b> Paul Riemer; Mitchell Dec;
Brandon Nichols; Michael Tillou; Andrew Craig<br>
<b><span style='font-weight:bold'>Cc:</span></b> bldg-sim@lists.onebuilding.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [Bldg-sim] Exhaust,
outside air and infiltration for LEED</span></font><o:p></o:p></p>
</div>
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<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>Interesting. We
recently decided not to "take credit" for substantial
cascade/transfer air in a restaurant EAc1 app (i.e. the transfer air from
dining to kitchen/hood was included in the baseline model). Our
experience is that this mode has been extremely common for many,
many years in commercial and school kitchens. (And it's very inexpensive,
sometimes decreasing construction costs.) We felt taking credit
for it did not meet the spirit of the PRM. Maybe if one needed to build
all kinds of transfer ducting in a hotel, then it might seem like an
improvement worthy of recognition...<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>I could go on
with a rant about the opacity of the credit review process, loopholes,
"consensus" standards, etc. But actual work beckons.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> <o:p></o:p></span></font></p>
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<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>Fred<o:p></o:p></span></font></p>
</div>
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<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
12.0pt;margin-left:0in'><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma'><br>
>>> "Andrew Craig" <AndrewC@InterfaceEng.Com>
11/7/2008 3:42 PM >>><br>
We have successfully taken credit for reduced OSA rates in a number of
applications where a "cascading" make-up air system has been
designed. In a kitchen hood application for instance, the traditional
design might bring in 100% OSA to offset the hood exhaust from a separate
intake or unit. In certain projects (schools come to mind), this make-up
air can be transferred into the space via adjacent spaces with high OSA
requirements (i.e. commons), thus saving all or a portion of the mechanical
energy to heat/cool this air. We have always taken the path of the
exceptional calculation for LEED purposes because this is definitely a grey
area as far as Appendix G is concerned.<br>
<br>
<br>
-----Original Message-----<br>
From: bldg-sim-bounces@lists.onebuilding.org on behalf of Mitchell Dec<br>
Sent: Fri 11/7/2008 1:50 PM<br>
To: Paul Riemer; Brandon Nichols; Michael Tillou<br>
Cc: bldg-sim@lists.onebuilding.org<br>
Subject: Re: [Bldg-sim] Exhaust, outside air and infiltration for LEED<br>
<br>
Bill, Paul, Mike, et al -<br>
<br>
<br>
<br>
We also have not mentioned another item relative to Appendix G, which<br>
requires sizing the flow rate based on a 20-degree delta T. If the<br>
system is a 100% OSA unit, and the baseline is sized for a 20-degree<br>
space-to-coil temperature differential, what happens if the makeup air<br>
unit is not designed with a 20-degree delta-T? Then it is possible the<br>
peak CFM rates could potentially vary. So right there, we could<br>
potentially have a contradiction between 2 lines in Appendix G - (1) OSA<br>
ventilation rates are to be identical, and (2) The baseline AHU flow<br>
rate is specified by a 20-degree delta T - now, which statement in<br>
Appendix G "over rules" the other?<br>
<br>
<br>
<br>
This seems like this should fall under the Exceptional Calculation<br>
methodology to explicitly document where the savings come from, and<br>
whether the savings are justified...<br>
<br>
<br>
<br>
Also regarding an earlier item from this thread, that one cannot take<br>
credit for UFAD and displacement ventilation systems with reduced CFM<br>
rates - as long as the OSA CFM rates are identical, then credit can be<br>
taken from the UFAD/DV system design. You'll be providing the same OSA,<br>
but different Total CFM rates could be calculated based on the different<br>
mixed air temperatures and designed coil leaving temperatures. This can<br>
be either a positive or negative, which truly depends on the climate and<br>
the ability to maximize the economizer hours...<br>
<br>
<br>
<br>
<br>
<br>
Mitch Dec<br>
Senior Energy Analyst, EIT<br>
<br>
LEED(r) Accredited Professional<br>
<br>
<br>
<br>
<br>
<<a href="http://www.glumac.com/">http://www.glumac.com/</a>><br>
<br>
________________________________<br>
<br>
320 SW Washington, <st1:address w:st="on"><st1:Street w:st="on">Suite</st1:Street>
200</st1:address><br>
<st1:place w:st="on"><st1:City w:st="on">Portland</st1:City>, <st1:State w:st="on">OR</st1:State>
<st1:PostalCode w:st="on">97204-2640</st1:PostalCode></st1:place><br>
T. 503.227.5280 F. 503.274.7674<br>
<br>
Thinking. Inside the building.<br>
www.glumac.com <<a href="http://www.glumac.com/">http://www.glumac.com/</a>> <br>
<<a href="http://www.glumac.com/">http://www.glumac.com/</a>><br>
<br>
<br>
<br>
<br>
<br>
From: bldg-sim-bounces@lists.onebuilding.org<br>
[<a href="mailto:bldg-sim-bounces@lists.onebuilding.org">mailto:bldg-sim-bounces@lists.onebuilding.org</a>]
On Behalf Of Paul Riemer<br>
Sent: Friday, November 07, 2008 1:37 PM<br>
To: 'Brandon Nichols'; Michael Tillou<br>
Cc: bldg-sim@lists.onebuilding.org<br>
Subject: Re: [Bldg-sim] Exhaust, outside air and infiltration for LEED<br>
<br>
<br>
<br>
Bill,<br>
<br>
This is a fascinating convergence of issues. <br>
<br>
<br>
<br>
Appendix G's requirement for the same minimum ventilation rate in the<br>
baseline as the proposed is true but also a bit incomplete when<br>
considering a design of a 100% OA VAV systems serving fume hoods.<br>
<br>
<br>
<br>
We have a similar scenario of a small building with likely VAV hoods,<br>
possibly lower flow, likely served by a 100% outside air system BUT with<br>
my favorite added complexity of district heating and cooling. <br>
<br>
<br>
<br>
Alas, while I was scratching my head, the client abandoned their LEED<br>
goal.<br>
<br>
<br>
<br>
So I have not fully solved it for myself and cannot solve for it your<br>
project but I do suggest the following actions:<br>
<br>
1) Read the 90.1-2004 prescriptive requirements for certain systems<br>
serving fume hoods to be VAV or have heat recovery. <br>
<br>
2) Read the 90.1-2004 Appendix G base system selection section<br>
<br>
3) Now read those same sections in 90.1-2007 and ponder which changes<br>
represent revisions and which ones represent clarifications of original<br>
intent<br>
<br>
4) And maybe read the User's Manuals too<br>
<br>
5) Consider the exceptional calculation method as the venue to claim<br>
energy savings, that you consider real but are not explicitly allowed or<br>
defined by the document, for consideration by the LEED reviewer<br>
<br>
6) Research the existing CIR's<br>
<br>
7) Before spending numerous hours on an approach that may or may not be<br>
accepted, buy a CIR and propose your tact to the USGBC itself. If they<br>
reject yours they almost certainly will dictate a new tact that their<br>
reviewer would be obligated to accept for your project.<br>
<br>
<br>
<br>
And lastly, do not wade too much further through this on a Friday<br>
afternoon unless you have to do so. For me, tasks like this should be<br>
tackled early in the day and early in the week.<br>
<br>
<br>
<br>
Good luck,<br>
<br>
<br>
<br>
Paul<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
________________________________<br>
<br>
From:
bldg-sim-bounces@lists.onebuilding.org<br>
[<a href="mailto:bldg-sim-bounces@lists.onebuilding.org">mailto:bldg-sim-bounces@lists.onebuilding.org</a>]
On Behalf Of <st1:City w:st="on"><st1:place w:st="on">Brandon</st1:place></st1:City><br>
Nichols<br>
Sent: Friday, November 07, 2008 2:47
PM<br>
To: Michael Tillou<br>
Cc: bldg-sim@lists.onebuilding.org<br>
Subject: Re: [Bldg-sim] Exhaust,
outside air and infiltration<br>
for LEED<br>
<br>
My two cents...<br>
<br>
The same OSA for baseline vs
as-designed makes sense for<br>
occupant-required OSA, such that there is no reward for compromising<br>
occupant health to gain LEED points.<br>
<br>
However, that fraction of the
fumehood OSA over and above<br>
occupancy-required is process OSA, an opportunity where LEED should be<br>
encouraging savings. Now I'm not saying they do, just that they<br>
should...<br>
<br>
And after rereading the requirements
it shakes out that LEED<br>
really doesn't give credit for reducing process outside air loads, keep<br>
the parametric run in your model -- the local utility may see things<br>
differently, and 'recognize you' with a big fat rebate check.<br>
<br>
Cheers<br>
<br>
Brandon Nichols<br>
BW Nichols PE<br>
<st1:place w:st="on"><st1:City
w:st="on">Seattle</st1:City> <st1:State w:st="on">WA</st1:State></st1:place><br>
206-228-8707<br>
<br>
On Fri, Nov 7, 2008 at 11:53 AM,
Michael Tillou <<br>
michael.tillou@gmail.com> wrote:<br>
<br>
You are correct that Appendix G
requires outside air to be the<br>
same for both as-designed and baseline models. You would not be able to<br>
claim savings for reduced ventilation airflow from a more efficient fume<br>
hood. Similarly you cannot claim credit for reduced ventilation<br>
airflow on displacement ventilation and UFAD systems.<br>
<br>
<br>
<br>
However I see no reason why you
wouldn't be able to claim the<br>
fan energy savings associated with a more efficient fume hood.<br>
<br>
<br>
<br>
Mike<br>
<br>
<br>
<br>
Michael Tillou, PE, LEED<br>
<br>
Tillou Engineering, LLC<br>
<br>
<st1:place w:st="on"><st1:City
w:st="on">Williamstown</st1:City>, <st1:State w:st="on">MA</st1:State> <st1:PostalCode
w:st="on">01267</st1:PostalCode></st1:place><br>
<br>
P: 413-458-9870 C: 413-652-1087<br>
<br>
________________________________<br>
<br>
From:
bldg-sim-bounces@lists.onebuilding.org [mailto:<br>
bldg-sim-bounces@lists.onebuilding.org] On Behalf Of <st1:PersonName w:st="on">Bishop,
Bill</st1:PersonName><br>
Sent: Friday, November 07, 2008 9:04
AM<br>
To: bldg-sim@lists.onebuilding.org<br>
Subject: [Bldg-sim] Exhaust, outside
air and infiltration for<br>
LEED<br>
<br>
The mechanical engineer for a campus
laboratory building with<br>
100% OA wants to claim energy savings for reduced exhaust from more<br>
efficient fume hoods. (Established design practice uses hoods with 100<br>
fpm flow - they are installing 70 fpm hoods. This reduces peak exhaust<br>
from 700 to 490 CFM per hood.) My approach has always been to keep<br>
outside air, exhaust and infiltration flows identical between the<br>
proposed and baseline models (except for DCV). (This was not easy for<br>
this model with proposed VAV and baseline constant volume packaged<br>
rooftops.)<br>
<br>
<br>
<br>
Has anybody successfully claimed
OA/exhaust/infiltration savings<br>
for a LEED project?<br>
<br>
<br>
<br>
Thanks,<br>
<br>
Bill<br>
<br>
<br>
<br>
William Bishop, EIT, LEED(r) AP |
Pathfinder Engineers LLP<br>
<br>
Mechanical Engineer<br>
<br>
<br>
<br>
<st1:Street w:st="on"><st1:address
w:st="on">3300 Monroe Ave., Suite 306</st1:address></st1:Street><br>
<st1:place w:st="on"><st1:City
w:st="on">Rochester</st1:City>, <st1:State w:st="on">NY</st1:State> <st1:PostalCode
w:st="on">14618</st1:PostalCode></st1:place><br>
<br>
TEL (585) 218-0730 Ext. 114<br>
FAX (585) 218-0737<br>
<br>
bbishop@pathfinderengineers.com<br>
<br>
<br>
<br>
www.pathfinderengineers.com<br>
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