<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:12pt"><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;">Peter,<br>I think as Vikram mentioned, it depends on the total exhaust (cumulative exhaust of all the fume hoods). If the total exhaust exceeds 15,000cfm, then the baseline needs to have AT LEAST one of the following:<br><br>1. VAV hood exhaust till a 50% min turn down over the total CFM. Hence you could only take advantage of a lower VAV set point on the actual equipment.<br>2. Make-up air. Separate make-up air with supply temperature very close to room temperatures.<br>3. Heat recovery . If the building has both VAV and HR, then you should be able to take full benefits of heat recovery or vise-versa.<br> <br>Hence if your total fume hood exhaust is lower than 15,000 cfm, then you should be able
to take advantage of VAV fume hood exhaust over constant volume exhaust.<br><br>Does this make sense?<br><br>Gerald<br><br><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> Peter Simmonds <peter.simmonds@ibece.net><br><b><span style="font-weight: bold;">To:</span></b> Aleka Pappas <APappas@enermodal.com>; bldg-sim@lists.onebuilding.org<br><b><span style="font-weight: bold;">Sent:</span></b> Wed, September 1, 2010 3:39:42 AM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [Bldg-sim] Modeling fume hood exhausts<br></font><br>
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<p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Thanks for all the help. Here is another angle I am coming from.</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Assuming the base case were to be a traditional fume hood exhaust
system which used constant volume fans in order to create the 3000 fpm
discharge velocity. If the fume hoods have sash control the there is an outside
air by-pass on the fan header, so down stream VAV and upstream constant volume
exhaust fans. I know these constant volume fans can be staged to form a
'quasi' variable exhaust. So if this were the base case then one could apply
the list of various innovations on how to apply variable exhaust flow to the
proposed model.</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">The ASHRAE 90.1 6.5.7.2 isnt really a solution, however Aleka
you mention Lab 21, have you had any luck in getting this accepted by the LEED
meanies?</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p>
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<p class="MsoNormal" style=""><b><span style="font-size: 11pt; font-family: "sans-serif";">Peter
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</span></b><b><i><span style="font-size: 10pt; font-family: "sans-serif"; color: gray;">Ideas for the built environment</span></i></b><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"></span></p>
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<p class="MsoNormal"><b><span style="font-size: 10pt; font-family: "sans-serif"; color: windowtext;">From:</span></b><span style="font-size: 10pt; font-family: "sans-serif"; color: windowtext;"> Aleka Pappas
[mailto:APappas@enermodal.com] <br>
<b>Sent:</b> Tuesday, August 31, 2010 2:41 PM<br>
<b>To:</b> bldg-sim@lists.onebuilding.org<br>
<b>Subject:</b> Re: [Bldg-sim] Modeling fume hood exhausts</span></p>
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<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="font-family: "sans-serif";">I just
spent a while digging through all the latest docs on modeling labs for a LEED
analysis (90.1-2004, 90.1-2007, addenda, & Labs 21). This is my
interpretation:</span></p>
<ul type="disc">
<li class="MsoNormal" style="">If the <i>building</i> has fume hood exhaust over
15,000 cfm, the Baseline system is VAV, and exhaust is turned down to at
least 50% for unoccupied hours. I am modeling the unoccupied turn
down rate the same in the Baseline as in the Proposed models, because how
low it can go at night depends on the type of lab (ie: the project doesn't
get more credit for turning down to 20%). This is from Labs 21, and
90.1 (2004 or 2007) section 6.5.7.2.</li>
<li class="MsoNormal" style="">A project can claim energy savings for demand
controlled fume hoods during occupied hours if the controls are automatic
(Labs21 has some schedules for guidance in modeling this).</li>
<li class="MsoNormal" style="">Energy recovery is not modeled in the Baseline
(see 90.1-2007 G3.1.2.10 Exception h).</li>
</ul>
<p class="MsoNormal" style="margin-bottom: 12pt;">Let me know if you have a
different interpretation....I don't think all these issues are laid out in
detail for modelers yet.</p>
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<p class="MsoNormal"><b><span style="font-family: "sans-serif"; color: rgb(0, 102, 0);">Aleka Pappas</span></b></p>
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<p class="MsoNormal"><span style="font-size: 10pt; font-family: "sans-serif"; color: rgb(0, 102, 0);">Building Energy Engineer</span> </p>
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<p class="MsoNormal"><br>
On 8/31/2010 12:35 PM, varun kulkarni wrote: </p>
<div>
<p class="MsoNormal">I think it also depends on the software you are using to
model a fume hood. Because if exhaust is specified more than the supply
due to the hood, the software may disregard the lower supply and equate
the higher value of exhaust to the supply. I am also trying to model a
VAV exhaust fume hood and facing a lot of problems doing it. So you have to
figure out a way to control you exhaust by altering your VAV supply.</p>
</div>
<div>
<p class="MsoNormal" style="margin-bottom: 12pt;">If you know some other way,
please let me know also :)</p>
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<div>
<p class="MsoNormal">On Tue, Aug 31, 2010 at 2:23 PM, Sami, Vikram <<a rel="nofollow" ymailto="mailto:Vikram.Sami@perkinswill.com" target="_blank" href="mailto:Vikram.Sami@perkinswill.com">Vikram.Sami@perkinswill.com</a>>
wrote:</p>
<p class="MsoNormal">I think that depends on the total volume of exhaust. I don't
have it in front of me, but I think if your exhaust is more than a certain
amount you have to have either energy recovery to fifty percent or vav flow.<br>
<br>
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-----Original Message-----<br>
From: Peter Simmonds [mailto:<a rel="nofollow" ymailto="mailto:peter.simmonds@ibece.net" target="_blank" href="mailto:peter.simmonds@ibece.net">peter.simmonds@ibece.net</a>]<br>
Sent: Tuesday, August 31, 2010 12:09 PM Central Standard Time<br>
To: <a rel="nofollow" ymailto="mailto:bldg-sim@lists.onebuilding.org" target="_blank" href="mailto:bldg-sim@lists.onebuilding.org">bldg-sim@lists.onebuilding.org</a><br>
Subject: [Bldg-sim] Modeling fume hood exhausts<br>
<br>
Can anyone tell me when modeling a lab system with fume hoods as to whether the
baseline systems are to be modeled as constant volume?<br>
<br>
(subsequent alternatives will have variable volume fume hoods).<br>
<br>
<br>
<br>
Peter Simmonds,Ph.D.<br>
Senior Associate<br>
<br>
IBE Consulting Engineers<br>
14130 Riverside Drive, Suite 201<br>
Sherman Oaks, CA 91423<br>
p: (818) 377-8220 x246 f: (818) 377-8230<br>
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<p style="margin: 0in 0in 0.0001pt;"><a rel="nofollow" name="SafeHtmlFilter__MailAutoSig"><span style="font-family: "sans-serif";">Thanks
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<p style="margin: 0in 0in 0.0001pt;"><span style="font-family: "sans-serif";">Sincerely,</span></p>
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