<div>We have an exhaust rate of 1.31cfm/sf (or 75cfm per door) which exceeds the minimum requirement greatly. According to what you have mentioned, this should be good as far as creating a negative pressure. </div>
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<div>Just to know, are there any equations to calculate this or is it best determined by physical measurement? <br><br></div>
<div>Deepa</div>
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<div><br> </div>
<div class="gmail_quote">On Wed, Oct 6, 2010 at 12:57 PM, James Hansen <span dir="ltr"><<a href="mailto:JHANSEN@ghtltd.com">JHANSEN@ghtltd.com</a>></span> wrote:<br>
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<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d">I’ve documented many EQc5s and have never been asked to prove anything. For what it’s worth, back when I used Contamw for stair pressurization calcs, even a modest airflow of about 200 CFM per 3 foot door created pressure differences of 0.1-0.15 in. That’s on the order of 25-30 PA. So as long as you’re in the range of 50 CFM per door, you’ll be OK (assuming the door undercut and crack are the only openings into the room).</span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d"> </span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d">This is a major generalization, and there are a lot of parameters that would need to be included to accurately calculate, but it helps me sleep at night knowing 50 CFM / door usually meets this credit.</span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d"> </span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d">And Karen, I don’t follow why you would steer clients away from this credit. Putting full height walls around janitor’s closets and print shops and negatively exhausting them is a good thing, right? </span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d"> </span></p>
<p class="MsoNormal"><b><span style="FONT-SIZE: 11pt; COLOR: teal">GHT Limited<br></span></b><b><span style="FONT-SIZE: 11pt"><span style="COLOR: black">James Hansen</span></span></b><b><span style="FONT-SIZE: 11pt; COLOR: black">, PE, LEED AP</span></b></p>
<p class="MsoNormal"><b><span style="FONT-SIZE: 10pt; COLOR: black">Senior Associate</span></b><b><span style="FONT-SIZE: 11pt; COLOR: black"></span></b></p>
<p class="MsoNormal"><span style="FONT-SIZE: 7.5pt"><span style="COLOR: black">1010 N. Glebe Rd, Suite 200</span></span><span style="FONT-SIZE: 11pt; COLOR: #1f497d"></span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 7.5pt"><span style="COLOR: black">Arlington</span><span style="COLOR: black">, </span><span style="COLOR: black">VA</span><span style="COLOR: black"> </span><span style="COLOR: black">22201-4749</span></span><span style="FONT-SIZE: 11pt; COLOR: black"></span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 7.5pt; COLOR: black">703-338-5754 (Cell)</span><span style="FONT-SIZE: 11pt; COLOR: black"></span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 7.5pt; COLOR: black">703-243-1200 (Office)</span><span style="FONT-SIZE: 11pt; COLOR: black"></span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 7.5pt; COLOR: black">703-276-1376 (Fax)</span><span style="FONT-SIZE: 11pt; COLOR: black"></span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: teal"><a href="http://www.ghtltd.com/" target="_blank"><span style="FONT-SIZE: 10pt">www.ghtltd.com</span></a></span></p>
<p class="MsoNormal"><b><span style="FONT-SIZE: 11pt; COLOR: #31849b"> </span></b></p>
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d"> </span></p>
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<p class="MsoNormal"><b><span style="FONT-SIZE: 10pt">From:</span></b><span style="FONT-SIZE: 10pt"> <a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a> [mailto:<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Karen Walkerman<br>
<b>Sent:</b> Wednesday, October 06, 2010 3:49 PM<br><b>To:</b> James V Dirkes II, PE<br><b>Cc:</b> <a href="mailto:creations.deepa@gmail.com" target="_blank">creations.deepa@gmail.com</a>; Bldg-Sim<br><b>Subject:</b> Re: [Bldg-sim] Negative pressure for EQ cr 5</span></p>
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<div class="im">
<p class="MsoNormal"> </p>
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<p class="MsoNormal">Obtaining a negative pressure difference also requires sealing the space. Door seals, and sealing walls. If you exhaust 0.5 cfm/sf from a room with chicken wire walls, you won't achieve any kind of measurable pressure difference.</p>
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<p class="MsoNormal"> </p></div>
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<p class="MsoNormal">I usually steer clients away from this credit for this very reason (difficulty coupled with measurability)</p></div>
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<p class="MsoNormal"> </p></div>
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<p class="MsoNormal">--</p></div>
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<p class="MsoNormal">Karen</p></div>
<p class="MsoNormal"> </p></div>
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<div class="im">
<p class="MsoNormal">On Wed, Oct 6, 2010 at 3:36 PM, James V Dirkes II, PE <<a href="mailto:jvd2pe@tds.net" target="_blank">jvd2pe@tds.net</a>> wrote:</p></div>
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<div class="im">
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d">Personal opinion:</span></p>
<p><span style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: Symbol">·</span><span style="FONT-SIZE: 7pt; COLOR: #1f497d"> </span><span style="FONT-SIZE: 11pt; COLOR: #1f497d">5 Pa is difficult to (accurately) measure</span></p>
<p><span style="FONT-SIZE: 11pt; COLOR: #1f497d; FONT-FAMILY: Symbol">·</span><span style="FONT-SIZE: 7pt; COLOR: #1f497d"> </span><span style="FONT-SIZE: 11pt; COLOR: #1f497d">1 Pa is impossible outside of a lab</span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d"> </span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d">I don’t know what they were thinking when making these requirements, since they’re not too clear, but I suspect that if you demonstrate .5cfm / sq.ft. and no recirculation you’ll be OK.</span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d"> </span></p></div>
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d"><b>Error! Filename not specified.</b></span></p>
<div class="im">
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d"> </span></p>
<p class="MsoNormal" style="TEXT-ALIGN: center" align="center"><b><span style="FONT-SIZE: 13.5pt; COLOR: #1f497d">The Building Performance Team<br></span><span style="COLOR: #1f497d">James V. Dirkes II, P.E., LEED AP<br>
</span></b><span style="COLOR: #1f497d">1631 Acacia Drive NW<br>Grand Rapids, MI 49504<br>616 450 8653</span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 11pt; COLOR: #1f497d"> </span></p>
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<p class="MsoNormal" style="MARGIN-LEFT: 0.5in"><b><span style="FONT-SIZE: 10pt">From:</span></b><span style="FONT-SIZE: 10pt"> <a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a> [mailto:<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Deepa<br>
<b>Sent:</b> Wednesday, October 06, 2010 2:59 PM<br><b>To:</b> Bldg-Sim<br><b>Subject:</b> [Bldg-sim] Negative pressure for EQ cr 5</span></p></div>
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<div>
<p class="MsoNormal" style="MARGIN-LEFT: 0.5in"> </p>
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<p class="MsoNormal" style="MARGIN-LEFT: 0.5in">Hello all,</p></div>
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<p class="MsoNormal" style="MARGIN-LEFT: 0.5in"> </p></div>
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<p class="MsoNormal" style="MARGIN-LEFT: 0.5in">One of the requirements for EQ Credit 5 is to prove that the areas such as the janitor's closet need to be negatively pressurized to a minimum of 5Pa when doors are closed and 1Pa when doors are open. Generally, in mechanical drawings, the cfm values are mentioned for exhaust fans. </p>
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<p class="MsoNormal" style="MARGIN-LEFT: 0.5in"> </p></div>
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<p class="MsoNormal" style="MARGIN-LEFT: 0.5in">I wanted some insight as to how this pressure difference information can be obtained for both cases. Is there a straightforward calculation? </p></div>
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<p class="MsoNormal" style="MARGIN-LEFT: 0.5in"> </p></div>
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<p class="MsoNormal" style="MARGIN-LEFT: 0.5in"> </p></div>
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<p class="MsoNormal" style="MARGIN-LEFT: 0.5in">Thanks,</p></div>
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<p class="MsoNormal" style="MARGIN-LEFT: 0.5in">Deepa</p></div></div></div></div></div></div>
<div class="im">
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