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<p class=MsoNormal><span style='color:#1F497D'>John, <o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Thanks for the response. I
suppose when designing a UFAD project one needs to utilize controllable
diffusers with adjustable minimum settings or determine acceptable leakage
rates through access-floors and diffusers. The latter, I’m sure,
will take a greater degree of coordination with the architectural team, and
would likely need to be documentable to satisfy the USGBC. Do your
colleagues have any common resources for determining the expected leakage
through access-floor assemblies? The diffuser leakage should be
attainable, I would imagine, from the diffuser manufacturer. <o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>This whole idea of using leakage
to meet ventilation requirements is sort of funny when I think of at least one
premier LEED Platinum building that was constructed in the downtown area here
in Boise, ID. When the air balance was being performed for the air
handlers they determined that they were losing a significant amount of air thru
the floor system. So, the construction/design (I’m not sure which)
decided this was a problem that needed to be solved because leakage was
unacceptable in their minds. The story goes that they proceeded to hire a
bunch of high-school kids to come in and tape every access-floor joint in the
building…floor-by-floor, wing-by-wing until it was completely “sealed
up.”<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>I have no idea what the actual
leakage rate was before or after this process, but I would think for it to be a
good design one would need some documentation or accepted calculation
methodology for accurately determining the real leakage rate thru the floor
system. Also, this leakage rate, though small, should probably be
considered in a space heating load calculation. Furthermore, leakage if
present should be accounted for in energy simulations either as re-heat load,
or reduction in cooling load – which I don’t recall reading in the
UFAD modeling resources I have used.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Lastly, with leakage at 0.25
CFM/SF that will rarely be sufficient to meet minimum ventilation requirements
unless the OA% at the air handler is near 100%. With that in mind, it
seems almost imperative to have controllable minimum setpoints on the UFAD
diffusers so that compliance with ASHRAE 62.1 can be calculated, documented,
and realized.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Quick recap of questions I posed
above:<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span
style='color:#1F497D'><span style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span style='color:#1F497D'>Are there any commonly
accepted calculation methodologies for determining the expected leakage through
access-floor assemblies?<o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span
style='color:#1F497D'><span style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span style='color:#1F497D'>Should UFAD
designers consider leakage as increased space heating load or reduced space
cooling load?<o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span
style='color:#1F497D'><span style='mso-list:Ignore'>3.<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span style='color:#1F497D'>How are energy
simulations accounting for expected leakage?<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Thanks again for your response,<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<div>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:Cheltenham;
color:#A0002F'> </span><span style='font-size:18.0pt;font-family:Cheltenham;
color:#A0002F'>Dan Russell, EIT <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Cheltenham;
color:#A0002F'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Cheltenham;
color:#A0002F'><img width=200 height=174 id="Picture_x0020_1"
src="cid:image001.jpg@01C93F1E.318D4380"
alt="cid:image001.jpg@01C840A4.E711B250"></span><span style='color:#1F497D'><o:p></o:p></span></p>
</div>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
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<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
bldg-rate-bounces@lists.onebuilding.org
[mailto:bldg-rate-bounces@lists.onebuilding.org] <b>On Behalf Of </b>John E.
Beeson<br>
<b>Sent:</b> Wednesday, November 05, 2008 7:14 AM<br>
<b>To:</b> bldg-rate@lists.onebuilding.org<br>
<b>Subject:</b> Re: [Bldg-rate] ASHRAE 62.1 Compliance with Underfloor-Air
Distribution<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>Dan,</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>I passed your note over to some experienced UFAD mechanical
engineers (they have done many projects with UFAD that met LEED and ASHRAE
62.1).</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>The response is below. I hope this helps some!</span><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>John</span><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> </span><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p>
<div class=MsoNormal align=center style='text-align:center'><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'>
<hr size=2 width="100%" align=center>
</span></div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <strong><span
style='font-family:"Tahoma","sans-serif"'>Sent:</span></strong> Tuesday,
November 04, 2008 4:15 PM<br>
<b>Subject:</b> RE: ASHRAE 62.1 Compliance with Underfloor-Air Distribution<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'>A combination of factors and options must be considered. Most UFAD
systems include large open office areas, for which C02 monitoring can be
applied, and there is a non-trivial amount of general leakage of supply air
through the floor and the diffusers, even in minimum settings. Depending on the
UF plenum pressure and the floor and carpet systems used, this may be 0.25 CFM
per SF, beyond what the diffusers provide at their minimum. Some UFAD diffusers
have definable minimum stops, and some (e.g. the Titus TAF-LV system) can be
designed and controlled to provide a minimum aperture area, which, in
conjunction with known underfloor plenum pressures, can provide defined amounts
of supply air.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy'><o:p> </o:p></span></p>
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style='font-size:12.0pt;font-family:"Times New Roman","serif"'>
<hr size=2 width="100%" align=center>
</span></div>
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style='font-size:12.0pt;font-family:"Times New Roman","serif"'>
<hr size=2 width="100%" align=center>
</span></div>
<p class=MsoNormal style='margin-bottom:12.0pt'><b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> bldg-rate-bounces@lists.onebuilding.org
[mailto:bldg-rate-bounces@lists.onebuilding.org] <b>On Behalf Of </b>Dan
Russell<br>
<b>Sent:</b> Tuesday, November 04, 2008 11:07 AM<br>
<b>To:</b> bldg-rate@lists.onebuilding.org<br>
<b>Subject:</b> [Bldg-rate] ASHRAE 62.1 Compliance with Underfloor-Air
Distribution</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal>Hello All,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I am struggling with determining how the common UFAD systems
today are meeting ASHRAE 62.1. The systems which I have seen utilize
floor grilles with either a motorized damper controlled via wall-mounted t-stat
or a manual damper. When the space is satisfied the dampers close and all
of a sudden there is no supply air entering the space. This is also the
case during all heating modes I have observed in UFAD systems. During
heating mode for these systems the primary supply air is completely shut-off and
the space is heated using 100% re-circulated air from the space. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I recently attended a seminar by a UFAD manufacturer where
one of the speakers was a chief engineer for the company. After the
seminar I posed this question to him, only to have him respond by saying that
it’s a tough issue to tackle and he’s not sure how compliance would
be met. I’ve also been told that since heating only takes place on
the perimeter that ventilation is drawn from interior zones. I’ve
also been told, “Well we generally only see corridors on the perimeter of
buildings with UFAD.” To my knowledge ASHRAE 62.1 doesn’t
allow ventilation from interior zones to compensate for perimeter zones that
have little or no primary air flow. Also, ASHRAE 62.1 requires ventilation
in corridors anyways so this argument seems to be just as weaselly.
ASHRAE 62.1 requires zones to be adequately ventilated during all load
conditions, which includes no load or heating load<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>UFAD seems to be touted as the Messiah of multi-story office
HVAC, but the lack of ventilation air appears to be a glaring omission.
Am I missing something about these systems? <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Does anyone know how to design a UFAD system that complies
with ASHRAE 62.1? Surely there have been several successful LEED
certifications for projects utilizing UFAD technology; does anyone know
if the USGBC has given guidelines for this issue?<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Thanks,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:Cheltenham;
color:#A0002F'> </span><span style='font-size:18.0pt;font-family:Cheltenham;
color:#A0002F'>Dan Russell, EIT <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Cheltenham;
color:#A0002F'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:Cheltenham;
color:#A0002F'><img width=200 height=174 id="Picture_x005f_x0020_1"
src="cid:image001.jpg@01C93F1E.318D4380"
alt="cid:image001.jpg@01C840A4.E711B250"></span><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
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