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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'>EnergyPlus does include room air velocity term
in Fanger model. It looks like this detail did not make it into the E+’s
Engineering Reference, but a value for forced convection surface heat transfer
coefficient is calculated using:<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-indent:36.0pt'><font size=2 color=navy
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:navy'>Hc = 12.1
* SQRT(velocity)<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>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>However, the calculations take the larger
of either a natural convection Hc or the forced convection Hc, so the air
velocity might not be used in all situations. <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>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Brent<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><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>sanyogita manu<br>
<b><span style='font-weight:bold'>Sent:</span></b> Tuesday, December 15, 2009
11:13 PM<br>
<b><span style='font-weight:bold'>To:</span></b> bldg-sim@lists.onebuilding.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> [Bldg-sim] Query on
DesignBuilder and EnergyPlus: Impact of air velocity on thermal comfort</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<div>
<p class=MsoNormal><span class=postbody><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'>Hi, </span></font></span><br>
<br>
<span class=postbody>I am trying to model the impact of ceiling fans on thermal
comfort in a warm-humid climate, for a naturally ventilated building. Intial
simulation runs obviously show a lot of discomfort with PMV going upto 5.5
during peak summer. We want to model ceiling fans so that the impact of air
velocity on thermal comfort is captured. Naturally this wont lead to achieving
thermal comfort conditions in the space but we feel that it should at least
result in PMV coming down to 4-4.5. I am not sure if doing this is possible in
DesignBuilder but I think one can specify an object called AirVelocity schedule
in EnergyPlus, where one can input air velocity in m/s in one of the fields
(the current EPlus default being 0.137). I want to know that if we modify
(increase) the value of air velocity to about 0.7 (for ceiling fans), would it
be used for comfort calculations? I thought the Fanger comfort model algorithms
use air velocity for calculations but I can't see that happening anywhere in
the Eplus Engineering reference, which could also have been a resultant of my
limited understanding of the subject matter. I also noticed that the Pierce
model takes air velocity into account. Does this mean that we should rather
look at the Pierce model rather than the Fanger model in order to arrive at an
adaptive model of thermal comfort? What we basically want to do is to make sure
that the increased air velocity is used for calculation of PMV in EnergyPlus to
model the impact of ceiling fans. </span><br>
<br>
<span class=postbody>I would be really grateful for any help. </span><br>
<br>
<span class=postbody>Regards, </span><br>
<o:p></o:p></p>
</div>
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'>Sanyogita
Manu<br>
Energy Efficiency Research Associate<br>
USAID ECO-III Project<br>
International Resources Group (IRG)<br>
Hauz Khas, <st1:City w:st="on"><st1:place w:st="on">New Delhi</st1:place></st1:City>
110016<br>
Email: <a href="mailto:smanu@irgssa.com" target="_blank">smanu@irgssa.com</a><o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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