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<p class=MsoNormal>I am trying to figure out how to best simulate the intended
behavior of 100% OA VAV heating/ventilating system with night time precooling
of thermal mass. At the moment, I don’t care much about accuracy of
the energy performance. I am more concerned with forcing the system to behave
in specific ways, and observing the impact that this has on temperatures.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I’m currently using the system type UVT, since it seemed
simplest, though the HVSYS might be more appropriate.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>During the day, I want the system to supply air as follows:<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span
style='mso-list:Ignore'>1)<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>If the outdoor temp is less than the zone temp, supply
up to a set CFM/SF (which I will vary over several runs) to utilize free cooling<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span
style='mso-list:Ignore'>2)<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>If the zone is occupied, supply 15 CFM/person (or
control by DCV, but if that’s more complex to set up I may not bother for
now.)<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span
style='mso-list:Ignore'>3)<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>If the zone is unoccupied, supply 0.15 CFM/SF<o:p></o:p></p>
<p class=MsoNormal>If #1 is hard to implement, I could live with just #2 and #3
for now.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>During the night, I want the system to supply a flow rate
that I specify, preferably on a square foot basis. (I plan to vary this
from 0.5 CFM/SF to 2.0 CFM/SF to observe how this impact daytime temperatures,
to figure out the right night time cooling rate and time period.) I want
it to provide this airflow regardless of the OA temp or zone temp –
I’ll control it with a schedule to prevent night time cooling in
winter. Mostly, I want to make sure that I’m getting as much air to
the zones as I think I am – I don’t want the air volume to be
overridden by e.g. the zone thermostat.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I can turn the fan on and off via a schedule. The two
things I’m not sure how to do are:<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l1 level1 lfo4'><![if !supportLists]><span
style='mso-list:Ignore'>1)<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>Disable all economizer activity. This is a 100%
OA system. I can set MIN-OUTSIDE-AIR (At the system level) to 1.0, but is
that enough? I don’t want it overridden by zone settings.<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l1 level1 lfo4'><![if !supportLists]><span
style='mso-list:Ignore'>2)<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>Control the airflow on a CFM/SF basis at night, while
avoiding any override by the zones or other inputs. When the fans run, I
want them to supply the airflow I specify, period.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Thanks for any suggestions you can offer.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Brent<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:9.0pt;
font-family:"Arial","sans-serif";color:gray'>Brent Eubanks<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:9.0pt;
font-family:"Arial","sans-serif";color:gray'>Mechanical Designer, Taylor
Engineering, LLC<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:9.0pt;
font-family:"Arial","sans-serif";color:gray'>1080 Marina Village Parkway, Suite
501, Alameda CA 94501<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:9.0pt;
font-family:"Arial","sans-serif";color:gray'>(510) 473-1164 direct, (510)
749-9135 office<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:9.0pt;
font-family:"Arial","sans-serif";color:gray'>(510) 749-9136 fax<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:4.0pt;
font-family:"Arial","sans-serif";color:gray'><o:p> </o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:9.0pt;
font-family:"Arial","sans-serif";color:gray'><a
href="mailto:beubanks@taylor-engineering.com">beubanks@taylor-engineering.com</a><o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:9.0pt;
font-family:"Arial","sans-serif";color:gray'><a
href="http://www.taylor-engineering.com">www.taylor-engineering.com</a> <o:p></o:p></span></p>
<p class=MsoNormal><o:p> </o:p></p>
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