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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'>Hello Kevin,<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'>I have not yet modeled this but here is
what I am planning to do:<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>
<ol style='margin-top:0in' start=1 type=1>
<li class=MsoNormal style='color:navy;mso-list:l0 level1 lfo1'><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial'>Determine
the total floor area of zones with occupancy sensor control. Let’s
call it “Area X”<o:p></o:p></span></font></li>
<li class=MsoNormal style='color:navy;mso-list:l0 level1 lfo1'><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial'>Estimate
the amount of time that any one zone would be unoccupied. For
purposes of this explanation, assume it is 15% (per the ASHRAE 90.1-2004
Table G3.2). <o:p></o:p></span></font></li>
<li class=MsoNormal style='color:navy;mso-list:l0 level1 lfo1'><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial'>Multiply
“Area X” by 15% to determine an equivalent floor area that
would be unoccupied continuously. Let’s call this “Area
Y”<o:p></o:p></span></font></li>
<li class=MsoNormal style='color:navy;mso-list:l0 level1 lfo1'><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial'>Look
at all of your zones used to develop “Area X” and determine
the relative proportion of areas that have north, east, south, west exposures
and are in the core of the building. Let’s call the proportion
of area in the north exposure “N”<o:p></o:p></span></font></li>
<li class=MsoNormal style='color:navy;mso-list:l0 level1 lfo1'><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial'>Multiply
“Area Y” by each of these different proportions (e.g. “Area
Y” x “N”) to determine how much unoccupied space needs
to be represented. Review your list of “Area X” zones
to find the ones with approximately the correct floor area corresponding
to the requirements for the different exposures – these will be
normally unoccupied spaces. Depending on how the zones were
initially modeled, you may need to split some zones to make specialized “unoccupied”
zones (this could get pretty time intensive unless you anticipate having
to do this when the model geometry is assembled). The purpose of going
through the hassle of identifying zones in each of the different exposures
is to model the impact of occupancy sensor control on the average space.
<o:p></o:p></span></font></li>
<li class=MsoNormal style='color:navy;mso-list:l0 level1 lfo1'><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial'>Within
the normally unoccupied zones, set the minimum airflow in the Airside
Systems/Zone/Airflow tab to 0 cfm and change the occupancy, plug,
lighting, heating, and cooling schedules to use an unoccupied schedule (use
the “FRACTION ALWAYS OFF YEAR”, “COOLING SETBACK YEAR”,
and “HEATING SETBACK YEAR” schedules you have already made).<o:p></o:p></span></font></li>
</ol>
<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'>It seems like this approach could
potentially work and would be fairly accurate for a building where the aggregate
unoccupied periods are distributed randomly throughout the typical workday.
If there are separate mechanical systems, the procedure above would need to be
replicated for each system. This approach would probably work for a
typical office but may not work for an operation with mandatory lunch hours.
In reality, the typical zone would probably not float all the way back to its
unoccupied setpoint since the unoccupied periods during normal building hours
will be fairly brief (<1 hr?). Assuming that some zones are always at
setback temperatures does decrease conduction gain/losses, however, this component
of space load is generally small relative to solar, equipment, and lighting loads
during occupied periods in non-residential spaces. The most
significant uncertainty in this approach is the guesstimate of the fraction of
time that the typical space will be unoccupied.<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'>If there are periods when many zones are
likely to be unoccupied at the same time, things can get a bit more complicated.
Specialized schedules can be made for occupancy, plug, lighting, heating and cooling,
and you would need to use the minimum airflow schedule option in Airside
Systems/Zone/Airflow. <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'>Is this what others have done? Does
it seem reasonable?<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'>Eric<o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=2 color=navy face=Calibri><span style='font-size:
11.0pt;color:navy'> </span></font><o:p></o:p></p>
</div>
<div>
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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>Kevin Kyte<br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, October 29, 2008
4:24 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] Occupany
Sensor on VAV Box</span></font><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'><o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>Greetings,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>Would
anyone who has evaluated energy savings through the use of occupancy sensors
controlling VAV boxes please share some experience, do’s and
don’ts, etc.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>I
believe the VAV boxes would have a minimum setback to 0% or 10% flow and
possibly no reheat in the summertime. I have been trying to model this
with little success. Is it possible to do using freeware or should I start
constructing hourly reports. Thank you all for your assistance.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>Kevin<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt;font-family:"Times New Roman"'><o:p> </o:p></span></font></p>
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face="Times New Roman"><span style='font-size:12.0pt;font-family:"Times New Roman"'>
<hr size=2 width="100%" align=center>
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