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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">My best guess would be the pull-down cooling load. If you’re modeling the 12-hr building as 12 hours occupied and 12 hours unoccupied. The software may let
the building temperature float way up outside of setpoint during the unoccupied hours. Then, when your occupied hours start, the equipment needs extra capacity to pull down the thermal lag of the building to meet setpoint in a reasonable timeframe. Make
sense? Are you modeling it that way?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Michael<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<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-sim-bounces@lists.onebuilding.org [mailto:bldg-sim-bounces@lists.onebuilding.org]
<b>On Behalf Of </b>Sandeep Kachhawa<br>
<b>Sent:</b> Wednesday, February 16, 2011 9:33 AM<br>
<b>To:</b> bldg-sim@lists.onebuilding.org<br>
<b>Subject:</b> [Bldg-sim] HVAC Equipment Sizing<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Dear all<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">I am comparing the epuipment sizing of a day time and a 24 hr office building on EnergyPlus. When I simulate the two while autosizing the hvac equipment, the Nominal Cooling Capacity (W) of the 24 hr building comes less than the day time
building. Though the total energy consumption, as expected, of the 24 hr building is more than the 12 hr building, why the cooling capacity (equipment size) of the 24 hr building is lower than the 12 hr building. In my particular case, for a conditioned area
of around 1600 m2, the cooling capacity for day time and 24 hr building is coming around 146 kW and 128 kW, respectively.<o:p></o:p></p>
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<p class="MsoNormal">What could be the possible reasons for such behaviour?<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">Thanks<o:p></o:p></p>
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<p class="MsoNormal">Sandeep Kachhawa<o:p></o:p></p>
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