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<TITLE>RE: Demand limiting / peak-shaving</TITLE>
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<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#1F497D" FACE="Calibri">Sorry to bump this - I’m completely stuck, and I feel like I’m too close to give up. Let me simplify my question to see if avoiding a wall of text helps:</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#1F497D" FACE="Calibri">Is there any way to pull a calculated variable into a user expression? (e.g. the previous hour’s total end-use energy from the electric meter)</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#1F497D" FACE="Calibri">Am I doing this the hard way? How have others done demand limiting (or haven’t you?)</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#1F497D" FACE="Calibri">Thanks!</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT COLOR="#1F497D" FACE="Calibri">Eric</FONT></SPAN></P>
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<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Tahoma">_____________________________________________<BR>
</FONT></SPAN><SPAN LANG="en-us"><B></B></SPAN><SPAN LANG="en-us"><B></B></SPAN><SPAN LANG="en-us"><B><FONT SIZE=2 FACE="Tahoma">Sent:</FONT></B></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Tahoma"> Wednesday, September 29, 2010 2:25 PM<BR>
</FONT></SPAN><SPAN LANG="en-us"><B></B></SPAN><SPAN LANG="en-us"><B></B></SPAN><SPAN LANG="en-us"><B><FONT SIZE=2 FACE="Tahoma">To:</FONT></B></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Tahoma"> equest-users@lists.onebuilding.org<BR>
</FONT></SPAN><SPAN LANG="en-us"><B></B></SPAN><SPAN LANG="en-us"><B></B></SPAN><SPAN LANG="en-us"><B><FONT SIZE=2 FACE="Tahoma">Subject:</FONT></B></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT SIZE=2 FACE="Tahoma"> Demand limiting / peak-shaving</FONT></SPAN></P>
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<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">Has anyone successfully implemented demand limiting? The project I’m working on has a pretty extreme demand ratchet, and there appears to be significant cost savings to be had if I can reduce my peaks. </FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">It looks like the load management feature will have a “peak shaving” option in a future version, although I’m not entirely sure it’s what I’m looking for either. I’m hoping to modify temperature settings at the zone level and have the reduced load “trickle down” to my AHU’s and plant. I’d like to avoid resetting my plant, only to have my fans speed up to compensate.</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">This is essentially the idea:</FONT></SPAN></P>
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<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri">Each zone will have 3 temperature setpoints: Normal, first stage demand limit, second stage demand limit. Each zone can be programmed individually, so critical zones will have all three setpoints at the normal level. As the building demand approaches a setpoint, the first stage limiting setpoints will override the normal setpoints (approximately 2F warmer). If the demand continues to rise towards the setpoint, all zones will be adjusted upwards again to their second stage limiting setpoint (approximately 4F warmer than normal setpoint).</FONT></SPAN></P>
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<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">Ultimately, I think I’m going to need to build a schedule that has user expressions for my summer daytime hours. Unfortunately, I really don’t know what I’m doing with user expressions…</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">I’ve set 5 global parameters for easy modification:</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">RegTemp=74</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">DemTemp1=76</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">DemTemp2=78</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">kWlimit1=700</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">kWlimit2=750</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">And then I’m going to insert the following into my temperature schedules (#VALUE is the variable I’m looking for)</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">{</FONT></SPAN><SPAN LANG="en-us"><B><FONT FACE="Calibri">if</FONT></B></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"> (</FONT></SPAN><SPAN LANG="en-us"><B><FONT FACE="Calibri">#VALUE</FONT></B></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"><#PA(“kWlimit1”))<BR>
</FONT></SPAN><SPAN LANG="en-us"><B> <FONT FACE="Calibri">then</FONT></B></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"> #PA(“RegTemp”)<BR>
</FONT></SPAN><SPAN LANG="en-us"><B> <FONT FACE="Calibri">else</FONT></B></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"> </FONT></SPAN><SPAN LANG="en-us"><B> <FONT FACE="Calibri">if</FONT></B></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"> (</FONT></SPAN><SPAN LANG="en-us"><B><FONT FACE="Calibri">#VALUE</FONT></B></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"><#PA(“kWlimit2”))<BR>
</FONT></SPAN><SPAN LANG="en-us"><B> <FONT FACE="Calibri">then</FONT></B></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"> #PA(“DemTemp1”)<BR>
</FONT></SPAN><SPAN LANG="en-us"><B> <FONT FACE="Calibri">else</FONT></B></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"> #PA(“DemTemp2”)<BR>
</FONT></SPAN><SPAN LANG="en-us"><B> <FONT FACE="Calibri">endif</FONT></B></SPAN><SPAN LANG="en-us"><BR>
<B><FONT FACE="Calibri">endif}</FONT></B></SPAN><SPAN LANG="en-us"></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">What can I replace</FONT></SPAN><SPAN LANG="en-us"><B> <FONT FACE="Calibri">#VALUE</FONT></B></SPAN><SPAN LANG="en-us"><FONT FACE="Calibri"> with that’s going to call up this hour’s (or last hours) demand? Will this work?</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">Thanks!</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="Calibri">Eric</FONT></SPAN></P>
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