<div dir="ltr">Bill,<div><br></div><div>Seems like too big of a guess to me. If the ASHRAE 90.1 committee specifically wanted your supply air temperature reset priority to be airflow first, it seems like that would be simply and explicitly stated. I don't have a copy of the User's Manual for 90.1 in front of me. Perhaps there's further explanation of the meaning of G3.1.3.14 in that document.</div>
<div><br></div><div>In my experience with these systems, I've never been called on my setting of TEMPERATURE-FIRST in system 6 & 8 baselines, so it's likely a moot point. </div><div><br></div><div>-Robby</div>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Fri, Nov 22, 2013 at 6:45 AM, Bishop, Bill <span dir="ltr"><<a href="mailto:bbishop@pathfinder-ea.com" target="_blank">bbishop@pathfinder-ea.com</a>></span> wrote:<br>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Robby,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">My initial interpretation of G3.1.3.14 was similar to yours – of course the SAT is constant at the design condition. But then why bother saying, “The supply
air temperature setpoint shall be constant at the design condition”? Since G3.1.3.14 is about fan power and air flow rate, it makes sense that this refers to the design flowrate. My guess is that the intent is for cooling controls to reset the airflow (to
save fan energy, since that’s what G3.1.3.14 addresses) before resetting the temperature. That strategy can be modeled in eQUEST using RESET-PRIORITY = AIRFLOW-FIRST as I showed below. TEMPERATURE-FIRST can reset the temperature up at the “design condition”
flowrate.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">~Bill<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></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""> Robby Oylear [mailto:<a href="mailto:robbyoylear@gmail.com" target="_blank">robbyoylear@gmail.com</a>]
<br>
<b>Sent:</b> Thursday, November 21, 2013 4:18 PM<br>
<b>To:</b> Bishop, Bill<br>
<b>Cc:</b> <a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> Re: [Equest-users] Appendix G Baseline Systems 6 and 8 - supply air temperature controls?<u></u><u></u></span></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">I'm not sure I follow your interpretation on G3.1.3.14. The supply air temperature setpoint is constant at the design condition regardless of whether you reset airflow or temperature first. At the design condition there will be no reset
occurring because you're by definition, at design. I've always interpreted that whole section of G3.1.3.14 to be referring to the terminal unit fans only. <u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">TEMPERATURE-FIRST makes the most sense to me for accomplishing G3.1.3.12, but I may be biased as in a marine climate resetting temperature up increases economizer hours dramatically.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">-Robby<u></u><u></u></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><u></u> <u></u></p>
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<p class="MsoNormal">On Thu, Nov 21, 2013 at 10:28 AM, Bishop, Bill <<a href="mailto:bbishop@pathfinder-ea.com" target="_blank">bbishop@pathfinder-ea.com</a>> wrote:<u></u><u></u></p>
<div>
<div>
<p class="MsoNormal"><span style="color:#1f497d">I also created an input file template for System 6 which could be used for System 8 with some modification. Comments/mods are welcomed.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">$ *********************************************************</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">$ ** **</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">$ ** Performance Curves **</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">$ ** **</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">$ *********************************************************</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">"G3.1.3.15 VAV Fan Curve fPLR" = CURVE-FIT
</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> TYPE = CUBIC</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> INPUT-TYPE = COEFFICIENTS</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> COEFFICIENTS = ( 0.0013, 0.147, 0.9506, -0.0998 )</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> ..</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">$ *********************************************************</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">$ ** **</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">$ ** HVAC Systems / Zones **</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">$ ** **</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">$ *********************************************************</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">SET-DEFAULT FOR ZONE
</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> TYPE = CONDITIONED</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> MIN-FLOW-RATIO = 0.3 $ Per G3.1.3.14</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> ZONE-FAN-KW/FLOW = 0.00035 $ Per G3.1.3.14</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> ZONE-FAN-RATIO = 0.5 $ Per G3.1.3.14</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> TERMINAL-TYPE = PARALLEL-PIU $ For all zones served by Sys 6 or Sys 8</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> ..</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d">SET-DEFAULT FOR SYSTEM
</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> TYPE = PIU $ For Baseline System 6 and System 8</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> HEAT-SOURCE = ELECTRIC $ Per Table G3.1.1B and User's Manual p.G-23</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> ZONE-HEAT-SOURCE = ELECTRIC $ Per Table G3.1.1B and User's Manual p.G-23</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> HEAT-SIZING-RATI = 1.25 $ Per G3.1.2.2</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> COOL-SIZING-RATI = 1.15 $ Per G3.1.2.2</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> COOL-SOURCE = ELEC-DX $ Per Table G3.1.1B</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> MAX-SUPPLY-T = 92 $ Per G3.1.2.8 (20F above room heat T-Stat</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> HEAT-SET-T = 62 $ = COOL-MAX-RESET-T plus 1F</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> MIN-SUPPLY-T = 56 $ Per G3.1.2.8 (20F below room cool T-Stat</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> COOL-CONTROL = WARMEST $ Per G3.1.3.12</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> ECONO-LIMIT-T = 70 $ Per G3.1.2.7 and Table G3.1.2.6B by climate zone</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> ECONO-LOCKOUT = YES $ (Seems like a reasonable baseline default)</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> COOL-MIN-RESET-T = 56 $ = MIN-SUPPLY-T</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> RESET-PRIORITY = AIRFLOW-FIRST $ Per G3.1.3.12 and G3.1.3.14</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> COOL-MAX-RESET-T = 61 $ Per G3.1.3.12 (5F above MIN-SUPPLY-T)</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> OA-CONTROL = OA-TEMP $ Per G3.1.2.6 and Table G3.1.2.6A</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> FAN-CONTROL = FAN-EIR-FPLR $ Per G3.1.3.15</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> NIGHT-CYCLE-CTRL = CYCLE-ON-ANY $ Per G3.1.2.4</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> FAN-EIR-FPLR = "G3.1.3.15 VAV Fan Curve fPLR" $ Per G3.1.3.15</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> REHEAT-DELTA-T = 36 $ = MAX-SUPPLY-T minus MIN-SUPPLY-T</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> ..</span><u></u><u></u></p>
<p class="MsoNormal"><span style="color:#1f497d"> </span><u></u><u></u></p>
<div>
<p class="MsoNormal"><span style="color:#1f497d"> $ Bill</span><u></u><u></u></p>
</div>
<p class="MsoNormal"><span style="color:#1f497d"> </span><u></u><u></u></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"">
<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a> [mailto:<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a>]
<b>On Behalf Of </b>Bishop, Bill<br>
<b>Sent:</b> Thursday, November 21, 2013 1:14 PM<br>
<b>To:</b> <a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> [Equest-users] Appendix G Baseline Systems 6 and 8 - supply air temperature controls?</span><u></u><u></u></p>
</div>
</div>
<div>
<div>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">ASHRAE Standard 90.1, G3.1.3.12 requires cooling supply air temperature reset for Systems 5 through 8.<u></u><u></u></p>
<p class="MsoNormal">G3.1.3.14 requires “supply air temperature setpoint shall be constant at the design condition” for Systems 6 and 8.<u></u><u></u></p>
<p class="MsoNormal">How should we interpret this and model it in eQUEST (for Systems 6 and 8)?<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">If the “design condition” in G3.1.3.14 means “peak design flow rate”, I suggest the following cooling control settings:<u></u><u></u></p>
<p style="margin-left:.75in">-<span style="font-size:7.0pt"> </span> COOL-CONTROL = WARMEST<u></u><u></u></p>
<p style="margin-left:.75in">-<span style="font-size:7.0pt"> </span> COOL-MIN-RESET-T = 56 $ (assumes 76F cooling T-stat; 56F MIN-SUPPLY-T for 20F difference per G3.1.2.8)<u></u><u></u></p>
<p style="margin-left:.75in">-<span style="font-size:7.0pt"> </span> RESET-PRIORITY = AIRFLOW-FIRST<u></u><u></u></p>
<p style="margin-left:.75in">-<span style="font-size:7.0pt"> </span> COOL-MAX-RESET-T = 61 $ (5F reset per G3.1.3.12; assumes 76F cooling T-stat)<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">Using a RESET-PRIORITY of “TEMP-FIRST” resets the supply air temperature
<i>before</i> the airflow, which does not satisfy the G3.1.3.14 requirement.<u></u><u></u></p>
<p class="MsoNormal">Using a RESET-PRIORITY of “TEMP-FIRST” or “SIMULTANEOUS” does not satisfy the G3.1.3.12 requirement, since temperature is reset well before minimum cooling load conditions are
reached.<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">Does anyone have an alternative/additional suggestion or interpretation?<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">Thanks,<u></u><u></u></p>
<p class="MsoNormal">Bill<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Franklin Gothic Medium","sans-serif"">William Bishop, PE, BEMP, BEAP, LEED AP
<span style="color:#006600">|</span> Pathfinder Engineers & Architects LLP</span></b><u></u><u></u></p>
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