Hi Marcus, <div><br></div><div>Also pay attention to better glass in the proposed design. In a cooling-dominated building, better window means the heat can not easily escape from the building. You will not easily get credit from improving your window here. </div>
<div> <br clear="all"><div><font face="comic sans ms,sans-serif">Regards, </font></div>
<div><font face="comic sans ms,sans-serif"></font> </div>
<div><font face="comic sans ms,sans-serif">Cheney</font></div>
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<div><font face="comic sans ms,sans-serif">LinkedIN @ </font><a href="http://ca.linkedin.com/pub/yu-cheney-chen/27/637/72b" target="_blank"><font face="comic sans ms,sans-serif">http://ca.linkedin.com/pub/yu-cheney-chen/27/637/72b</font></a><font face="comic sans ms,sans-serif"> </font></div>
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<br><br><div class="gmail_quote">On Mon, May 23, 2011 at 3:18 PM, James V Dirkes II, PE <span dir="ltr"><<a href="mailto:jim@buildingperformanceteam.com">jim@buildingperformanceteam.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div lang="EN-US" link="blue" vlink="purple"><div><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Dear Marcus,</span></p><p><span style="font-size:11.0pt;font-family:Symbol;color:#1F497D"><span>·<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;color:#1F497D">It seems that your Baseline system, at >5 floors, should be VAV with a chiller instead of a heat pump (using LEED 2009).</span></p>
<p><span style="font-size:11.0pt;font-family:Symbol;color:#1F497D"><span>·<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;color:#1F497D">As modeled, your baseline DOES have a notably higher COP, so it may well use less energy. <u>Part load performance</u> will have a significant effect, so you may want to check and compare those curves.</span></p>
<p><span style="font-size:11.0pt;font-family:Symbol;color:#1F497D"><span>·<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;color:#1F497D">Also check pump delta T and total pressure drop. If you continue with a non-chiller system, pump energy is a significant factor. If your Baseline becomes a chiller system, pump energy will probably become similar.</span></p>
<p><span style="font-size:11.0pt;font-family:Symbol;color:#1F497D"><span>·<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;color:#1F497D">Check fan total pressure drop for each system since your fan power is significantly larger in the Proposed system.</span></p>
<p><span style="font-size:11.0pt;font-family:Symbol;color:#1F497D"><span>·<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;color:#1F497D">In the US, it is common to apply occupancy sensors on a LEED project and ASHRAE 90.1 allows a 10% power reduction when these are used. You are not taking advantage of that and may want to do so.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><p class="MsoNormal" align="center" style="text-align:center"><b><span style="font-size:13.5pt;color:#1F497D">The Building Performance Team<br>
</span></b><b><span style="font-size:11.0pt;color:#1F497D">James V. Dirkes II, P.E., BEMP , LEED AP<br></span></b><span style="font-size:11.0pt;color:#1F497D">1631 Acacia Drive NW<br>Grand Rapids, MI 49504<br><a href="tel:616%20450%208653" value="+16164508653" target="_blank">616 450 8653</a></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"> </span></p><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in"><p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:10.0pt">From:</span></b><span style="font-size:10.0pt"> <a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a> [mailto:<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Marcus<br>
<b>Sent:</b> Monday, May 23, 2011 4:24 PM<br><b>To:</b> <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a><br><b>Subject:</b> [Bldg-sim] PTHP Baseline outperforming VAV</span></p>
</div><div><div></div><div class="h5"><p class="MsoNormal" style="margin-left:.5in"> </p><p class="MsoNormal" style="margin-right:0in;margin-bottom:12.0pt;margin-left:.5in">Hi all, <br><br>Having some difficulty in an App. G model for a 6-floor 14,000 m2 GFA Hotel in zone 1B (Abu Dhabi). Assuming standard design for each, should a proposed VAV system out-perform window AC units (the baseline)? <br>
<br>Proposed: <br>VAV with 2 Air-cooled centrifugal chillers, chiller COP = 3.1 (2.8 if condenser fan energy included)<br>Envelope - Better windows decrease heating demand by 8% rest of envelope is minimum required for compliance<br>
<br>Baseline: <br>System Packaged terminal heat pump, COP = 3.52<br><br>Using Energyplus v6.0 the results are;<br><br><span style="font-family:"Courier New"">Site Energy in End Uses BL Proposed COP5<br>
MWh MWh MWh<br> Space Cooling 747.5 1052.0 715.6 <br> Heat Rejection 0.0 0.0 0.0 <br> Space Heating 1.3 0.1 0.1 <br>
Pumps 0.0 60.0 60.0 <br> Fans - Interior 42.2 137.7 137.7 <br> Fans - Car park 0.0 0.0 0.0 <br> Interior Lighting 530.5 530.5 530.5 <br>
Exterior Lighting 0.0 0.0 0.0 <br> Service Water Heating 0.0 0.0 0.0 <br> Receptacle/Process Equipment 146.3 146.3 146.3 <br> Data Centre Equipment 0.0 0.0 0.0 <br>
Elevators and Escalators 0.0 0.0 0.0 <br> Total Site Energy 1467.9 1926.6 1590.2</span><br><br>I have the energy for the baseline, the proposed with COP = 3.1, and then trying COP = 5. It seems that even if we drastically increase the COP of the chiller plant in the proposed VAV system, we still can't get any energy savings. Is this realistic, an artifact of the simulation, or just an error on my part? <br>
<br>Any guidance would be appreciated, <br><br>Marcus<br>-- <br>Marcus Jones, LEED AP, M.Sc. <br><i>Freelance energy consultant</i><br><i>Vienna, Austria</i><br><br></p></div></div></div></div><br>_______________________________________________<br>
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