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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi Marcus,<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'>I agree with your selection of PTHP for the baseline, since your project is a hotel, which is specifically listed in the notes to Table G3.1.1A as being a residential building type.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I am not surprised that you are showing an energy penalty versus an ASHRAE 90.1 PTHP – the cooling and fan energy is relatively low for those units.<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'>As James said, make sure you are accurately modeling your fan and pumping energy in the proposed system. Unfortunately, there are no pressure drop adjustment allowances for Systems 1 & 2.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The maximum allowable SHGC (0.25) is already pretty low for Abu Dhabi, so your “better windows” might not have a lower SHGC than the value required for the baseline, and you will not get a solar load reduction in the proposed model.<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'>Since your baseline cooling efficiency is dependent on the system capacities, make sure you are not using too large of a baseline cooling COP. (It should actually be calculated separately for each baseline system.) Using the efficiency equation from Table 6.8.1D, assuming 400 cfm/ton air flow rate and removing the fan power energy from the efficiency, I calculate COP = 2.94 for a 15,000 Btu/hr unit (for example). There is a separate heating COP but your heating load is negligible per your report below.<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'>Regards,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Bill<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'><img width=496 height=123 id="Picture_x0020_1" src="cid:image001.jpg@01CC19EB.14B1FE40" alt="Signature in jpg form"><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><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><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>Cheney<br><b>Sent:</b> Monday, May 23, 2011 9:55 PM<br><b>To:</b> James V Dirkes II, PE<br><b>Cc:</b> bldg-sim@lists.onebuilding.org<br><b>Subject:</b> Re: [Bldg-sim] PTHP Baseline outperforming VAV<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Hi Marcus, <o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>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. <o:p></o:p></p></div><div><p class=MsoNormal> <br clear=all><o:p></o:p></p><div><p class=MsoNormal><span style='font-family:"Comic Sans MS"'>Regards, </span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Comic Sans MS"'>Cheney</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Comic Sans MS"'>LinkedIN @ </span><a href="http://ca.linkedin.com/pub/yu-cheney-chen/27/637/72b" target="_blank"><span style='font-family:"Comic Sans MS"'>http://ca.linkedin.com/pub/yu-cheney-chen/27/637/72b</span></a><span style='font-family:"Comic Sans MS"'> </span><o:p></o:p></p></div><p class=MsoNormal style='margin-bottom:12.0pt'><br><br><o:p></o:p></p><div><p class=MsoNormal>On Mon, May 23, 2011 at 3:18 PM, James V Dirkes II, PE <<a href="mailto:jim@buildingperformanceteam.com">jim@buildingperformanceteam.com</a>> wrote:<o:p></o:p></p><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;color:#1F497D'>Dear Marcus,</span><o:p></o:p></p><p><span style='font-size:11.0pt;font-family:Symbol;color:#1F497D'>·</span><span style='font-size:7.0pt;color:#1F497D'> </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><o:p></o:p></p><p><span style='font-size:11.0pt;font-family:Symbol;color:#1F497D'>·</span><span style='font-size:7.0pt;color:#1F497D'> </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><o:p></o:p></p><p><span style='font-size:11.0pt;font-family:Symbol;color:#1F497D'>·</span><span style='font-size:7.0pt;color:#1F497D'> </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><o:p></o:p></p><p><span style='font-size:11.0pt;font-family:Symbol;color:#1F497D'>·</span><span style='font-size:7.0pt;color:#1F497D'> </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><o:p></o:p></p><p><span style='font-size:11.0pt;font-family:Symbol;color:#1F497D'>·</span><span style='font-size:7.0pt;color:#1F497D'> </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><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal align=center style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;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" target="_blank">616 450 8653</a></span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;color:#1F497D'> </span><o:p></o:p></p><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;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><o:p></o:p></p></div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:.5in'> <o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;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><o:p></o:p></p></div></div></div></div><p class=MsoNormal style='margin-bottom:12.0pt'><br>_______________________________________________<br>Bldg-sim mailing list<br><a href="http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org" target="_blank">http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org</a><br>To unsubscribe from this mailing list send a blank message to <a href="mailto:BLDG-SIM-UNSUBSCRIBE@ONEBUILDING.ORG">BLDG-SIM-UNSUBSCRIBE@ONEBUILDING.ORG</a><o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>