<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:arial, helvetica, sans-serif;font-size:10pt"><div style="color: black; font-family: arial, helvetica, sans-serif; font-size: 10pt; "></div><div><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;">My first guess would be to look into the residential systems further. Read the </span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="3"><span class="Apple-style-span" style="font-size: 13px;">topic</span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;"> on this </span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="3"><span class="Apple-style-span" style="font-size: 13px;">particular</span></font><font
class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;"> system in the help file. As far as I can remember, this system will </span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="3"><span class="Apple-style-span" style="font-size: 13px;">automatically</span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;">, reduce the </span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="3"><span class="Apple-style-span" style="font-size: 13px; ">set point</span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;"> temperatures, and flow rates (or </span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif"
size="3"><span class="Apple-style-span" style="font-size: 13px;">something</span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;"> similar) based on the occupancy. This can provide significant savings, </span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="3"><span class="Apple-style-span" style="font-size: 13px; ">especially</span></font><font class="Apple-style-span" face="arial, helvetica, sans-serif" size="4"><span class="Apple-style-span" style="font-size: 10pt;"> if you have a low occupancy rate. So I would start from there. </span></font><span class="Apple-style-span" style="font-family: arial, helvetica, sans-serif; font-size: 13px; ">If you attach you input file, we (the online community) can take a look at it hopefully find the true issue. </span></div><div style="color: black;
font-family: arial, helvetica, sans-serif; font-size: 10pt; "><div style="font-family:arial, helvetica, sans-serif;font-size:10pt"><br></div><div style="font-family:arial, helvetica, sans-serif;font-size:10pt">-Eddie</div><div style="font-family:arial, helvetica, sans-serif;font-size:10pt"><br><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><font size="2" face="Tahoma"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> Robert Stephenson <rstephenson@southface.org><br><b><span style="font-weight: bold;">To:</span></b> equest-users@lists.onebuilding.org<br><b><span style="font-weight: bold;">Sent:</span></b> Mon, November 8, 2010 2:25:18 PM<br><b><span style="font-weight: bold;">Subject:</span></b> [Equest-users] Excessive Heating Savings<br></font><br>
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<p class="MsoNormal">Hello All,</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I am having some issues with modeling the heating and
cooling systems in mid-rise multifamily buildings. I have a number of these
projects and they all use similar and fairly simple systems, a single split
system heat pump serving each dwelling unit. When modeling these projects I
have followed the guidelines from Appendix G with additional guidance from the
ENERGY STAR High Rise program’s simulation guidelines. No matter the
project location, I am getting heating savings that seem very out of whack with
the upgrades made in the proposed design (higher efficiency HVAC, better
windows, upgraded insulation, etc.), the particular model I am looking at now
has heating savings over 90%.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">An outline of my system inputs follows. I developed this
approach based on the guidelines discussed above, past listserv discussions,
and the input of other local energy modelers.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><u>Proposed Model</u></p>
<p class="MsoListParagraph" style=""><span style="font-family:Symbol;"><span style="">·<span style="font:7.0pt "Times New Roman";">
</span></span></span>System type set to Residential System 2</p>
<p class="MsoListParagraph" style=""><span style="font-family:Symbol;"><span style="">·<span style="font:7.0pt "Times New Roman";">
</span></span></span>System capacities based on actual design</p>
<p class="MsoListParagraph" style=""><span style="font-family:Symbol;"><span style="">·<span style="font:7.0pt "Times New Roman";">
</span></span></span>Electric Input Ratios</p>
<p class="MsoListParagraph" style="margin-left:1.0in;"><span style="font-family:"Courier New";"><span style="">o<span style="font:7.0pt "Times New Roman";">
</span></span></span>Cooling</p>
<p class="MsoListParagraph" style="margin-left:1.0in;">EIR=((1/(SEER*0.778+1.4)-0.012167)/((1/3.413)+0.012167)</p>
<p class="MsoListParagraph" style="margin-left:1.0in;">SEER 14 yields 0.227 CEIR</p>
<p class="MsoListParagraph" style="margin-left:1.0in;"><span style="font-family:"Courier New";"><span style="">o<span style="font:7.0pt "Times New Roman";">
</span></span></span>Heating</p>
<p class="MsoListParagraph" style="margin-left:1.0in;">EIR= (1/((HSPF*0.28+1.13)*3.412)-0.012167)/((1/3.412)-0.012167)</p>
<p class="MsoListParagraph" style="margin-left:1.0in;">HSPF 7.7 yields 0.274 HEIR</p>
<p class="MsoListParagraph" style=""><span style="font-family:Symbol;"><span style="">·<span style="font:7.0pt "Times New Roman";">
</span></span></span>Fan Power set to zero given that fan power is
accounted for in SEER and HSPF efficiency ratings</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><u>Baseline Model</u></p>
<p class="MsoListParagraph" style=""><span style="font-family:Symbol;"><span style="">·<span style="font:7.0pt "Times New Roman";">
</span></span></span>System type set to PTHP, Packaged Terminal AC
with heat pump heating, per Appendix G and ENERGY STAR simulation guidelines.</p>
<p class="MsoListParagraph" style=""><span style="font-family:Symbol;"><span style="">·<span style="font:7.0pt "Times New Roman";">
</span></span></span>System capacities set by equest, 15% oversized
for cooling and 25% for heating</p>
<p class="MsoListParagraph" style=""><span style="font-family:Symbol;"><span style="">·<span style="font:7.0pt "Times New Roman";">
</span></span></span>Electric Input Ratios</p>
<p class="MsoListParagraph" style="margin-left:1.0in;"><span style="font-family:"Courier New";"><span style="">o<span style="font:7.0pt "Times New Roman";">
</span></span></span>Cooling</p>
<p class="MsoListParagraph" style="margin-left:1.0in;">EER per 90.1: EER = 12.3-(0.213*Cap/1000)</p>
<p class="MsoListParagraph" style="margin-left:1.0in;">Capacity set to 15,000
Btu/hr yields 9.1 EER</p>
<p class="MsoListParagraph" style="margin-left:1.0in;">EIR= (1/EER-0.012167)/((1/3.413)+
0.012167)</p>
<p class="MsoListParagraph" style="margin-left:1.0in;">Yields 0.32 CEIR</p>
<p class="MsoListParagraph" style="margin-left:1.0in;"><span style="font-family:"Courier New";"><span style="">o<span style="font:7.0pt "Times New Roman";">
</span></span></span>Heating</p>
<p class="MsoListParagraph" style="margin-left:1.0in;">EIR= 3.2-(0.026*Cap/1000)</p>
<p class="MsoListParagraph" style="margin-left:1.0in;">Capacity set to 15,000
Btu/hr yields 2.81 COP</p>
<p class="MsoListParagraph" style="margin-left:1.0in;">EIR=1/COP</p>
<p class="MsoListParagraph" style="margin-left:1.0in;">Yields 0.356 HEIR</p>
<p class="MsoListParagraph" style=""><span style="font-family:Symbol;"><span style="">·<span style="font:7.0pt "Times New Roman";">
</span></span></span>Fan Power set to zero given that these are
packaged units</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Outside air rates, infiltration levels, and supplemental
heating are set identically in both models. The only other issue of note is
that the proposed design has unit heaters (electric resistance heat) in the
stairwells, which I have modeled as PTHPs in the baseline design with heating
only. I would assume this would be a loss for the proposed design, though
negligible, given the increased efficiency of the PTHPs versus electric
resistance, but I’m not seeing that reflected in the results.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">If anyone has advice on what I might be missing I would
appreciate it. Tips on places to check myself in the .sim file would also be
great.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Thanks in advance,</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;color:gray;">Robert Stephenson,
LEED AP </span></b></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;color:gray;">Project
Manager, Residential Green Building Services</span></b></p>
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404-604-3589</span></b><span style="font-size:12.0pt;font-family:"serif";color:#1F497D;"></span></p>
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font-size:10.0pt;color:gray;">Fax: 404-872-5009</span></b><span style="font-size:10.0pt;color:gray;"><br>
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