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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#0070C0'>Rob,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#0070C0'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#0070C0'>I have never read specific conditions of when to use one over
the other however typically the conditions used are dictated by the type of
building. In my experience buildings with low tolerances for temperature change
use the 99.6%/0.4%. These buildings would include hospitals, laboratories,
R&D etc. Buildings with a high level of tolerance will use 99%/1%. These
buildings are typically office buildings, higher education, retail etc.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#0070C0'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#0070C0'>In the past six months I have seen a huge change in design
conditions. The latest owner has specified design conditions of ASHRAE 99%/1%
with Summer indoor of 78 deg F/50%RH and Winter indoor of 68 deg F. However,
they want the thermostat set point to be 73 deg F year round.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#0070C0'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Georgia","serif";
color:#0070C0'>Seth Spangler, LEED® AP <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Georgia","serif";color:#0070C0'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Georgia","serif";
color:#0070C0'>RMF Engineering, Inc <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Georgia","serif";
color:#0070C0'>Ph: (843) 971-9639 ext:1497</span><span style='color:#0070C0'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Georgia","serif";
color:#0070C0'>Fax: (843) 971-9641 <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Georgia","serif";
color:#0070C0'>sspangle@rmf.com</span><span style='font-size:11.0pt;font-family:
"Calibri","sans-serif";color:#0070C0'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#0070C0'><o:p> </o:p></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"'> bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <b>On Behalf Of </b>Rob Hudson<br>
<b>Sent:</b> Tuesday, June 22, 2010 11:15 AM<br>
<b>To:</b> bldg-sim@lists.onebuilding.org<br>
<b>Subject:</b> [Bldg-sim] ASHRAE question<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I was asked what influences an engineers decision over
design conditions, and after looking for some textural support in the books, i
could not find anything to give guidance over when to use 0.4/1/2 or 99/99.6 %
design conditions. Does anyone know if this text exists in the ASHRAE
books and if so which chapter? I also looked into ASHRAE 90.1, but that
only addresses efficiencies of equipment and not the design conditions/capacity
calculations.<br>
<br>
Thanks in advance,<br clear=all>
<br>
-- <br>
Rob Hudson<o:p></o:p></p>
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