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<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2>Jonathan,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2>There are several differences between load calculation and energy
simulation programs, some of which others have mentioned. Some other
differences include:</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2>Summer load calculations are done at the worst summer design conditions
(outdoor air temperature, outdoor humidity, solar gain, etc.), and all of the
internal gains are assumed to be on 100% (e.g., people, lights, equipment,
etc.). Energy programs use schedules and may not have 100% of the internal
gains on during the peak summer conditions, thereby suggesting smaller equipment
sizes.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2>Winter load calculations are done at the worst winter design conditions
(outdoor air temperature, nighttime, etc.), and the internal gains are all
assumed to be 0% (e.g., no people, no lights, no equipment, etc.). Energy
programs use schedules, and may not have 100% of the people, lights, and
equipment off during peak winter conditions.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2>Some load programs allow the user to add a safety factor to the heating
and cooling loads (not just the equipment size). So the heating/cooling
load in your zone is increased, therefore your air supply cfm is increased, your
AHU is increased in size, your plant size is increased, etc.). I
don't know how to do this directly in any of the energy analysis programs
that I use.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2>Because of these and other differences, I have found that energy modeling
programs will give smaller equipment sizes than do load programs.
Engineers typically error on the side of safety, and therefore they prefer
to size equipment for the worst possible scenarios as described above.
When I was designing building mechanical systems, I would never count on
25% of the lights being on at night when it's -20 degrees F outside so that I
could reduce my boiler size. My loads program would give me a larger
boiler, whereas my energy modeling program would give me a boiler sized as if
the lights will be on. Also, the local TMY2 weather file that I use
for energy modeling doesn't even have -20 degrees F as an outdoor air
temperature, and this is the temperature that many engineers use to design their
heating systems. M loads programs allow the outdoor design conditions to
be input directly.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2>Load programs require much less input than energy programs, and generally
don't require any special knowledge, art, or workarounds. Energy modeling
programs require much more input, require very specialized knowledge and
experience, and always require workarounds and creative inputs (art) to
get the correct results.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2>All that being said, Trane's Trace 700 program does an
acceptable job of being both a loads program and an energy analysis
program, although it does have strengths and weaknesses in both areas. In
Trace, when running loads, you can disable the energy related inputs.
After you are satisfied that you have the correct loads, then you can proceed to
working on the energy parameters and inputs. You can easily switch between
running loads only and loads + energy at any time.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
size=2>Dan</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008>
<DIV dir=ltr align=left><FONT face=Arial size=2><SPAN
class=530213506-18012008><SPAN class=592355206-02012008><SPAN
class=404585617-30112007><SPAN class=993394115-28112007><FONT face=Arial
size=2>Daniel A. Katzenberger, P.E., CEM, LEED-AP</FONT></SPAN><FONT
face="Times New Roman" size=3> </FONT>
<DIV>
<DIV dir=ltr align=left><SPAN class=993394115-28112007><FONT face=Arial><FONT
size=2><SPAN class=446495221-05122007>Principal & </SPAN>Certified Energy
Star Green Building Engineer</FONT></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=993394115-28112007><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=993394115-28112007><FONT face="Maiandra GD"
size=2><STRONG>Engineering, Energy, and the Environment,
LLC</STRONG></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=993394115-28112007><FONT face="Maiandra GD"
size=2>"<FONT color=#00ff00>The Green Group</FONT>"</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=993394115-28112007><FONT face=Arial
size=1>420 North 5th Street, Suite 305, </FONT></SPAN><SPAN
class=993394115-28112007><FONT face=Arial size=1>Minneapolis, MN
55401-1348</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=993394115-28112007><FONT face=Arial
size=1>(612)
327-4210</FONT></SPAN></SPAN></SPAN></DIV></DIV></SPAN></FONT></DIV></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=920493105-26012008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left>
<HR tabIndex=-1>
</DIV>
<DIV dir=ltr align=left><FONT face=Tahoma><FONT size=2><B>From:</B>
bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <B>On Behalf Of </B>Jonathan
Curtin<BR><B>Sent:</B> Friday, January 25, 2008 3:25 PM<SPAN
class=920493105-26012008><FONT face=Arial
color=#0000ff> </FONT></SPAN></FONT></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Tahoma><FONT size=2><SPAN
class=920493105-26012008> </SPAN><BR><B>To:</B>
bldg-sim@lists.onebuilding.org<BR><B>Subject:</B> [Bldg-sim] Load Calcs with
Energy Simulation Software<BR></FONT></FONT><BR></DIV>
<DIV></DIV>
<DIV><SPAN class=434333919-25012008><FONT face=Arial size=2>Hello
All,</FONT></SPAN></DIV>
<DIV><SPAN class=434333919-25012008><FONT face=Arial size=2>Would anyone out
there like to share experiences or precautions in using simulation models
(particularly eQuest, DOE2.1e, EnergyPlus) for load calculations? Any
advantages/disadvantages, tricks, or warnings in using these
simulation models as opposed to dedicated load calculation software like
Elite's CHVAC? Any studies comparing the two?</FONT></SPAN></DIV>
<DIV><SPAN class=434333919-25012008></SPAN><SPAN
class=434333919-25012008></SPAN><SPAN class=434333919-25012008><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=434333919-25012008><FONT face=Arial
size=2>Thanks,</FONT></SPAN></DIV>
<DIV><SPAN class=434333919-25012008><FONT size=2>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt" align=left><B><SPAN
style="FONT-SIZE: 10pt; COLOR: #4d4d4d; FONT-FAMILY: Arial"></SPAN></B> </P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt" align=left><B><SPAN
style="FONT-SIZE: 10pt; COLOR: #4d4d4d; FONT-FAMILY: Arial">Jonathan Curtin EIT,
LEED AP</SPAN></B></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt" align=left><FONT face=Arial
size=1></FONT> </P>
<DIV align=left><SPAN
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style="mso-spacerun: yes"> </SPAN>Y<SPAN style="mso-spacerun: yes">
</SPAN>L<SPAN style="mso-spacerun: yes"> </SPAN>I<SPAN
style="mso-spacerun: yes"> </SPAN>E</SPAN><SPAN
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O N S U L T I<SPAN style="mso-spacerun: yes"> </SPAN>N G<BR>E<SPAN
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</SPAN>N<SPAN style="mso-spacerun: yes"> </SPAN>E<SPAN
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href="http://www.wylieassociates.com/">www.wylieassociates.com</A></SPAN></FONT></DIV></SPAN></DIV></BODY></HTML>