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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Hi Dan,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I would clarify two things. First is
that the load calculations are done, or should be done, for the design condition,
not the worst possible condition plus safety factor. For cooling that normally
means the ASHRAE 97-1/2% condition; for heating, the 2-1/2% condition. Some
programs list adjustments as safety factors, but there is really a higher
purpose. One is a morning warm-up factor that allows night setback energy
savings to be realistically achievable. Similarly, a cool-down factor can
be applied to the cooling load and comes into play often on Monday morning when
the system has been off over the weekend and the building mass has gotten quite
warm. If you can’t cool it down, then you can’t save as much energy
by letting it get or stay warm for as long prior to occupancy. The
warm-up and cool-down factors are largely a function of the space mass (the greater
the mass, the larger the factor needed). There is also the possibility of
either adding capacity for future building or process load additions or
designing for the ability to add the capacity in the future. It is best
to do that in a modular way the does not penalize efficiency until the future
load is on-line.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Second is that load programs do have schedules
for people, lighting, appliances, and power equipment. It is proper to
set those realistically for the highest anticipated conditions, but not
higher. If set higher, or at 100%, then the result will have compounding
additional capacity (safety factors multiplied upon each other resulting in
grossly over-sized systems). Heating is traditionally treated differently
in that internal loads are normally not left on for the design condition.
It is possible to turn off all lights and internal gains during a heating
requirement. Cooling is a little different in that some loads are simply
never all on at the same time. People move throughout the building and
they also come and go, so diversity factors are also appropriate.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I would expect, or at least want, a
program that does both load calculation and energy modeling to be able to
account for morning warm-up and cool-down (including after a power outage) by
sizing the systems to have sufficient reserve capacity to recover in a
reasonable period of time (and have that time adjustable). It would need
to consider building mass, and look at setback/setup differentials vs. recovery
time and reserve capacity.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 color=navy face="Monotype Corsiva"><span
style='font-size:12.0pt;font-family:"Monotype Corsiva";color:navy'>Michael
Haughey,P.E., LEED AP<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=navy face="Monotype Corsiva"><span
style='font-size:12.0pt;font-family:"Monotype Corsiva";color:navy'>Silvertip
Integrated Engineering Consultants</span></font><font color=navy><span
style='color:navy'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=navy face="Monotype Corsiva"><span
style='font-size:12.0pt;font-family:"Monotype Corsiva";color:navy'>303-650-1080</span></font><font
color=navy><span style='color:navy'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=navy face="Monotype Corsiva"><span
style='font-size:12.0pt;font-family:"Monotype Corsiva";color:navy'>mhaughey@earthlink.net</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Dan Katzenberger<br>
<b><span style='font-weight:bold'>Sent:</span></b> Friday, January 25, 2008
11:09 PM<br>
<b><span style='font-weight:bold'>To:</span></b> bldg-sim@lists.onebuilding.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [Bldg-sim] Load Calcs
with Energy Simulation Software</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Jonathan,</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>There are several differences between load calculation and
energy simulation programs, some of which others have mentioned. Some
other differences include:</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>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.</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>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.</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>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.</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>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.</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>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.</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>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.</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Dan</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Daniel A. Katzenberger, P.E., CEM, LEED-AP</span></font> <font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'><o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Principal & Certified <st1:place w:st="on"><st1:PlaceName
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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> <o:p></o:p></span></font></p>
<p class=MsoNormal><strong><b><font size=2 face="Maiandra GD"><span
style='font-size:10.0pt;font-family:"Maiandra GD"'>Engineering, Energy, and the
Environment, LLC</span></font></b></strong><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face="Maiandra GD"><span style='font-size:10.0pt;
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<p class=MsoNormal><st1:address w:st="on"><st1:Street w:st="on"><font size=1
face=Arial><span style='font-size:7.5pt;font-family:Arial'>420 North 5th
Street, Suite 305</span></font></st1:Street><font size=1 face=Arial><span
style='font-size:7.5pt;font-family:Arial'>, <st1:City w:st="on">Minneapolis</st1:City>,
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Jonathan Curtin<br>
<b><span style='font-weight:bold'>Sent:</span></b> Friday, January 25, 2008
3:25 PM</span></font><font size=2 color=blue face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:blue'> </span></font><o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma'> <br>
<b><span style='font-weight:bold'>To:</span></b> bldg-sim@lists.onebuilding.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> [Bldg-sim] Load Calcs
with Energy Simulation Software</span></font><o:p></o:p></p>
<div>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Hello All,</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>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?</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Thanks,</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><b><font size=2 color="#4d4d4d" face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:#4D4D4D;font-weight:bold'>Jonathan
Curtin EIT, LEED AP</span></font></b><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=4 color="#4d4d4d" face=Arial><span
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title="http://www.wylieassociates.com/">www.wylieassociates.com</a></span></font><o:p></o:p></p>
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