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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Very interesting. It hadn’t occurred to me that you might
bump into the dehumidification set-point during night setback (then again, a
lot of things haven’t occurred to me). But it seems to need to be under a
set of just right conditions. When could the space cool down fast enough at
night, while still having a high enough humidity level to trigger
dehumidification? <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I don’t think this would occur during the winter. Let’s
assume this building is up north where shell losses can add up and cool a space
down relatively fast during winter. Even if you’re humidifying to 40% at
70F during the day (which he’s not) and dropping to 60F at night, you’re
only hitting 57% RH, assuming constant absolute humidity. For a lab, the make
up air (which has a low absolute humidity because of the low ambient temperatures)
would probably dry out the space before the indoor temp hits a point low enough
to set of dehumidification. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>So the other possibility I see (which is what Fred described, I
believe) is that during some nights the make up air is bringing in moist, cool
air, and the system isn’t tempering it because the zone is satisfied. So
this extra air cools down the space and drags up the RH, triggering a dehumidification
mode that would be unnecessary at 70F indoor set-point. But if this was the
case, wouldn’t your heating energy go down more than slightly due to the
reduced ventilating loads?<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>What am I missing here? How large are those internal latent loads
(seems to be a wild card to me)? I’m curious as to whether you’ve
solved this one Rob. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Cheers,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Eric<o:p></o:p></span></p>
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<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
0in;margin-left:.5in;margin-bottom:.0001pt'><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"'> equest-users-bounces@lists.onebuilding.org
[mailto:equest-users-bounces@lists.onebuilding.org] <b>On Behalf Of </b>Fred
Porter<br>
<b>Sent:</b> Wednesday, May 19, 2010 7:07 PM<br>
<b>To:</b> Rob Hudson<br>
<b>Cc:</b> equest-users@lists.onebuilding.org<br>
<b>Subject:</b> Re: [Equest-users] T-Stat is acting Screwy<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p>
<div>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
0in;margin-left:.5in;margin-bottom:.0001pt'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>Rob, <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
0in;margin-left:.5in;margin-bottom:.0001pt'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>I'm a little unclear about statements like
"I looked at my SAT and it is controlled by a reset schedule." Does
this mean that the reset schedule a) came from "The Wizard," b)
actual AHU sequences, c) a departed modeler (you know who you
are!) or some other source. This is important and should be
checked. <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
0in;margin-left:.5in;margin-bottom:.0001pt'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
0in;margin-left:.5in;margin-bottom:.0001pt'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>What's happening to increase the cooling coil
load is that at certain hours the baseline reset SAT (e.g. 60F high
RH) is not providing 53% RH indoor conditions at reduced 65F zone
temp even though it did at 70F. So DOE-2.2 resets down to the
MIN-SUPPLY-T (probably 55F) in the "parametric" with the
setback zone Ts. Thus, coil load shoots up at those hours, and there are no
hours where the cooling load is decreased by changing, even increasing, the
zone Ts.<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
0in;margin-left:.5in;margin-bottom:.0001pt'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
0in;margin-left:.5in;margin-bottom:.0001pt'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>The lab users need to decide whether the
appropriate upper RH limit is really 53%. It if can be increased, then you
can save money by increasing it, and instituting setbacks. And
perhaps a setpoint decrease to only 67-68F <em><span
style='font-family:"Arial","sans-serif"'>might</span></em> give better results
in reality and model land. But it sounds like you are unsure of some of
the model and the lab requirements. If this is the case I would be very
careful about making recommendations to lab owners and users along the lines of
"....reduce zone heating setpoint to 60F," because if they could just
do that, they might not spend millions of dollars on Phoenix valves
to control VAV. You need to model the correct SATs, and only
reasonable zone conditions. <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
0in;margin-left:.5in;margin-bottom:.0001pt'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
0in;margin-left:.5in;margin-bottom:.0001pt'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>Fred Porter<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
0in;margin-left:.5in;margin-bottom:.0001pt'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
0in;margin-left:.5in;margin-bottom:.0001pt'><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'><br>
>>> On 5/19/2010 at 1:21 PM, in message <AANLkTinV1_p5XWNJrIiRwocYPovZQVPlvHc1Uzu0DixR@mail.gmail.com>,
Rob Hudson <rdh4176@gmail.com> wrote:<o:p></o:p></span></p>
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<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
12.0pt;margin-left:0in'>I'm trying to wrap my head around this the best i
can. <br>
<br>
I looked at my SAT and it is controlled by a reset schedule. the temperature
of the space never reaches anything above about 72 deg, which makes me think
that what you are saying is very true and the heating t-stat schedule is in
control all the time. <br>
<br>
So can you tell me what it is that i can do to fix this? <o:p></o:p></p>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'>On Wed, May 19,
2010 at 2:52 PM, Fred Porter <<a href="mailto:FPorter@archenergy.com">FPorter@archenergy.com</a>>
wrote:<o:p></o:p></p>
<div style='margin-left:3.0pt;margin-top:3.0pt;margin-right:3.0pt;margin-bottom:
.75pt'>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Rob,<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'>OK, I can't resist
a bit of lunchtime "Stump the Chump." First I'd say verify the
setpoint change in the runs is actually working by examining SS-O for the
baseline and parametric run. But I'll assume it is, and offer my explanation.<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'>One piece that is
left out in all this is the SAT control.... very important for a CV-reheat
application. And LOCATION! <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'>My bet is that your
SAT is resetting down at night based on hitting the upper RH limits during
the setback scenario. This is why the CHW load increases. This is also why HW
savings might not be as great as expected. <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Holding all else
the same, the hourly temperature in a lab zone will with minimal internal
gains as described will follow the heating setpoint down; the cooling
setpoint will not be in control. Generally this will lead to high internal <i>relative</i>
humidity (which is why this setback is only done carefully and to a limited
extent in labs) from the OA for many hours, even if internal latent gains are
nil. If the "baseline" model has any SAT reset, the MAX-HUMIDITY
resets the hourly SAT back down to the MIN-SUPPLY-T when the model zone RH
exceeds the RH setpoint, in this case a relatively low 53%. This increases in
frequency as the zone temperature decreases.<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#888888'>Fred
Porter<o:p></o:p></span></p>
</div>
<div>
<div>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'><br>
>>> On 5/19/2010 at 9:24 AM, in message <<a
href="mailto:AANLkTinsmv-lXFuk3A65lvU2asMT_VshFXVOYiSk6xwB@mail.gmail.com"
target="_blank">AANLkTinsmv-lXFuk3A65lvU2asMT_VshFXVOYiSk6xwB@mail.gmail.com</a>>,
Rob Hudson <<a href="mailto:rdh4176@gmail.com" target="_blank">rdh4176@gmail.com</a>>
wrote:<o:p></o:p></span></p>
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<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;
margin-bottom:12.0pt;margin-left:0in'>Thanks for your thoughts and here is
your answers:<br>
<br>
1) yes, but there is no night set back time.<br>
2) everything is 100% oa and constant volume 24/7/365<br>
3)no exhaust heat recovery, and steam preheat. the thermostat is set for 70
- 73 heating and cooling and the set back is to 60 and 80 at night for my
parametric run.<br>
4) the cooling comes from a central chilled water plant for the entire
campus, and i just created a chilled water loop, added a meter and a pump
and it seems to be running happily.<br>
5) the fans run all the time, day and night<br>
6) I do have internal loads with latent heat, and it cycles down at night
to almost nothing. These loads are currently the same for the model and the
parametric run.<br>
7) i have set humidity levels to 20% and 53%, which also do not change with
my parametric run. <br>
<br>
hope this give you enough information.<br>
<br>
thanks again<o:p></o:p></p>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'>On Wed, May 19,
2010 at 11:13 AM, David Bastow <<a
href="mailto:dbastow@mcclure-engineering.com" target="_blank">dbastow@mcclure-engineering.com</a>>
wrote:<o:p></o:p></p>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>Rob,</span><o:p></o:p></p>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>I have
a number of questions:</span><o:p></o:p></p>
<ol start=1 type=1>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>Do
you have many lab hoods? And are exhaust and make-up air revised for
the lab hoods at the night set back time?</span><o:p></o:p></li>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>What
is the percent of outside air to the lab? Does this percentage change
during the night set back time?</span><o:p></o:p></li>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>Do
you have a pre-heat or exhaust heat recovery and pre-cooling on your
make-up air? What is the temperature setting of this pre-heat or heat
recovery and pre-cooling? Does the temperature settings on these
change at the night set back time?</span><o:p></o:p></li>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>Do
you utilize an air or water side economizer for 1st stage cooling?
Does this use change any at night set back time?</span><o:p></o:p></li>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>Does
the fan run continuously day and night? Have you ran models with the
fan running continuously, and with fan cycling based on demand at
night and off completely at night, to see how the results compare?</span><o:p></o:p></li>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>Do
you have a internal load watts per square foot and latent load on the
space from interior lighting and equipment? Do these loads change at
the night set back time?</span><o:p></o:p></li>
<li class=MsoNormal style='mso-list:l0 level1 lfo1'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>Are
you adding humidification or dehumidifying the space based on some
humidity settings? Does the humidity settings change during the night
set back time?</span><o:p></o:p></li>
</ol>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>One of
these things is probably causing the increased chilled water cooling load.
Often if you have high internal loads, even at night, then changes to the
fan cycling and the amount of outside air brought in at night, will
increase the chilled water cooling load. I would review all of these areas
and run various test models to see how they each affect your energy usage
when modified.</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'>Our
firm just completed modeling some very large lab facilities with more than
55 exhaust hoods in the building, with high internal loads 24/7 and 100%
outside air. As long as the models are set up correctly they are normally
right. It takes some real design and thermal dynamic thought and often may
models to really get your mind right with what is truly going on with the
facility. Its important to keep an open mind to what is going on. Having
been doing computer hourly modeling for over 17 years, it is often easy to
think you have a handle on what is going on with the building, but it is
important to keep an open mind and investigate all the different avenues
that you can think of until figure out what is going on. I have 99% of the
time that I have blamed the screwy program having problems that I have
found that I just didn't look at all the different angles enough.</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><b><i><span
style='font-size:24.0pt;font-family:"Bradley Hand ITC";color:blue'>David A.
Bastow </span></i></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'><o:p></o:p></span></p>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><b><i><span
style='font-size:10.0pt;font-family:"Rockwell Extra Bold","serif";
color:blue'>McClure Engineering, Inc. </span></i></b><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:blue'><o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><o:p> </o:p></p>
</div>
<div class=MsoNormal align=center style='margin:0in;margin-bottom:.0001pt;
text-align:center'>
<hr size=2 width="100%" align=center>
</div>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;
margin-bottom:12.0pt;margin-left:0in'><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"'> <a
href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a>
[mailto:<a href="mailto:equest-users-bounces@lists.onebuilding.org"
target="_blank">equest-users-bounces@lists.onebuilding.org</a>] <b>On
Behalf Of </b>Rob Hudson<br>
<b>Sent:</b> Wednesday, May 19, 2010 7:46 AM<br>
<b>To:</b> <a href="mailto:equest-users@lists.onebuilding.org"
target="_blank">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> [Equest-users] T-Stat is acting Screwy</span><o:p></o:p></p>
<div>
<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'>I have a lab
space that is kept between 73 and 70 degrees all year long. One of my
parametric runs has the cooling and heating T-stat schedules changing to
have night time setbacks to 80 and 60, respectively. When i use these, i
get more energy spent overall. specifically, i have a chilled water meter,
steam meter, electric meter and hot water meter to monitor everything. The
chilled water increases while the others slightly decrease when i use the
set back schedules. Any ideas?<br clear=all>
<br>
-- <br>
Rob Hudson<o:p></o:p></p>
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<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><br>
<br clear=all>
<br>
-- <br>
Rob Hudson<o:p></o:p></p>
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<p class=MsoNormal style='margin:0in;margin-bottom:.0001pt'><br>
<br clear=all>
<br>
-- <br>
Rob Hudson<o:p></o:p></p>
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<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
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