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<p class=MsoNormal><span style='color:#1F497D'>I find that ERVs use more energy
when the Make-up Air Temp Ctrl is specified as “Float”. In other
words, there is no temperature control of the air leaving the ERV. For an
enthalpy wheel, choose “Modulate HX”. This allows the rotational speed
of the wheel to vary in order to maintain a particular leaving air temperature.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<div>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Kelsey Van Tassel</span></b><b><span style='font-size:12.0pt;
font-family:"Times New Roman","serif";color:#000066'><o:p></o:p></span></b></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Mechanical Engineer | <a href="mailto:kvantassel@sustaineng.com">kvantassel@sustaineng.com</a></span><span
style='font-size:12.0pt;font-family:"Times New Roman","serif";color:#000066'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>608.836.4488 ext. 20 | Fax: 608.836.4477</span><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p></o:p></span></p>
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color:#000066'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Sustainable Engineering Group</span><span style='font-size:12.0pt;
font-family:"Times New Roman","serif";color:#000066'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>901 Deming Way, Suite 201</span><span style='font-size:10.0pt;
font-family:"Arial","sans-serif";color:black'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Madison, WI 53717<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'><a href="http://www.sustaineng.com/">www.sustaineng.com</a><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"'>
equest-users-bounces@lists.onebuilding.org
[mailto:equest-users-bounces@lists.onebuilding.org] <b>On Behalf Of </b>Fleming,
Joe<br>
<b>Sent:</b> Thursday, December 09, 2010 2:12 PM<br>
<b>To:</b> Daniel Knapp; equest-users@lists.onebuilding.org<br>
<b>Subject:</b> Re: [Equest-users] ERV in Ottawa<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoPlainText>I have come across this a lot in eQuest, and the solution
for me is usually to only run the ERV in cooling mode, because I am usually in
a mostly cooling climate. <o:p></o:p></p>
<p class=MsoPlainText>I am not sure exactly how eQuest handles the ERV controls
under "Operating Mode:", but it does say something in the help file
that leads me to believe choosing heat/cool is a bad idea for an operating
mode... <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><i>"OA-HEAT/COOL
the default for enthalpy ERVs, indicates that the ERV will operate whenever the
absolute value of the differential between the outdoor air and the exhaust
exceeds the specified differential."<o:p></o:p></i></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><img border=0 width=632 height=130 id="Picture_x0020_1"
src="cid:image001.png@01CB97AE.8416EDF0"><o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>The difference between OA cooling only or OA heating only
and OA heat/cool is the term "absolute value". If the
conditions are such that the absolute value between the exhaust and outdoor
airflow is less than 5 degrees the ERV is off. If it is greater than 5
degrees the ERV comes on. <u>So the entire period where you are in
cooling mode but it is less than 70 degrees outside, (assuming a 75 degree
space temp, abs|69-75| = +6, the ERV is adding to your cooling load and is
hurting your cause, because we chose OA heat/cool.<o:p></o:p></u></p>
<p class=MsoPlainText> <o:p></o:p></p>
<p class=MsoPlainText>If there were a way in eQuest to use an ERV in heat/cool
mode but eliminate the absolute value part and make it +5 for cooling and -5
for heating, instead of Del_T > abs|OA-EA| then that would allow the ERV's
to operate perfectly and operate in the same fashion as the standard ERV
sequence in the field. <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Does anyone know if this is correct, or if eQuest treats
the control sequence different from what is described above?<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Joe Fleming<o:p></o:p></p>
<p class=MsoPlainText>E.I., LEED AP BD+C, BEMP<o:p></o:p></p>
<p class=MsoPlainText>Mechanical Engineer I<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>TLC Engineering for Architecture<o:p></o:p></p>
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<p class=MsoPlainText>direct:Â <o:p></o:p></p>
<p class=MsoPlainText>954-418-4591<o:p></o:p></p>
<p class=MsoPlainText>website:Â <o:p></o:p></p>
<p class=MsoPlainText>www.tlc-engineers.com<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>-----Original Message-----<br>
From: equest-users-bounces@lists.onebuilding.org
[mailto:equest-users-bounces@lists.onebuilding.org] On Behalf Of Daniel Knapp<br>
Sent: Thursday, December 09, 2010 12:56 PM<br>
To: equest-users@lists.onebuilding.org<br>
Subject: [Equest-users] ERV in Ottawa<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Hello,<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>I've been trying to understand how ERV works because I am
finding the energy savings to be somewhat less than I had expected.
Ottawa has a very cold climate in the winter and a warm, humid climate in the
summer and I would expect enthalpy wheels to be a very good energy saving
strategy. Instead, I am finding that in many cases the building uses more
energy and in the best case scenario (OA exhaust DH, mixed air reset, modulate
HX) on a VAV system saves only 0.15%. I have built a simple box model
with one system in a two-storey office building and tried a number of different
control strategies (see attached tables for results). I have tried a VAV
and a SZ system. The ERV is able to save marginally more energy in the SZ
system, but in neither case are the results what I was expecting.<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>My question is this: are these results to be taken
at face value and believed or is there a better way to model ERVs in a Canadian
climate? It seems very unlikely to me that ERVs cannot be controlled in
such a way as to save significant energy in a climate of extremes. (.inp
file attached as well). <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>With thanks and best wishes,<o:p></o:p></p>
<p class=MsoPlainText>Dan<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>—<o:p></o:p></p>
<p class=MsoPlainText>Daniel Knapp, PhD, LEED® AP O+M<o:p></o:p></p>
<p class=MsoPlainText>danielk@arborus.ca<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Arborus Consulting<o:p></o:p></p>
<p class=MsoPlainText>Energy Strategies for the Built Environment
www.arborus.ca<o:p></o:p></p>
<p class=MsoPlainText>76 Chamberlain Avenue<o:p></o:p></p>
<p class=MsoPlainText>Ottawa, ON, K1S 1V9<o:p></o:p></p>
<p class=MsoPlainText>Phone: (613) 234-7178 ext. 113<o:p></o:p></p>
<p class=MsoPlainText>Fax: (613) 234-0740<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
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