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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><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 width=632 height=130 id="Picture_x0020_1" src="cid:image001.png@01CB97B2.90A7F3D0"><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><p class=MsoPlainText>Your 2030 Challenge Partner<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>800 Fairway Drive, Suite 250<o:p></o:p></p><p class=MsoPlainText>Deerfield Beach, FL 33441-1816<o:p></o:p></p><p class=MsoPlainText><o:p> </o:p></p><p class=MsoPlainText>phone:Â <o:p></o:p></p><p class=MsoPlainText>954-418-9096<o:p></o:p></p><p class=MsoPlainText>fax:Â <o:p></o:p></p><p class=MsoPlainText>954-418-9296<o:p></o:p></p><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></div></body></html>