<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<!--[if !mso]><style>v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style><![endif]--><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:"Franklin Gothic Medium";
panose-1:2 11 6 3 2 1 2 2 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
font-size:11.0pt;
font-family:"Calibri",sans-serif;
mso-ligatures:standardcontextual;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;
mso-ligatures:standardcontextual;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1029" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="#0563C1" vlink="#954F72" style="word-wrap:break-word">
<div class="WordSection1">
<p class="MsoNormal"><a name="_Hlk124516833"></a><a name="_Hlk124516947"></a><a name="_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833">Hey All,<span style="mso-ligatures:none"><o:p></o:p></span></span></span></a></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><o:p> </o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833">Just a tip/FYI for modeling DCV. Comments, anecdotes and non-sequiturs encouraged!<o:p></o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833">I have modeled, or at least thought I modeled, demand controlled ventilation many times in eQUEST by setting the
SYSTEM:MIN-OA-METHOD to DCV-RETURN-SENSOR or DCV-ZONE-SENSORS, making sure I enter the correct number of people in the spaces, using an occupancy schedule that varies, and specifying the people-based ventilation using ZONE:OA-FLOW/PER. However, I recently
discovered what I believe are additional steps.<o:p></o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833">I am modeling a variable 100% OA MAU serving a laundry by entering the total OA requirement using people-based ventilation.
There are 9 dryers, which I modeled as 9 people, and zone OA-FLOW/PER of 220 giving a total OA requirement of 1980 cfm for the MAU. The occupancy schedule is a good proxy for dryer use, so it should work out in principle.<o:p></o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833">I modeled the system as PSZ packaged single zone and set the SYSTEM:FAN-CONTROL to FAN-EIR-FPLR and used the ASHRAE
App. G fan curve. However, the SYSTEM:MIN-FLOW-RATIO defaults to 1.0 even after setting the fan to variable control. If you adjust the SYSTEM:MIN-FLOW-RATIO to something else (let’s say 0.2) and make no other changes, the system operates at that minimum flow
at all hours (and should run at higher flow to meet the thermostat setpoint if I had a higher T-stat setpoint). However, it does NOT simulate DCV.<o:p></o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833">In order to get a PSZ system to simulate DCV, you need to do all of the above PLUS set the ZONE:MIN-FLOW-CTRL to
DCV-RESET-UP to allow the hourly flowrate to go above the MIN-FLOW-RATIO based on the people-based ventilation rate and schedule. You will not be able to select it from the drop-down menu, so you have to enter #SI("DCV-RESET-UP","ZONE","MIN-FLOW-CTRL") as
a user expression for that zone (or zones). Now it WILL simulate DCV, as verified in the SS-L report for system fan electric energy use.<o:p></o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833">Before I figured that out, I tried modeling the system as PVAV. For the PVAV system, any value for SYSTEM:FAN-CONTROL
other than CONSTANT-VOLUME gives a SYSTEM:MIN-FLOW-RATIO of no_default (no value – an empty box). CONSTANT-VOLUME gives a 1.0 MIN-FLOW-RATIO which won’t allow DCV. Regardless of which SYSTEM:MIN-OA-METHOD setting you use, including DCV-RETURN- or DCV-ZONE-SENSORS,
the ZONE:MIN-FLOW-CONTROL defaults to FIXED/SCHEDULED, which will NOT simulate DCV. To simulate DCV, you have to set the ZONE:MIN-FLOW-CONTROL to DCV-RESET-DOWN. Alternatively, you can enter a ZONE:MIN-FLOW-RATIO less than 1 (say, 0.2) and set the ZONE:MIN-FLOW-CONTROL
to DCV-RESET-UP.<o:p></o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833">I have not tried modeling DCV with a VAV system lately (not PVAV), but it probably requires similar inputs to the
PVAV system at the SYSTEM and ZONE(s).<o:p></o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833">Any of the options above can be modified by setting the SYSTEM:MIN-AIR-SCHEDULE, which you should do regardless in
most situations to model zero OA when the system is in night-cycling mode, except for a MAU which should always be 100% OA.<o:p></o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><o:p> </o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833">TL;DR version: Read the above next time you want to be confident you’re actually modeling DCV.<o:p></o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><o:p> </o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833">~Bill<o:p></o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><o:p> </o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><b><span style="font-size:10.0pt;font-family:"Franklin Gothic Medium",sans-serif;color:black;mso-ligatures:none">William
Bishop, PE, BEMP, BEAP, CEM, LEED AP </span></b></span></span></span><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><b><span style="font-size:10.0pt;font-family:"Franklin Gothic Medium",sans-serif;color:green;mso-ligatures:none">|</span></b></span></span></span><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><b><span style="font-size:10.0pt;font-family:"Franklin Gothic Medium",sans-serif;color:#0F243E;mso-ligatures:none">
</span></b></span></span></span><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><b><span style="font-size:10.0pt;font-family:"Franklin Gothic Medium",sans-serif;mso-ligatures:none">Pathfinder
Engineers & Architects LLP<span style="color:black"><o:p></o:p></span></span></b></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:black;mso-ligatures:none">Senior Energy Engineer<o:p></o:p></span></b></span></span></span></p>
<p class="MsoNormal"><!--[if gte vml 1]><v:shapetype id="_x0000_t75" coordsize="21600,21600" o:spt="75" o:preferrelative="t" path="m@4@5l@4@11@9@11@9@5xe" filled="f" stroked="f">
<v:stroke joinstyle="miter" />
<v:formulas>
<v:f eqn="if lineDrawn pixelLineWidth 0" />
<v:f eqn="sum @0 1 0" />
<v:f eqn="sum 0 0 @1" />
<v:f eqn="prod @2 1 2" />
<v:f eqn="prod @3 21600 pixelWidth" />
<v:f eqn="prod @3 21600 pixelHeight" />
<v:f eqn="sum @0 0 1" />
<v:f eqn="prod @6 1 2" />
<v:f eqn="prod @7 21600 pixelWidth" />
<v:f eqn="sum @8 21600 0" />
<v:f eqn="prod @7 21600 pixelHeight" />
<v:f eqn="sum @10 21600 0" />
</v:formulas>
<v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect" />
<o:lock v:ext="edit" aspectratio="t" />
</v:shapetype><v:shape id="Picture_x0020_7" o:spid="_x0000_s1028" type="#_x0000_t75" alt="Logo, company nameDescription automatically generated" style='position:absolute;margin-left:1.5pt;margin-top:4.7pt;width:178.75pt;height:66.75pt;z-index:-251657216;visibility:visible;mso-wrap-style:square;mso-width-percent:0;mso-height-percent:0;mso-wrap-distance-left:9pt;mso-wrap-distance-top:0;mso-wrap-distance-right:9pt;mso-wrap-distance-bottom:0;mso-position-horizontal:absolute;mso-position-horizontal-relative:text;mso-position-vertical:absolute;mso-position-vertical-relative:text;mso-width-percent:0;mso-height-percent:0;mso-width-relative:page;mso-height-relative:page' o:allowincell="f">
<v:imagedata src="cid:image001.jpg@01D95C01.6E550A90" o:title="Logo, company nameDescription automatically generated" />
<w:wrap type="square"/>
</v:shape><![endif]--><![if !vml]><img width="238" height="89" style="width:2.4791in;height:.927in" src="cid:image007.jpg@01D95C04.B8F9E630" align="left" hspace="12" alt="Logo, company nameDescription automatically generated" v:shapes="Picture_x0020_7"><![endif]><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"></span></span></span><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><b><i><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#002060;mso-ligatures:none">
T: (585) 698-1956</span></i></b></span></span></span><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><b><i><span style="color:#002060;mso-ligatures:none">
</span></i></b></span></span></span><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"></span></span></span><a href="http://www.pathfinder-ea.com"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#0563C1;mso-ligatures:none">www.pathfinder-ea.com</span></span></span></span><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"></span></span></span></a><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><b><span style="font-size:3.0pt;font-family:"Arial",sans-serif;color:black;mso-ligatures:none"><o:p></o:p></span></b></span></span></span></p>
<p class="MsoNormal"><!--[if gte vml 1]><v:shape id="Picture_x0020_6" o:spid="_x0000_s1027" type="#_x0000_t75" alt="IconDescription automatically generated" style='position:absolute;margin-left:316.8pt;margin-top:1.85pt;width:44.65pt;height:30.25pt;z-index:-251656192;visibility:visible;mso-wrap-style:square;mso-width-percent:0;mso-height-percent:0;mso-wrap-distance-left:9pt;mso-wrap-distance-top:0;mso-wrap-distance-right:9pt;mso-wrap-distance-bottom:0;mso-position-horizontal:absolute;mso-position-horizontal-relative:text;mso-position-vertical:absolute;mso-position-vertical-relative:text;mso-width-percent:0;mso-height-percent:0;mso-width-relative:page;mso-height-relative:page'>
<v:imagedata src="cid:image003.png@01D95C01.6E550A90" o:title="IconDescription automatically generated" />
</v:shape><![endif]--><![if !vml]><span style="mso-ignore:vglayout;position:absolute;z-index:-1895823360;margin-left:422px;margin-top:3px;width:60px;height:40px"><img width="60" height="40" style="width:.625in;height:.4166in" src="cid:image008.jpg@01D95C04.B8F9E630" alt="IconDescription automatically generated" v:shapes="Picture_x0020_6"></span><![endif]><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"></span></span></span><!--[if gte vml 1]><v:shape id="Picture_x0020_9" o:spid="_x0000_s1026" type="#_x0000_t75" style='position:absolute;margin-left:367.2pt;margin-top:1.85pt;width:28.1pt;height:30.25pt;z-index:-251655168;visibility:visible;mso-wrap-style:square;mso-width-percent:0;mso-height-percent:0;mso-wrap-distance-left:9pt;mso-wrap-distance-top:0;mso-wrap-distance-right:9pt;mso-wrap-distance-bottom:0;mso-position-horizontal:absolute;mso-position-horizontal-relative:text;mso-position-vertical:absolute;mso-position-vertical-relative:text;mso-width-percent:0;mso-height-percent:0;mso-width-relative:margin;mso-height-relative:margin'>
<v:imagedata src="cid:image005.png@01D95C01.6E550A90" o:title="" />
</v:shape><![endif]--><![if !vml]><span style="mso-ignore:vglayout;position:absolute;z-index:-1895822336;margin-left:490px;margin-top:3px;width:37px;height:40px"><img width="37" height="40" style="width:.3854in;height:.4166in" src="cid:image009.jpg@01D95C04.B8F9E630" v:shapes="Picture_x0020_9"></span><![endif]><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"></span></span></span><a href="mailto:bbishop@pathfinder-ea.com"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:black;mso-ligatures:none">bbishop@pathfinder-ea.com</span></span></span></span><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"></span></span></span></a><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#1F497D;mso-ligatures:none">
<o:p></o:p></span></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#1F497D;mso-ligatures:none">134 South Fitzhugh
Street<o:p></o:p></span></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124429695"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#1F497D;mso-ligatures:none">Rochester, NY 14608<o:p></o:p></span></span></span></span></p>
<span style="mso-bookmark:_Hlk124429695"></span>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><span style="font-size:6.0pt;font-family:"Arial",sans-serif;color:#0F243E;mso-ligatures:none"><o:p> </o:p></span></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_Hlk124516947"><span style="mso-bookmark:_Hlk124516833"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#0F243E;mso-ligatures:none">Buffalo Office: 100 Corporate Parkway, Suite 116, Amherst, NY
14226<o:p></o:p></span></span></span></p>
<span style="mso-bookmark:_Hlk124516833"></span><span style="mso-bookmark:_Hlk124516947"></span>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</body>
</html>