<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:10pt"><div>Michael:<br><br>"if the air in duct is the same air as the air being supplied to the space, there is no net effect"? What do you mean by net effect?<br><br>The duct heat loss/gain depends on the difference of the temperature of the air in the duct and the temperature of the air surrounding the outside of the duct. It is highly unlikely that these temperature will be the same.<br><br>Paul Diglio<br></div><div style="font-family: times new roman,new york,times,serif; font-size: 10pt;"><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> "McArdle, Mike" <Mike.McAardle@state.vt.us><br><b><span style="font-weight: bold;">To:</span></b> xiaoyang shi
<xs2144@gmail.com>; "equest-users@lists.onebuilding.org" <equest-users@lists.onebuilding.org><br><b><span style="font-weight: bold;">Sent:</span></b> Tue, March 29, 2011 5:39:40 PM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [Equest-users] question about inefficiency of duct<br></font><br>
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--></style><div class="WordSection1"><p class="MsoNormal"><span style="font-size: 10pt; font-family: "sans-serif";">Dear xiaoyang shi</span><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">It Depends on the temperature differentials between air in duct and space and insulation thickness </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">But more importantly , if the air in duct is the same air as the air being supplied to the space there is
no net effect </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Thank you, Sincerely,</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Michael J. McArdle , P.E.</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Buildings Engineer II, Project Manager </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family:
"sans-serif"; color: rgb(31, 73, 125);">State of Vermont, </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Buildings and General Services (BGS)</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">2 Governor Aiken Avenue</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Montpelier, Vt. 05633</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Office: 802-828-5650; cell: 802-272-4828</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">
</span></p><div style="border-width: 1pt medium medium; border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; padding: 3pt 0in 0in;"><p class="MsoNormal"><b><span style="font-size: 10pt; font-family: "sans-serif";">From:</span></b><span style="font-size: 10pt; font-family: "sans-serif";"> equest-users-bounces@lists.onebuilding.org [mailto:equest-users-bounces@lists.onebuilding.org] <b>On Behalf Of </b>xiaoyang shi<br><b>Sent:</b> Tuesday, March 29, 2011 5:37 PM<br><b>To:</b> equest-users@lists.onebuilding.org<br><b>Subject:</b> [Equest-users] question about inefficiency of duct</span></p></div><p class="MsoNormal"> </p><p class="MsoNormal">Hi folks,<br><br>In the winter time, some heat loss in HVAC is from duct.<br><br>What is the percentage of heat loss through the duct to the total building heat load, due to the inefficiencies of duct delivery system?<br><br>Thank you
guys.<br><br><br></p></div></div></div>
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