<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML xmlns="http://www.w3.org/TR/REC-html40" 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"><HEAD>
<META http-equiv=Content-Type content="text/html; charset=us-ascii">
<META content="MSHTML 6.00.6000.16788" name=GENERATOR>
<STYLE>@font-face {
font-family: Cambria Math;
}
@font-face {
font-family: Calibri;
}
@page Section1 {size: 8.5in 11.0in; margin: 1.0in 1.0in 1.0in 1.0in; }
P.MsoNormal {
FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Calibri","sans-serif"
}
LI.MsoNormal {
FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Calibri","sans-serif"
}
DIV.MsoNormal {
FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: "Calibri","sans-serif"
}
A:link {
COLOR: blue; TEXT-DECORATION: underline; mso-style-priority: 99
}
SPAN.MsoHyperlink {
COLOR: blue; TEXT-DECORATION: underline; mso-style-priority: 99
}
A:visited {
COLOR: purple; TEXT-DECORATION: underline; mso-style-priority: 99
}
SPAN.MsoHyperlinkFollowed {
COLOR: purple; TEXT-DECORATION: underline; mso-style-priority: 99
}
P.MsoListParagraph {
FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt 0.5in; FONT-FAMILY: "Calibri","sans-serif"; mso-style-priority: 34
}
LI.MsoListParagraph {
FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt 0.5in; FONT-FAMILY: "Calibri","sans-serif"; mso-style-priority: 34
}
DIV.MsoListParagraph {
FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt 0.5in; FONT-FAMILY: "Calibri","sans-serif"; mso-style-priority: 34
}
SPAN.EmailStyle17 {
COLOR: windowtext; FONT-FAMILY: "Calibri","sans-serif"; mso-style-type: personal-compose
}
.MsoChpDefault {
mso-style-type: export-only
}
DIV.Section1 {
page: Section1
}
OL {
MARGIN-BOTTOM: 0in
}
UL {
MARGIN-BOTTOM: 0in
}
</STYLE>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</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 vLink=purple link=blue>
<DIV dir=ltr align=left><SPAN class=718183315-08012009><FONT face=Arial
color=#0000ff size=2>Dear Paul,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=718183315-08012009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=718183315-08012009><FONT face=Arial
color=#0000ff size=2>In theory, the return plenum is warmer than the occupied
space, so the wall and, especially, roof loads do not affect the space in the
same way. This will give a warmer coil entering condition and resulting
smaller coil, fan, duct, motor, wiring, electrical service,
etc.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=718183315-08012009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=718183315-08012009><FONT face=Arial
color=#0000ff size=2>The ACTUAL difference will be small and may not be worth
the additional analysis and load calculations. You could argue that a VAV
system will realize the benefits, since it will "see" the space load only and
reduce volume to suit.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=718183315-08012009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=718183315-08012009><FONT face=Arial
color=#0000ff size=2>Another consideration is whether the life cycle energy
benefits outweigh the differential cost to install and maintain the suspended
ceiling.... I suspect they do, but am uncertain re:
ROI.</FONT></SPAN></DIV>
<DIV> </DIV>
<DIV class=Section1>
<P class=MsoNormal style="TEXT-ALIGN: center" align=center><B
style="mso-bidi-font-weight: normal"><FONT size=4>The Building Performance
Team<BR></FONT></B><B style="mso-bidi-font-weight: normal">James V. Dirkes II,
P.E., LEED AP<BR></B>1631 Acacia Drive NW<BR>Grand Rapids, MI 49504<BR>616
450 8653<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P></DIV>
<DIV> </DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <B>On Behalf Of </B>P.
Hay<BR><B>Sent:</B> Thursday, January 08, 2009 10:19 AM<BR><B>To:</B>
BLDG-SIM<BR><B>Subject:</B> [Bldg-sim] Suspended ceilings vs. open
plenums<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=Section1>
<P class=MsoNormal>Hi all,<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>I recently came across a Life Cycle Analysis of Suspended
Ceilings vs. Open Plenums, initiated by CISCA [Ceiling and Interior System
Construction Association ( <A href="http://www.cisca.org">www.cisca.org</A> )]
which concluded that suspended ceilings are more energy efficient because they
have:<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoListParagraph
style="TEXT-INDENT: -0.25in; mso-list: l0 level1 lfo1"><![if !supportLists]><SPAN
style="mso-list: Ignore">a)<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN><![endif]>higher reflectances,<o:p></o:p></P>
<P class=MsoListParagraph
style="TEXT-INDENT: -0.25in; mso-list: l0 level1 lfo1"><![if !supportLists]><SPAN
style="mso-list: Ignore">b)<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN><![endif]>better heat-removal from luminaires, and<o:p></o:p></P>
<P class=MsoListParagraph
style="TEXT-INDENT: -0.25in; mso-list: l0 level1 lfo1"><![if !supportLists]><SPAN
style="mso-list: Ignore">c)<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN><![endif]>use lower static pressure and fan power.<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>I can understand (a) and (c) but (b) leaves me suspicious
that the return-air plenum was not considered in this study. As I
understand it, return-air plenums can be defined as separate zones from the
usable spaces (in this case: an office or a food store) but the suspended
ceilings are adiabatic. So , other than the savings for lighting and fan,
I really don’t understand how there could be significant savings for the HVAC
system if the overall height of the rooms (plenum & usable space) is
identical, and cooling load of plenums are considered. <o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Is there something I’m missing?<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Paul Hay<o:p></o:p></P>
<P class=MsoNormal>Managing Partner<o:p></o:p></P>
<P class=MsoNormal>PAUL HAY Consultants<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal><I>Capital Project Planning and Management<o:p></o:p></I></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>15a Cassia Park Road<o:p></o:p></P>
<P class=MsoNormal>Kingston 10<o:p></o:p></P>
<P class=MsoNormal>Jamaica, W.I.<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>tel: 1 (876) 756-0631<o:p></o:p></P>
<P class=MsoNormal>cel: 1 (876) 324-4274<o:p></o:p></P>
<P class=MsoNormal>fax: 1 (876) 756-0631<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>web: www.phcjamaica.com<o:p></o:p></P>
<P class=MsoNormal>e-mail: paul.hay@phcjamaica.com<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P></DIV></BODY></HTML>