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<P>Vikram:</P>
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<P>I agree with James. Chiller energy would be measured in electric or gas units (energy input)..</P>
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<P>Ton-hours is a load (useful energy) function.</P>
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<B><SPAN style="FONT-WEIGHT: bold">From:</SPAN></B> "James V Dirkes II, PE" <jvd2pe@tds.net><BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B> "Sami, Vikram" <Vikram.Sami@perkinswill.com>; "bldg-sim@lists.onebuilding.org" <Bldg-sim@lists.onebuilding.org><BR><B><SPAN style="FONT-WEIGHT: bold">Sent:</SPAN></B> Fri, September 10, 2010 2:30:19 PM<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B> Re: [Bldg-sim] A Question about chilled water usage<BR></FONT><BR>
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<P class=MsoNormal><SPAN style="COLOR: #1f497d"> </SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: #1f497d">Dear Vikram,</SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: #1f497d">I think that the definition of ton-hours is inherently an “cooling energy delivered” or “useful energy”, metric.</SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: #1f497d"> </SPAN></P>
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<P style="TEXT-ALIGN: center" class=MsoNormal align=center><B><SPAN style="FONT-FAMILY: 'serif'; COLOR: #1f497d; FONT-SIZE: 13.5pt">The Building Performance Team<BR></SPAN></B><B><SPAN style="FONT-FAMILY: 'serif'; COLOR: #1f497d; FONT-SIZE: 12pt">James V. Dirkes II, P.E., LEED AP<BR></SPAN></B><SPAN style="FONT-FAMILY: 'serif'; COLOR: #1f497d; FONT-SIZE: 12pt">1631 Acacia Drive NW<BR>Grand Rapids, MI 49504<BR>616 450 8653</SPAN></P></DIV>
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<P style="MARGIN-LEFT: 0.5in" class=MsoNormal><B><SPAN style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">From:</SPAN></B><SPAN style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt"> bldg-sim-bounces@lists.onebuilding.org [mailto:bldg-sim-bounces@lists.onebuilding.org] <B>On Behalf Of </B>Sami, Vikram<BR><B>Sent:</B> Friday, September 10, 2010 4:23 PM<BR><B>To:</B> bldg-sim@lists.onebuilding.org<BR><B>Subject:</B> [Bldg-sim] A Question about chilled water usage</SPAN></P></DIV></DIV>
<P style="MARGIN-LEFT: 0.5in" class=MsoNormal> </P>
<P style="MARGIN-LEFT: 0.5in" class=MsoNormal>I’m looking at utility data for a building on a college campus that has a central utility plant. They list cooling energy in ton-hrs and It seems really high for all buildings across the board. </P>
<P style="MARGIN-LEFT: 0.5in" class=MsoNormal> </P>
<P style="MARGIN-LEFT: 0.5in" class=MsoNormal>However – if you assume that ton-hrs is the metered chilled water usage and not the chiller energy, its not that bad. For example if the chilled water usage is 1 ton-hrs, that’s 12,000 BTU’s of cooling energy delivered. However, if whats being measured is chilled water usage (and not chiller energy), then 1 ton-hr is not the energy consumed by the chiller – that should be 12,000BTU/COP of the chiller. So if the chiller COP is 4 – then that’s only 3,000 BTU’s of energy consumed to deliver that ton-hr.</P>
<P style="MARGIN-LEFT: 0.5in" class=MsoNormal> </P>
<P style="MARGIN-LEFT: 0.5in" class=MsoNormal>So – to get to the point – does anyone know if campuses monitor their chilled water usage (in ton-hrs) as chiller energy or cooling delivered?</P>
<P style="MARGIN-LEFT: 0.5in" class=MsoNormal> </P>
<P style="MARGIN-LEFT: 0.5in" class=MsoNormal>(I hope this makes snese)</P>
<P style="MARGIN-LEFT: 0.5in" class=MsoNormal> </P>
<P style="MARGIN-LEFT: 0.5in" class=MsoNormal><B><SPAN style="FONT-FAMILY: 'sans-serif'; COLOR: gray; FONT-SIZE: 9pt">Vikram Sami</SPAN></B><SPAN style="FONT-FAMILY: 'sans-serif'; COLOR: gray; FONT-SIZE: 9pt">, LEED AP</SPAN></P>
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