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<DIV><FONT face=Arial size=2><SPAN class=255383916-18082006>I am modeling a
3-story office building, 40,000 sf (27,000 sf conditioned) in Seattle, WA,
consisting of parking garage, retail, and core spaces on the first floor;
and core plus open office spaces on the second and third floors. I am
trying to calculate the estimated energy cost savings for LEED NC 2.2, which
requires the use of a baseline energy model per ASHRAE 90.1-2004 Appendix G
guidelines.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=255383916-18082006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=255383916-18082006>The <STRONG>proposed
design</STRONG> uses a packaged VAV system to serve the core and office spaces,
consisting of: 1) a rooftop packaged AC unit with DX cooling, high efficiency
gas furnace, premium efficiency VSD fan motor, and economizer; and
2) series fan powered boxes with electric reheat at each zone.
Cooling supply air is delivered at 48F, and the DX coils have an EER of
11.7 (fan power removed). The building envelope includes 35% window to
wall ratio, average window assembly U-value of 0.385, and external wall assembly
R-value of R-11. The controls strategy for the VAV system cooling is
"reset for warmest zone."</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=255383916-18082006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=255383916-18082006>Per Appendix G, the
<STRONG>baseline model </STRONG>uses a constant volume, packaged rooftop unit
with DX cooling and electric heat pump. To reduce the number of hours
certain spaces were under-heated, I had to include some heat pump
supplemental electric heat and zone reheat. Cooling supply air is
delivered at 55F, and the DX coils have an EER of 11.6 (fan power
removed). The building envelope includes 35% window to wall ratio (same as
proposed design), average window assembly U-value of 0.595 (higher than proposed
design), external wall assembly R-value of R-8 (lower than proposed design), and
lighting power densities higher than in the proposed design.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=255383916-18082006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=255383916-18082006>Here is my
question: According to the results, the <STRONG>cooling</STRONG> energy
required for the <STRONG>proposed design</STRONG> model is about 30%
<STRONG>greater</STRONG> than the baseline model. This does not make sense
to me, since the proposed design model incorporates a VAV system with
economizer, slightly improved EER, and improved building envelope. (Fan
power is 72% lower and heating is 9% lower than the baseline model, which
seems reasonable.) Any thoughts on where there might be an error
in my modeling? I would appreciate any insights or
suggestions.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=255383916-18082006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN
class=255383916-18082006>Thanks,</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=255383916-18082006>Natasha
Houldson</SPAN></FONT><BR><BR><STRONG><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Natasha Houldson,
P.E.</SPAN></STRONG><BR><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN><FONT face=Arial
size=2>Mechanical Engineer</FONT><BR><BR><A href="http://www.glumac.com/"><IMG
src="http://www.glumac.com/glumacsig.gif" border=0></A>
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</DIV>
<DIV></DIV>
<DIV><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">320 SW
Washington, Suite 200</SPAN><BR><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">Portland,
OR 97204-2640</SPAN><BR><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">T.
503.227.5280<SPAN style="mso-spacerun: yes"> </SPAN>F.
503.274.7674</SPAN></DIV>
<DIV><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">D.
503.345.6285<BR><BR><STRONG><SPAN
style="FONT-SIZE: 10pt; COLOR: #333333; FONT-FAMILY: Arial">Thinking. Inside the
building.</SPAN></STRONG><BR><STRONG><SPAN
style="FONT-WEIGHT: normal; FONT-SIZE: 10pt; COLOR: #333333; FONT-FAMILY: Arial"><A
href="http://www.glumac.com/">www.glumac.com</A></SPAN></STRONG></SPAN> </DIV>
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