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<DIV><FONT face=Arial size=2>Hello,</FONT></DIV>
<DIV><FONT face=Arial size=2>In light of recent questions to the list on the
ASHRAE ECB method, here is one that we are working on: </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The proposed multi-story office building will have
a cooling tower serving a condenser water loop. Each floor has a
VAV air handling unit with a water-cooled DX compressor, heat is rejected
to the CW loop. Economizer cooling is provided on the water side via
separate WSE coils. OA is provided to each floor's AHU, but 100% OA is not
provided. The waterside economizer coils can pre-cool the mixed air when
the CW temperature is low enough, and can run in series with the DX coils.
</FONT></DIV>
<DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Regarding the base budget building, the system map
in 90.1 seems to indicate that a central chiller plant is required for this type
of building (System type 2). However, in general I think we are supposed
to use consistent HVAC systems in the base budget building and the proposed
building. I want to know if we can use the floor-by-floor water cooled
units in the base budget building so as to be consistent and to not penalize the
energy performance of the floor-by-floor DX units compared to a chiller
plant.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Also, the language is confusing to us regarding air
vs. water side economizers. In 11.4.3, we are directed to include an
economizer that meets the requirements of 6.3.1, where the standard
seems to indicate that a system must have either air <EM>or</EM> water side
economizers. However, in 11.4.3e, the standard seems to say that system
type 2 must use airside economizers. The proposed design seems to meet the
requirements for waterside economizers, but I don't want to penalize the
proposed design for not having 100% OA capability. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Your thoughts on the above questions would be
appreciated.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Thanks!</FONT></DIV>
<DIV><FONT face=Arial size=2>Sincerely,</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Alec Stevens, PE, LEED AP<BR>DMI<BR>450 Lexington
St, Newton, MA 02466<BR>p: 617-527-1525 x105 f: 617-527-6606<BR>e: <A
href="mailto:astevens@dmiinc.com">astevens@dmiinc.com</A></FONT></DIV></DIV><PRE>
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