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<DIV dir=ltr align=left><SPAN class=328280315-12012009><FONT face=Arial
color=#0000ff size=2>p.s.,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=328280315-12012009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=328280315-12012009><FONT face=Arial
color=#0000ff size=2>You can get a custom air handler and coils with almost any
capacity you can dream of. In the case of coils, multiple coils can be
used in a single air handler. It's not so common to use very large air handlers
because of space restraints and distribution issues, but there are plenty of
them in use. Once again, the model doesn't care about physical size, only
physics :)</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<?xml:namespace prefix = o ns =
"urn:schemas-microsoft-com:office:office" /><o:p></o:p></P>
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<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>Ulrik
Welle-Strand Horn<BR><B>Sent:</B> Saturday, January 10, 2009 5:15
AM<BR><B>To:</B> bldg-sim@lists.onebuilding.org<BR><B>Subject:</B> [Bldg-sim]
Appendix G - Exhaust Air Energy Recovery/Number ofBaseline Fan
Systems<BR></FONT><BR></DIV>
<DIV></DIV>Dear All,<BR><BR>I am curious how many systems or fan systems most of
you usually create when you model baseline systems? <BR><BR>I am particularly
interested because under point G3.1.2.10 - Exhaust Air Energy Recovery, one only
has to apply an energy recovery device if a single fan system is larger than
5000 cfm. I have not seen anywhere (please direct me if there is indeed
prescriptions for this in an ASHRAE publication) guidelines for how many fan
systems one has to model in a baseline building? It seems that if I have a
building with let's say 15000 cfm supply air, I am free to model this building's
baseline system with either 2 or 4 fan systems? Then, if I model this building
with 4 fan systems (each system sized equally at 3750 cfm), I would not have to
use energy recovery in the baseline building, while if I choose to model the
baseline with 2 fan systems (each sized equally at 7500 cfm), then I must use
energy recovery.<BR><BR>I would also appreciate input on a typical size of a fan
system. If I have a building that has a supply design air flow requirement of
100,000 cfm, how many fan systems would typically be modeled? I am not too
familiar with HVAC design, and I tried looking for clues at manufacturers'
websites but only Carrier indicated an upper threshold of about 150 tons for
their coils. Does anyone have an experience with a typical airflow for a very
hot climate over a 150 ton coil? I am looking at System 8 for my baseline
building, and I imagine that for a large building (35 stories), several coils
will be installed. I am using Trace to do the energy model, and for some reason,
the more systems I model the higher the energy usage, keeping everything else
constant. Therefore I am interested in modeling several fan systems, if that is
common design practice.<BR><BR>Lastly, I would like to confirm that the design
of the baseline system beyond what is stipulated in Appendix G should comply
with common practice? In particular, numbers and sizes of systems does not seem
to be much discussed in Appendix G. Please let me know if you share my approach
in applying common design practices to size and locate equipment beyond Appendix
G prescriptions.<BR><BR>I appreciate any feedback you might have on these
issues.<BR><BR>Faithfully yours,<BR><BR><BR><B>Ulrik Welle-Strand Horn
</B><BR>Sustainability Engineer<BR>
<DIV><BR><B>Silpa Inc.</B><BR><FONT size=1><B>s</B> i m p l e .
<B>s</B> c i e n t i f i c . <B>s</B> u s t a i n a b l
e<BR></FONT></DIV><FONT size=1>
<DIV>AMERICAS | MIDDLE EAST | ASIA<BR><A href="http://www.silpainc.com/"
target=_blank>www.silpainc.com</A><BR></DIV><FONT size=2><BR></FONT></FONT><FONT
size=2>India: +91.90080.96083</FONT><BR><BR></BODY></HTML>