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<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff
size=2>Varkie,</FONT></SPAN></DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff
size=2>California's Title 24 energy code has established values of energy
credits for daylighting controls. These credits are used in both the
prescriptive approach and the performance method which is based upon an energy
simulation. For the LEED credits the performance method would be used as
you are trying to estimate the energy consumption as a fraction of the
consumption of a minimally compliant building. The current tool is
EnergyPro which is DOE-2.1E with a user interface that places
some limits on inputs and automatically creates a reference or minimally code
compliance comparison case. </FONT></SPAN></DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff size=2>The
lighting power of controlled lighting that is in the daylit zone (no more
than 15 feet from a window and currently no more than 1 ceiling height
horizontally from a skylight) is reduced by a Power Adjustment Factor
(PAF). The factor is a function of the visible transmittance and the
fraction of wall area for glazing. Though this doesn't capture peak
reduction effects, the simplicity of the method provides some confidence in the
results. Sensor placement has a huge impact on the
results.</FONT></SPAN></DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff size=2>The
Title 24 standards can be downloaded from: <A
href="http://www.energy.ca.gov/title24/">http://www.energy.ca.gov/title24/</A></FONT></SPAN></DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff size=2>I
don't know what rule set is involved for daylighting in DOE-2 when a geometry is
not described. I wouldn't expect that this would be an acceptable method
since you really do not know what you are modeling. The bottom line is
that your model approximates what your daylighting design does and that the
design would reasonably save energy - thus a lighting design that does not
provide the desired light levels in all the task locations would not likely
provide maintained savings. Modeling two sensors does not make any sense
if your control system has only one sensor and is designed to switch or
dim lights evenly across the entire control zone. "Virtual" sensors
are usually placed in a relatively dark spot in the controlled zone so that
electric lighting provides sufficient light in the entire zone on the lighting
control not just next to the window or directly under a skylight.
</FONT></SPAN></DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff
size=2>Modeling two sensors would make sense if the amount of dimming or
fraction of switched lights were segregated by how close they were to the window
or skylight. In that case you really have two separate control
zones.</FONT></SPAN></DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff size=2><!-- Converted from text/rtf format -->
<P><SPAN lang=en-us><FONT face=Garamond color=#800000>Jon McHugh, PE,
LC</FONT><BR>Heschong Mahone Group Inc.<BR>11626 Fair Oaks Blvd #302<BR>Fair
Oaks, CA 95628 (Sacramento)<BR>(916)962-7001<SPAN class=390164122-21012004> ext
38</SPAN><BR>(916)962-0101 FAX<BR>e-mail: mchugh@h-m-g.com<BR>URL:
www.h-m-g.com</SPAN> </P></FONT></SPAN></DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=390164122-21012004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV></DIV>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> Varkie Thomas
[mailto:Varkie.Thomas@som.com] <BR><B>Sent:</B> Wednesday, January 21, 2004 1:37
PM<BR><B>To:</B> BLDG-SIM@GARD.COM<BR><B>Subject:</B> [BLDG-SIM] Day-Lighting
and DOE2.1E<BR><BR></FONT></DIV>
<DIV class=Section1>
<P class=MsoNormal><FONT face="Times New Roman" color=navy size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: navy">Can day-lighting controls be considered for
LEED certification under “Energy & Atmosphere – Optimize Energy
Performance”? If so where should the light sensor be located in the space?
Is there any energy code that allows credit for day-lighting controls? The
DOE2 program allows two light sensors per space. Supposing the two sensors
are located 5 ft and 10 ft from the window. Is the average daylight at
these two points used in determining the reduction in artificial
lighting?</SPAN></FONT></P>
<P class=MsoNormal><FONT face="Times New Roman" color=navy size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: navy"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face="Times New Roman" color=navy size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: navy">The DOE2 program expects zones to have 6
surfaces defined with X,Y,Z coordinates and reflectance values for day-lighting
analysis. Ignoring this produces warning messages but the results show a
reduction in artificial lighting energy. For day-lighting analysis we only
enter into DOE2 the X,Y coordinates of the window origin relative to the wall
and also the wall and window dimensions. Can we assume that the energy
savings results from the DOE2 program are on the safe side (the actual energy
saved is more) when we use the program without all the surfaces and
coordinates?</SPAN></FONT></P>
<P class=MsoNormal><FONT face="Times New Roman" color=navy size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: navy"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face="Times New Roman" color=navy size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: navy">Are there any rules for day-lighting
analysis for establishing energy savings and for comparing the results from
different studies?</SPAN></FONT></P>
<P class=MsoNormal><FONT face="Times New Roman" color=navy size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: navy"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face="Times New Roman" color=navy size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: navy">Varkie Thomas</SPAN></FONT></P>
<P class=MsoNormal><FONT face="Times New Roman" color=navy size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: navy">Skidmore, Owings & Merrill
LLP</SPAN></FONT></P>
<P class=MsoNormal><FONT face="Times New Roman" color=navy size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: navy">Tel: (312) 360-4467
(direct)</SPAN></FONT></P></DIV><PRE>
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