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<div class=Section1>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>To further complicate things, the target footcandle level of the
daylight harvesting system will vary depending on whether the space uses tasks
lights or not. With task lights, the overhead lighting system can be configured
to provide an even lower target footcandle level. I don’t know the correct
answer, but I’ve always used 30 footcandles for the target lighting level in
typical office projects (most of them have task lights). If it’s a GSA
project, where they are very specific about the required workspace lighting
levels, you might need to use predefined owner requirements for the target
levels…<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div>
<p class=MsoNormal><b><span style='font-family:"Arial","sans-serif";color:teal'>GHT
Limited<br>
</span></b><b><span style='font-size:11.0pt;font-family:"Arial","sans-serif"'><ns0:PersonName><span
style='color:black'>James Hansen</span></ns0:PersonName></span></b><b><span
style='color:black'>, PE, LEED AP<o:p></o:p></span></b></p>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Senior Associate</span></b><b><span style='color:black'><o:p></o:p></span></b></p>
<p class=MsoNormal><span style='font-size:7.5pt;font-family:"Arial","sans-serif"'><ns0:Street><ns0:address><span
style='color:black'>1010 N. Glebe Rd, Suite 200</span></ns0:address></ns0:Street></span><span
style='color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:7.5pt;font-family:"Arial","sans-serif"'><ns0:place><ns0:City><span
style='color:black'>Arlington</span></ns0:City><span style='color:black'>, </span><ns0:State><span
style='color:black'>VA</span></ns0:State><span style='color:black'> </span><ns0:PostalCode><span
style='color:black'>22201-4749</span></ns0:PostalCode></ns0:place></span><span
style='color:black'><o:p></o:p></span></p>
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color:black'>703-338-5754 (Cell)</span><span style='color:black'><o:p></o:p></span></p>
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color:black'>703-243-1200 (Office)</span><span style='color:black'><o:p></o:p></span></p>
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color:black'>703-276-1376 (Fax)</span><span style='color:black'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Arial","sans-serif";
color:teal'><a href="http://www.ghtltd.com/"><span style='font-size:10.0pt'>www.ghtltd.com</span></a><o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
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<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <b>On Behalf Of </b>Jonathan
Catterall<br>
<b>Sent:</b> Tuesday, June 30, 2009 9:03 AM<br>
<b>To:</b> bldg-sim@lists.onebuilding.org<br>
<b>Subject:</b> [Bldg-sim] 90.1 Appendix G: Daylight Utilization<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Building-Sim
users,</span><o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Perhaps
somebody could shed some light on this issue for me.</span><o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>In
90.1 Appendix G, Table G3.1, Section 6.f. states that credit can be taken in
the proposed building for automatic controls due to daylight utilization.
However:</span><o:p></o:p></p>
<ul type=disc>
<li class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;
mso-list:l0 level1 lfo1'><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>In
order to know how much of an effect daylight should have on the power
used, a target luminance/lux level is required. If this target is met
by daylight alone, the lighting consumption would drop to 0 (except for
emergency lighting). Where daylight falls between 0 and the target lux level,
lighting power can be scaled linearly.</span><o:p></o:p></li>
</ul>
<ul type=disc>
<li class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;
mso-list:l2 level1 lfo2'><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>The
documentation gives no target lux levels and they cannot be derived from
the baseline lighting power densities (from 90.1 Sections 9.5.1/9.6.1)
without knowing the efficiencies associated with these values.</span><o:p></o:p></li>
</ul>
<ul type=disc>
<li class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;
mso-list:l1 level1 lfo3'><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>The
only related luminance levels available are from the IESNA Lighting
Handbook but these levels do not seem to sensibly correlate with the power
densities of 90.1 Sections 9.5.1/9.6.1. Take, for example, a
drafting office. The IESNA Lighting Handbook Section 10, Quality of
the Visual Environment, suggests a lighting level of around 100fc (1076
lux). Achieving this 100 fc with an LPD of 1.1W/ft²
(11.83W/m²), i.e. that quoted for an Open Plan Office, requires a lamp
with an efficiency of approximately 91 lumens/watt. Using the same
Lighting Power Density, and illuminance of 30fc for simple office tasks,
we require lights that produce 27 lumens/watt. This gives us two
spaces that are classified identically, but are subject to massively
different limitations when it comes to selecting lamps.</span><o:p></o:p></li>
</ul>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Could
somebody please provide some clarification on whether it is wise to assume
these lux levels while performing a Building Performance Method simulation,
bearing in mind that it could affect results in an unfavourable way if lux
level is overestimated (as LPD will be constant in the baseline buildings).</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Regards,</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Jonathan
Catterall</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
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<td width=229 nowrap style='width:172.1pt;padding:0in 0in 0in 0in'>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:10.0pt;color:navy'><a href="http://www.edsl.net/"><span
style='font-size:12.0pt;color:navy;text-decoration:none'><img border=0
width=214 height=50 id="_x0000_i1025" src="cid:image001.gif@01C9F965.2883F700"></span></a></span><o:p></o:p></p>
</td>
<td width=153 nowrap style='width:115.1pt;padding:0in 0in 0in 0in'>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span
style='font-family:"Arial","sans-serif";color:#333333'>Jonathan <span
class=spelle>Catterall</span><br>
</span></b><span class=spelle><span style='font-size:8.0pt;font-family:"Arial","sans-serif";
color:#999999'>BSc</span></span><span style='font-size:8.0pt;font-family:
"Arial","sans-serif";color:#999999'> (<span class=spelle>Hons</span>) <span
class=spelle>Dunelm</span>, <span class=spelle>MSc</span><br>
Software Developer</span><o:p></o:p></p>
</td>
<td width=160 nowrap style='width:119.8pt;padding:0in 0in 0in 0in'>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#CC0000'><a
href="mailto:jonathan@edsl.net"><span style='color:#CC0000;text-decoration:
none'>jonathan@edsl.net</span></a></span><span style='font-size:10.0pt;
font-family:"Arial","sans-serif";color:navy'><br>
</span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#333333'>Tel: +44 (0)1908 261461</span><span style='font-size:10.0pt;
font-family:"Arial","sans-serif";color:navy'><br>
</span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#CC0000'><a href="http://www.edsl.net/" title="http://www.edsl.net/"><span
style='color:#CC0000;text-decoration:none'>http://www.edsl.net</span></a></span><o:p></o:p></p>
</td>
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<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'> <o:p></o:p></p>
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