<div>Hi James, </div>
<div> </div>
<div> </div>
<div>The CIR is dated on 3/23/2007. It clarifies use of exception to G.3.1.1. to document baseline and achieve greater energy savings from single-zone systems in <strong><u>high</u></strong> process load areas. </div>
<div> </div>
<div>As per G3.1.1. in Appendix G (90.1-2004), my understanding is to use separate single-zone system for any space has very high occupancy or process loads or schedules that differ significantly from the rest of the building. You can understand it in the opposite way that the rooms have significantly less occupancy or process loads. But I guess the CIR points to the high process load areas in order to achieve greater energy savings from single-zone systems. </div>
<div> </div>
<div>Regards, </div>
<div>Cheney <br><br></div>
<div class="gmail_quote">On Mon, Nov 1, 2010 at 12:46 PM, James Hansen <span dir="ltr"><<a href="mailto:JHANSEN@ghtltd.com">JHANSEN@ghtltd.com</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">
<div lang="EN-US" vlink="purple" link="blue">
<div>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt">Thanks Cheney, but I’m not sure I follow your email. I’ve already determined that, for example, a core bathroom could easily have a peak load that is 10 Btu/hr-ft2 less than the peak average of the rest of my spaces. Same goes for stairs, storage rooms, etc. So doesn’t 90.1 REQUIRE that I model these separately?</span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt"> </span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt">What CIR are you referencing?</span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt"> </span></p>
<div style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; PADDING-BOTTOM: 0in; PADDING-LEFT: 0in; PADDING-RIGHT: 0in; BORDER-TOP: #b5c4df 1pt solid; BORDER-RIGHT: medium none; PADDING-TOP: 3pt">
<p class="MsoNormal"><b><span style="FONT-SIZE: 10pt">From:</span></b><span style="FONT-SIZE: 10pt"> Cheney [mailto:<a href="mailto:chenyu73@gmail.com" target="_blank">chenyu73@gmail.com</a>] <br><b>Sent:</b> Monday, November 01, 2010 12:36 PM<br>
<b>To:</b> James Hansen<br><b>Cc:</b> <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a><br><b>Subject:</b> Re: [Bldg-sim] Exceptions to G3.1.1, and how you model them?</span></p>
</div>
<div>
<div></div>
<div class="h5">
<p class="MsoNormal"> </p>
<div>
<p class="MsoNormal">Hi James, </p></div>
<div>
<p class="MsoNormal"> </p></div>
<div>
<p class="MsoNormal">LEED CIR allows projects to demonstrate substantial energy savings for well-designed HVAC system serving high process load spaces based on the exception to G3.1.1. So the premise is "high occupancy or process load" spaces, such as server rooms, natatoriums, before it comes to the benchmark of 10 btu/h-ft2. Therefore, I guess your storage rooms, stairs, mechanical rooms should not be modeled separately. </p>
</div>
<div>
<p class="MsoNormal"> </p></div>
<div>
<p class="MsoNormal">Regards, </p></div>
<div>
<p class="MsoNormal"> </p></div>
<div>
<p class="MsoNormal">Cheney </p></div>
<div>
<p class="MsoNormal"> </p></div>
<div>
<p style="MARGIN-BOTTOM: 12pt" class="MsoNormal">I guess your storage rooms, stairs, mechanical rooms, lobbies, etc. should not be </p></div>
<div>
<p class="MsoNormal">On Mon, Nov 1, 2010 at 5:12 AM, James Hansen <<a href="mailto:JHANSEN@ghtltd.com" target="_blank">JHANSEN@ghtltd.com</a>> wrote:</p>
<div>
<div>
<p class="MsoNormal">I was interested to see if anyone would share how they model the exception to G3.1.1 in ASHRAE 90.1-2007 (or 04). This is the part that says when you have a baseline building with system 5-8, you’re supposed to model system 3 or 4 for any spaces that “have occupancy or process loads or schedules that differ significantly from the rest of the building.” It goes on to say that basically the peak thermal loads must differ by 10 Btu / h-ft2 or more from the average of the other spaces, or that schedules must differ by more than 40 full load hours per week, for this exception to apply.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I’ve had reviewers question certain rooms that I’ve put on separate PSZ-AC systems, and so I’ve sort of defaulted to putting almost all rooms on the main systems (5-8). However, in looking at some of my recent models, depending on interior loads and climate, the actual peak cooling load on a square foot basis varies anywhere from 5-20 btu / h-ft2 range for offices. So this means there is a big difference between those models with 5 btu / h-ft2 peak and those with 20. For the models with 5, almost every space in the building is going to be within +/- 10 btu/h-ft2 of that average. However, those buildings that average around 20 will have many rooms that are < 10 btu/h-ft2 peak (ie any internal space whose light + plug load density is < 3.0 W / sq ft).</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><b><span style="COLOR: red">To use a simple example as a question: if your particular office building averaged 20 btuh / h-ft2 peak cooling load, would you model a separate PSZ-AC system for a core bathroom, whose peak cooling load is only 3 btu/h-ft2?</span></b></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">There are lots of rooms where I question whether I should do a separate PSZ-AC/HP system (storage rooms, stairs, mechanical rooms, lobbies, etc). I can see where these meet the 10 Btu/h-ft2 delta exception. </p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">So does everyone really model a bunch of PSZ-AC systems based specifically on the average peak thermal loads of the building?</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">I’m thinking out loud, but if I had an office building that averaged on the low side (5 Btu/h-ft2) for cooling peaks, it seems pretty easy to have a perimeter conference room that exceeded 15 Btu / h-ft2 peak. Seems like an exhaustive process to confirm this delta for every room in a model to determine whether it needs its own system…</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Sorry for the long email. Thanks!</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><b><span style="COLOR: teal">GHT Limited<br></span><span style="COLOR: black">James Hansen, PE, LEED AP</span></b></p>
<p class="MsoNormal"><b><span style="COLOR: black; FONT-SIZE: 10pt">Senior Associate</span></b></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-SIZE: 7.5pt">1010 N. Glebe Rd, Suite 200</span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-SIZE: 7.5pt">Arlington, VA 22201-4749</span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-SIZE: 7.5pt">703-338-5754 (Cell)</span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-SIZE: 7.5pt">703-243-1200 (Office)</span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-SIZE: 7.5pt">703-276-1376 (Fax)</span></p>
<p class="MsoNormal"><span style="COLOR: teal"><a href="http://www.ghtltd.com/" target="_blank"><span style="FONT-SIZE: 10pt">www.ghtltd.com</span></a></span></p>
<p class="MsoNormal"><b><span style="COLOR: #31849b"> </span></b></p>
<p class="MsoNormal"> </p></div></div>
<div style="TEXT-ALIGN: center" class="MsoNormal" align="center"><span style="COLOR: blue; FONT-SIZE: 10pt">
<hr align="center" size="2" width="100%">
</span></div>
<p class="MsoNormal"><span style="COLOR: black; FONT-SIZE: 10pt">The information contained in this communication is confidential, may be privileged, and is intended only for the use of the addressee. It is the property of GHT Limited. Unauthorized use, disclosure or copying of this communication or any part thereof is strictly prohibited and may be unlawful. If you have received this communication in error, please notify me immediately by return e-mail or by e-mail to </span><span style="COLOR: black; FONT-SIZE: 10pt"><a href="mailto:ght@ghtltd.com" target="_blank"><span>ght@ghtltd.com</span></a></span><span style="COLOR: black; FONT-SIZE: 10pt">, and destroy this communication and all copies thereof, including all attachments. Thank you.</span> </p>
<p style="MARGIN-BOTTOM: 12pt" class="MsoNormal"><br>_______________________________________________<br>Bldg-sim mailing list<br><a href="http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org" target="_blank">http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org</a><br>
To unsubscribe from this mailing list send a blank message to <a href="mailto:BLDG-SIM-UNSUBSCRIBE@ONEBUILDING.ORG" target="_blank">BLDG-SIM-UNSUBSCRIBE@ONEBUILDING.ORG</a></p></div>
<p class="MsoNormal"> </p></div></div></div></div>
<div>
<div></div>
<div class="h5">
<p align="left"><font size="2"><font face="Tahoma"><font color="#0000ff">
<hr>
</font></font><font color="#0000ff"><font color="#000000"><font face="Arial">The information contained in this communication is confidential, may be privileged, and is intended only for the use of the addressee. It is the property of GHT Limited. Unauthorized use, disclosure or copying of this communication or any part thereof is strictly prohibited and may be unlawful. If you have received this communication in error, please notify me immediately by return e-mail or by e-mail to </font><a href="mailto:ght@ghtltd.com" target="_blank"><font face="Arial">ght@ghtltd.com</font></a><font face="Arial">, and destroy this communication and all copies thereof, including all attachments. Thank you.</font></font><font color="#000000" face="Tahoma"></font></font></font>
<p></p></p></div></div></blockquote></div><br>