<div>From the EnergyPlus Input-Output Reference, the fields describing the green roof top layer include:</div>
<blockquote style="MARGIN-RIGHT: 0px" dir="ltr">
<div>Height of Plants {m}</div>
<div>Leaf Area Index {dimensionless}</div>
<div>Leaf Reflectivity {dimensionless}</div>
<div>Leaf Emissivity</div>
<div>Minimum Stomatal Resistance (s/m)</div>
<div> </div>
<div>(this is on page 183 of the IORef PDF (page number 144): <a href="http://apps1.eere.energy.gov/buildings/energyplus/pdfs/inputoutputreference.pdf">http://apps1.eere.energy.gov/buildings/energyplus/pdfs/inputoutputreference.pdf</a>)</div>
</blockquote>
<div> </div>
<div>The Engineering Reference describes the equations beginning on page 114 of the PDF (page number 90): </div>
<div><a href="http://apps1.eere.energy.gov/buildings/energyplus/pdfs/engineeringreference.pdf">http://apps1.eere.energy.gov/buildings/energyplus/pdfs/engineeringreference.pdf</a></div>
<div> </div>
<div> </div>
<div> </div>
<div class="gmail_quote">On Fri, Jun 25, 2010 at 10:41 AM, Nick Caton <span dir="ltr"><<a href="mailto:ncaton@smithboucher.com">ncaton@smithboucher.com</a>></span> wrote:
<div> </div>
<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">Open question:</span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt"> </span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt">I’ve ascribed to the “tack an R / thermal mass value onto a new layer” approach in the past… but would appreciate a more nuanced approach if it could be done quickly enough.</span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt"> </span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt">I’m curious: Does EnergyPlus or any other option/model out there account the variable shading effects of the foliage on the roof construction, as a user might define it? I’ve speculated this element could be handled relatively simply in eQuest using a geometrically adjacent shading surface with an annual fractional schedule, but eQuest (to my experience) doesn’t have a clean approach to account for the varying thermal mass and insulative properties of soil that varies in moisture over time…</span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt"> </span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt">~Nick</span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt"> </span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 11pt"><img alt="cid:489575314@22072009-0ABB" width="119" height="37"></span><b><span style="COLOR: #2d4d5e; FONT-SIZE: 11pt"></span></b></p>
<p class="MsoNormal"><b><span style="COLOR: #2d4d5e; FONT-SIZE: 11pt"> </span></b></p>
<p class="MsoNormal"><b><span style="COLOR: #2d4d5e; FONT-SIZE: 11pt">NICK CATON, E.I.T.</span></b><b><span style="COLOR: #2d4d5e"></span></b></p>
<p class="MsoNormal"><span style="COLOR: #cc9900; FONT-SIZE: 7.5pt">PROJECT ENGINEER</span><span style="COLOR: #cc9900; FONT-SIZE: 7.5pt"></span></p>
<p class="MsoNormal"><span style="COLOR: #2d4d5e; FONT-SIZE: 10pt">25501 west valley parkway</span></p>
<p class="MsoNormal"><span style="COLOR: #2d4d5e; FONT-SIZE: 10pt">olathe ks 66061</span></p>
<p class="MsoNormal"><span style="COLOR: #2d4d5e; FONT-SIZE: 10pt">direct 913 344.0036</span></p>
<p class="MsoNormal"><span style="COLOR: #2d4d5e; FONT-SIZE: 10pt">fax 913 345.0617</span></p>
<p class="MsoNormal"><i><span style="COLOR: #2d4d5e; FONT-SIZE: 10pt">Check out our new web-site @ </span></i><span style="COLOR: #1f497d; FONT-SIZE: 11pt"><a title="blocked::www.smithboucher.com" href="http://www.smithboucher.com/" target="_blank"><span style="FONT-SIZE: 10pt">www.smithboucher.com</span></a></span><u><span style="COLOR: blue; FONT-SIZE: 10pt"> </span></u><span style="COLOR: #1f497d; FONT-SIZE: 11pt"></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"> <a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a> [mailto:<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Drury B Crawley
<div><b>Sent:</b> Friday, June 25, 2010 9:25 AM </div>
<div>
<div></div>
<div class="h5">
<div><b>To:</b> <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a></div>
<div><b>Subject:</b> [Bldg-sim] Modeling a Green Roof</div></div></div></span>
<p></p></p></div>
<div>
<div></div>
<div class="h5">
<p class="MsoNormal"> </p>
<div>
<p class="MsoNormal">EnergyPlus has a model for green roofs built in -- based on experimental measurements and experience of researchers at Portland State University, Prof David Sailor: <a href="http://web.cecs.pdx.edu/~sailor/" target="_blank">http://web.cecs.pdx.edu/~sailor/</a></p>
</div>
<div>
<p class="MsoNormal">
<div> </div>
<div> </div></p></div></div></div>
<div>
<div>
<div></div>
<div class="h5">
<p style="MARGIN-BOTTOM: 12pt" class="MsoNormal">---------- Forwarded message ----------
<div>From: <b>Jeremy Poling</b> <<a href="mailto:jpoling@epsteinglobal.com" target="_blank">jpoling@epsteinglobal.com</a>></div>
<div>Date: Fri, Jun 25, 2010 at 10:04 AM</div>
<div>Subject: Re: [Bldg-sim] Modeling a Green Roof</div>
<div>To: <a href="mailto:Jason.Boehning@ricegardner.com" target="_blank">Jason.Boehning@ricegardner.com</a>, <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a></div>
<div> </div>
<div> </div></p></div></div>
<div>
<div>
<div>
<div></div>
<div class="h5">
<p class="MsoNormal"><span style="FONT-SIZE: 10pt">Penn State University (<a href="http://horticulture.psu.edu/cms/greenroofcenter/" target="_blank">http://horticulture.psu.edu/cms/greenroofcenter/</a>) and Michigan State University (<a href="http://www.hrt.msu.edu/greenroof/" target="_blank">http://www.hrt.msu.edu/greenroof/</a>) both have significant research programs on green roofs. I would recommend looking at the results of the Penn State study on energy transfer in Green Roofs (<a href="http://etda.libraries.psu.edu/theses/approved/WorldWideFiles/ETD-4616/Thesis_Paulo_Tabares_revised.pdf" target="_blank">http://etda.libraries.psu.edu/theses/approved/WorldWideFiles/ETD-4616/Thesis_Paulo_Tabares_revised.pdf</a>). In general, green roofs handle energy through the insulating effects of soil, the cooling effects of evapotranspiration in the plants, and water flows within the green roof assembly. This means that a calculated R-value will be different depending on the amount of plant material participating in evapotranspiration, the wetness of the soil, and whether the roof is intensive or extensive. A straight R-value approach is very simplified and should be used with the understanding that model results are much less likely to be accurate. The Penn State study gives a review of published literature showing extensive green roofs have R-values between 1.8 and 4.8 while intensive green roofs have R-values between 5 and 20.</span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 10pt"> </span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 10pt">In general, the average R-value of soil is 0.25 per inch, so for a 12” soil depth the R-value of the soil would be R-3 excluding assumptions on soil wetness and evapotranspiration. We typically go conservative and just model the R-value of the additional soil since you would need a TRNSYS or MatLab model to take into account the other energy benefits of a green roof.</span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 10pt"> </span></p>
<div>
<p class="MsoNormal"><b><span style="COLOR: #c75b12; FONT-SIZE: 10pt">JEREMY R. POLING, PE, LEED AP</span></b><span style="FONT-SIZE: 10pt">
<div></div></span><span style="COLOR: gray; FONT-SIZE: 8pt">Associate Vice President,</span></p></div>
<p class="MsoNormal"><span style="COLOR: gray; FONT-SIZE: 8pt">Senior Sustainability Analyst
<div>Strategic Services</div>
<div><i>Site Solutions | Operations | Sustainability</i></div></span><span style="FONT-SIZE: 10pt"></span></p></div><span style="FONT-SIZE: 10pt">
<div> </div>
<div><b><span style="COLOR: #c75b12">EPSTEIN</span></b></div>
<div></div></span><span style="FONT-SIZE: 8pt"> </span></div><span style="FONT-SIZE: 8pt">
<div><b><i><span style="COLOR: green">Epstein is a firm believer in sustainability. We ask that you please consider the environment before printing this e-mail.</span></i></b></div></span></div></div>
<p class="MsoNormal"><span style="FONT-SIZE: 10pt"> </span></p>
<div>
<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"> <a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a> [mailto:<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Fareed Syed
<div><b>Sent:</b> Friday, June 25, 2010 8:05 AM</div>
<div><b>To:</b> Jason Boehning; <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a></div>
<div><b>Subject:</b> Re: [Bldg-sim] Modeling a Green Roof</div></span></p></div></div></div>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 10pt">I heard from our director of sustainability to use R-5 for a typical green roof. It was confirmed by few senior architects.</span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 10pt"> </span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 10pt">Thanks,</span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 10pt"> </span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 10pt">Fareed</span></p>
<p class="MsoNormal"><span style="COLOR: #1f497d; FONT-SIZE: 10pt"> </span></p>
<div>
<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"> <a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a> [mailto:<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Jason Boehning
<div><b>Sent:</b> Friday, June 25, 2010 8:46 AM</div>
<div><b>To:</b> <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a></div>
<div><b>Subject:</b> [Bldg-sim] Modeling a Green Roof</div></span></p></div></div></div>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="FONT-SIZE: 10pt">Howdy! </span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 10pt"> </span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 10pt">Has anyone modeled a green roof? I have a standard roof with 12 inches of soil and grass. I have been searching the web for thermal properties such as U values, thermal absorptivity and so on. Are there any good references to find these values or does anyone have tips to model a green roof? I appreciate your help.</span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 10pt"> </span></p>
<p class="MsoNormal"><span style="FONT-SIZE: 10pt"> </span></p>
<p>Jason Boehning, EIT</p>
<p>Mechanical Engineer</p></div></blockquote></div>
<p><b>Error! Filename not specified.</b></p>
<div class="im">
<p>6161 Savoy, Suite 1212</p>
<p class="MsoNormal">Houston, Texas 77036</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"> v. 713.482.2322</p>
<p class="MsoNormal"> f. 713.482.2314</p>
<p class="MsoNormal"> e. <a href="mailto:Jason.Boehning@ricegardner.com" target="_blank"><span style="COLOR: windowtext">Jason.Boehning@ricegardner.com</span></a></p>
<p class="MsoNormal"> </p></div>
<div class="im">
<p style="MARGIN-BOTTOM: 12pt" class="MsoNormal">
<div>_______________________________________________</div>
<div>Bldg-sim mailing list</div>
<div><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></div>
<div>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></div></p></div>
<p class="MsoNormal"> </p>
<div> </div>