<div>This is described in the Engineering Reference (<a href="http://apps1.eere.energy.gov/buildings/energyplus/pdfs/engineeringreference.pdf">http://apps1.eere.energy.gov/buildings/energyplus/pdfs/engineeringreference.pdf</a>) beginning on page 133 of the PDF (page number 89).</div>
<div> </div>
<div>It depends on the moisture of the soil, plant cover, air temperature, rainfall, etc.<br><br></div>
<div class="gmail_quote">On Tue, Jul 13, 2010 at 11:21 AM, Chris Jones <span dir="ltr"><<a href="mailto:cj@enersave.ca">cj@enersave.ca</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">
<div>I am wondering how EnergyPlus handles the effect of saturated soil in insulation value; especially in winter when the damp/wet soil would be frozen. I am interested mostly in heating loads.<br><br><br>At 07:26 PM 6/26/2010, Drury B Crawley wrote:<br>
<blockquote type="cite">From the EnergyPlus Input-Output Reference, the fields describing the green roof top layer include:<br>
<dl>
<dd>Height of Plants {m}<br>
<dd>Leaf Area Index {dimensionless}<br>
<dd>Leaf Reflectivity {dimensionless}<br>
<dd>Leaf Emissivity<br>
<dd>Minimum Stomatal Resistance (s/m)<br>
<dd> <br>
<dd>(this is on page 183 of the IORef PDF (page number 144): <a href="http://apps1.eere.energy.gov/buildings/energyplus/pdfs/inputoutputreference.pdf" target="_blank">http://apps1.eere.energy.gov/buildings/energyplus/pdfs/inputoutputreference.pdf</a> )<br>
<br></dd></dd></dd></dd></dd></dd></dd></dl> <br>The Engineering Reference describes the equations beginning on page 114 of the PDF (page number 90): <br><a href="http://apps1.eere.energy.gov/buildings/energyplus/pdfs/engineeringreference.pdf" target="_blank">http://apps1.eere.energy.gov/buildings/energyplus/pdfs/engineeringreference.pdf</a> <br>
<br> <br> <br>On Fri, Jun 25, 2010 at 10:41 AM, Nick Caton <<a href="mailto:ncaton@smithboucher.com" target="_blank">ncaton@smithboucher.com</a> > wrote: <br> <br>
<dl><br>
<dd>Open question:<br><br>
<dd> <br><br>
<dd>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.<br><br>
<dd> <br><br>
<dd>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…<br>
<br>
<dd> <br><br>
<dd>~Nick<br><br>
<dd> <br><br>
<dd> <br><br>
<dd>NICK CATON, E.I.T.<br><br>
<dd>PROJECT ENGINEER<br><br>
<dd>25501 west valley parkway<br><br>
<dd>olathe ks 66061<br><br>
<dd>direct 913 344.0036<br><br>
<dd>fax 913 345.0617<br><br>
<dd>Check out our new web-site @ <a href="http://www.smithboucher.com/" target="_blank">www.smithboucher.com</a> <br><br>
<dd> <br><br>
<dd>From: <a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a> [<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank"> mailto:bldg-sim-bounces@lists.onebuilding.org</a>] On Behalf Of Drury B Crawley <br>
<dd>Sent: Friday, June 25, 2010 9:25 AM <br>
<dd>To: <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a><br>
<dd>Subject: [Bldg-sim] Modeling a Green Roof<br><br>
<dd> <br><br>
<dd>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><br>
<br>
<dd> <br>
<dd> <br><br>
<dd>---------- Forwarded message ---------- <br>
<dd>From: Jeremy Poling <<a href="mailto:jpoling@epsteinglobal.com" target="_blank"> jpoling@epsteinglobal.com</a>><br>
<dd>Date: Fri, Jun 25, 2010 at 10:04 AM<br>
<dd>Subject: Re: [Bldg-sim] Modeling a Green Roof<br>
<dd>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><br>
<dd> <br>
<dd> <br><br>
<dd>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.<br>
<br>
<dd> <br><br>
<dd>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.<br>
<br>
<dd> <br><br>
<dd>JEREMY R. POLING, PE, LEED AP <br>
<dd>Associate Vice President,<br><br>
<dd>Senior Sustainability Analyst <br>
<dd>Strategic Services<br>
<dd>Site Solutions | Operations | Sustainability<br>
<dd> <br>
<dd>EPSTEIN<br>
<dd> <br>
<dd>Epstein is a firm believer in sustainability. We ask that you please consider the environment before printing this e-mail.<br><br>
<dd> <br><br>
<dd>From: <a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a> [<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank"> mailto:bldg-sim-bounces@lists.onebuilding.org</a>] On Behalf Of Fareed Syed <br>
<dd>Sent: Friday, June 25, 2010 8:05 AM<br>
<dd>To: Jason Boehning; <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a><br>
<dd>Subject: Re: [Bldg-sim] Modeling a Green Roof<br><br>
<dd> <br><br>
<dd>I heard from our director of sustainability to use R-5 for a typical green roof. It was confirmed by few senior architects.<br><br>
<dd> <br><br>
<dd>Thanks,<br><br>
<dd> <br><br>
<dd>Fareed<br><br>
<dd> <br><br>
<dd>From: <a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a> [<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank"> mailto:bldg-sim-bounces@lists.onebuilding.org</a>] On Behalf Of Jason Boehning <br>
<dd>Sent: Friday, June 25, 2010 8:46 AM<br>
<dd>To: <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a><br>
<dd>Subject: [Bldg-sim] Modeling a Green Roof<br><br>
<dd> <br><br>
<dd>Howdy! <br><br>
<dd> <br><br>
<dd>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.<br>
<br>
<dd> <br><br>
<dd> <br><br>
<dd>Jason Boehning, EIT<br><br>
<dd>Mechanical Engineer<br><br></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd>
</dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dd></dl>Error! Filename not specified.<br><br>6161 Savoy, Suite 1212<br>
<br>Houston, Texas 77036<br><br> <br><br> v. 713.482.2322<br><br> f. 713.482.2314<br><br> e. <a href="mailto:Jason.Boehning@ricegardner.com" target="_blank">Jason.Boehning@ricegardner.com</a><br><br> <br><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><br>
<br> <br> <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></blockquote>
<p><br>Chris Jones<br>14 Oneida Avenue<br>Toronto, ON M5J 2E3.<br>Tel. 416-203-7465<br>Fax. 416-946-1005<br><br></p></div></blockquote></div><br>