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<p class=MsoNormal>I have two suggestions for you:<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span
style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>Use the GreenSave Life-Cycle Cost Benefit Calculator (<a
href="http://www.tremcoroofing.com/greensave.asp">http://www.tremcoroofing.com/greensave.asp</a>)
found on Tremco’s website. Tremco is a roofing company. They
provide an on-line tool that calculates the life-cycle cost of green roofs.
It explains the energy savings methodology briefly and gives resources.<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span
style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'>
</span></span><![endif]>Use DesignBuilder (interface for EnergyPlus; <a
href="http://www.designbuilder.co.uk/">http://www.designbuilder.co.uk/</a>) or
EnergyPlus directly (<a href="http://energyplus.gov/">http://energyplus.gov/</a>).
The newest release of DesignBuilder, Version 2, now has the capability of
modeling Green Roofs. If you go their “new functionality”
page and click on “Green roofs” link, it will give you a more
detailed description of the modeling methodology. DesignBuilder also
allows you to account for irrigation control of the green roof and
precipitation (entered into the model separately from the weather file).<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Hope this helps! Good luck. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Here is an excerpt from the GreenSave site:<o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'>Annual
Savings/sq.ft. of Roof Area</span></b><span style='font-size:12.0pt;font-family:
"Times New Roman","serif"'><o:p></o:p></span></p>
<table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0>
<tr>
<td style='padding:0in 0in 0in 0in'>
<p class=MsoNormal align=center style='text-align:center'><b><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'>City<o:p></o:p></span></b></p>
</td>
<td style='padding:0in 0in 0in 0in'>
<p class=MsoNormal align=center style='text-align:center'><b><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'>Heating<br>
(therms/sq.ft.)<o:p></o:p></span></b></p>
</td>
<td style='padding:0in 0in 0in 0in'>
<p class=MsoNormal align=center style='text-align:center'><b><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'>Cooling+Fans<br>
(kWh/sq.ft.)<o:p></o:p></span></b></p>
</td>
</tr>
<tr>
<td style='padding:0in 0in 0in 0in'>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>Phoenix,
AZ<o:p></o:p></span></p>
</td>
<td style='padding:0in 0in 0in 0in'>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>0.016<o:p></o:p></span></p>
</td>
<td style='padding:0in 0in 0in 0in'>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>0.41<o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style='padding:0in 0in 0in 0in'>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>Washington,
DC<o:p></o:p></span></p>
</td>
<td style='padding:0in 0in 0in 0in'>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>0.020<o:p></o:p></span></p>
</td>
<td style='padding:0in 0in 0in 0in'>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>0.29<o:p></o:p></span></p>
</td>
</tr>
<tr>
<td style='padding:0in 0in 0in 0in'>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>Portland,
OR<o:p></o:p></span></p>
</td>
<td style='padding:0in 0in 0in 0in'>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>0.020<o:p></o:p></span></p>
</td>
<td style='padding:0in 0in 0in 0in'>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>0.25<o:p></o:p></span></p>
</td>
</tr>
</table>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'>Source: Allen
Lee, Quntec LLC<o:p></o:p></span></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'>Annual energy
savings for three different cities for a “typical” green roof on a
single story building. Savings estimates per sq.ft. of roof are fairly constant
with building height, though they vary a moderate amount for heating energy.
The analysis assumes natural gas heating and electric cooling.<o:p></o:p></span></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'>Other studies
have indicated a 1% decrease in heating energy and a 6% decrease in cooling
energy associated with green roofs.<o:p></o:p></span></p>
<p class=MsoNormal><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"'>Alex
Chapin, E.I.T., LEED AP</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Energy
Engineer</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>2rw
Consultants</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>T:
434-296-2116 ext. 101</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>F:
434-977-1862</span><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoPlainText>From: "Nathan Miller"
<nathanm@rushingco.com><o:p></o:p></p>
<p class=MsoPlainText>Subject: Re: [Bldg-sim] Modelling an eco-roof / green
roof<o:p></o:p></p>
<p class=MsoPlainText>To: "'Erin Rowe'" <Erowe@peci.org>, <bldg-sim@lists.onebuilding.org><o:p></o:p></p>
<p class=MsoPlainText>Message-ID: <00d101c9d7e3$4fdf44b0$ef9dce10$@com><o:p></o:p></p>
<p class=MsoPlainText>Content-Type: text/plain; charset="us-ascii"<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>I assume you are referring to so-called green roofs, that
is vegetated roofs. I too am in the NW, and have been asked several times about
whether we can take credit in the energy model for the benefits of a green
roof. I have usually erred on the side of caution, and advised that we not
claim benefit. <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText> <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>This is partially due to the fact that when you most want
the additional R-value that the growth media might provide, during the winter,
the soil is most likely to be saturated with water and provide the least
insulative value. There obviously will still be some benefit compared to a bare
roof, but it would be pretty hard to quantify. There would also be great
variability in the effect depending the depth of the media, is it in trays or
directly on the roof, etc. <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText> <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>I suppose that if you intend on watering the roof during
the summer the evapo-transpiration might help keep the roof area cooler and
result in lower cooling loads, though again, that would be difficult to
quantify. <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText> <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>I'd be interested if others out there have found some
reputable data on energy advantages to green roofs. Otherwise, I'd stick with
the stormwater and habitat benefits they provide as a selling point. <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText> <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Nathan Miller<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Senior Energy Engineer/Mechanical Engineer<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>direct: 206.788.4577<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>fax: 206.285.7111 <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>From: bldg-sim-bounces@lists.onebuilding.org<o:p></o:p></p>
<p class=MsoPlainText>[mailto:bldg-sim-bounces@lists.onebuilding.org] On Behalf
Of Erin Rowe<o:p></o:p></p>
<p class=MsoPlainText>Sent: Monday, May 18, 2009 10:58 AM<o:p></o:p></p>
<p class=MsoPlainText>To: bldg-sim@lists.onebuilding.org<o:p></o:p></p>
<p class=MsoPlainText>Subject: [Bldg-sim] Modelling an eco-roof / green roof<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText> <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>I was wondering if anyone has any recommendations on how
to model an eco-roof. How are the U-values / R-values determined?
Are there any standards referenced or typical assumptions made? Are there
substantial energy savings associated with a eco-roof?<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>I've read a few studies that claim that there are and are
not significant energy savings associated with an eco-roof, and I was under the
impression that the major benefit of an eco-roof is storm water mitigation and
possible sewage savings. I was hoping that the bldg-sim group can shed
some light on this topic. The projects I'm working on are typically in the
Pacific NW, where I would think the energy savings associated with this
technology would be minimal since the climate is fairly temperate. I would
appreciate any thoughts you might have on this technology, it's associated
energy savings and modelling assumptions.<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Thanks, <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Erin <o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
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