[From nobody Wed Mar 16 13:16:15 2011 Received: from mail.pathfinder-ea.com.pathfinder-ea.com ([10.0.0.250]) by pathfinderengineers.com with Microsoft SMTPSVC(6.0.3790.3959); Wed, 2 Dec 2009 07:38:10 -0500 Received: from frida.dreamhost.com (frida.dreamhost.com [66.33.206.23]) by mail.pathfinder-ea.com.pathfinder-ea.com with ESMTP id 8e364bHRKDcRPb4a; Wed, 02 Dec 2009 07:38:08 -0500 (EST) Received: from diego.dreamhost.com (diego.dreamhost.com [66.33.216.104]) by frida.dreamhost.com (Postfix) with ESMTP id 1C54717E45; Wed, 2 Dec 2009 04:38:08 -0800 (PST) Received: from diego.dreamhost.com (localhost [127.0.0.1]) by diego.dreamhost.com (Postfix) with ESMTP id ECDE74800C; Wed, 2 Dec 2009 04:39:04 -0800 (PST) Received: from mail.pathfinder-ea.com.pathfinder-ea.com (mail.pathfinderengineers.com [64.80.173.82]) by diego.dreamhost.com (Postfix) with ESMTP id 2C96F4800C for <bldg-sim@lists.onebuilding.org>; Wed, 2 Dec 2009 04:39:02 -0800 (PST) Received: from pathfinderengineers.com (pathmail2.pathfinderengineers.com [10.0.0.5]) by mail.pathfinder-ea.com.pathfinder-ea.com with ESMTP id 2jFVVbEwjph8T4Yx for <bldg-sim@lists.onebuilding.org>; Wed, 02 Dec 2009 07:38:02 -0500 (EST) Content-class: urn:content-classes:message Return-Path: <bldg-sim-bounces@lists.onebuilding.org> X-MimeOLE: Produced By Microsoft Exchange V6.5 MIME-Version: 1.0 x-originalarrivaltime: 02 Dec 2009 12:38:10.0770 (UTC) FILETIME=[4EA62320:01CA734C] Content-Type: multipart/alternative; boundary="----_=_NextPart_003_01CA734C.4E30A500" x-virus-scanned: by bsmtpd at pathfinder-ea.com Errors-To: bldg-sim-bounces@lists.onebuilding.org x-barracuda-spam-score: 0.10 X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.2.16099Rule breakdown below pts rule name description---- ---------------------- --------------------------------------------------0.00 HTML_MESSAGE BODY: HTML included in message0.10 BSF_SC0_SA085 Custom Rule SA085 x-barracuda-spam-status: No, SCORE=0.10 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=3.5 KILL_LEVEL=6.0 tests=BSF_SC0_SA085, HTML_MESSAGE x-asg-orig-subj: Re: [Bldg-sim] Why should roofs have high emissivity? x-asg-debug-id: 1259757488-77dc0a3b0001-2xemqW x-barracuda-url: http://spam.pathfinderengineers.com:8000/cgi-mod/mark.cgi X-BeenThere: bldg-sim@lists.onebuilding.org X-Mailman-Version: 2.1.12 X-Original-To: bldg-sim@lists.onebuilding.org List-Post: <mailto:bldg-sim@lists.onebuilding.org> List-Id: Users of building energy simulation tools <bldg-sim-onebuilding.org> List-Archive: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org> x-barracuda-connect: frida.dreamhost.com[66.33.206.23] x-barracuda-start-time: 1259757488 x-barracuda-envelope-from: bldg-sim-bounces@lists.onebuilding.org Subject: Re: [Bldg-sim] Why should roofs have high emissivity? Date: Wed, 2 Dec 2009 08:38:00 -0400 Message-ID: <83996EE70003D04B830E1C4A5E6688CED1449B@PATHMAIL2.pathfinderengineers.com> In-Reply-To: <C73BBE03.7D52%chris@greenengineer.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [Bldg-sim] Why should roofs have high emissivity? Thread-Index: AcpzRTrOj5lq9q4Yr0yQ1bCcwDqlCAABHw4g References: <13d739880912012126m76663329p68e4e7b9525cc19d@mail.gmail.com><C73BBE03.7D52%chris@greenengineer.com> List-Help: <mailto:bldg-sim-request@lists.onebuilding.org?subject=help> List-Subscribe: <http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org>, <mailto:bldg-sim-request@lists.onebuilding.org?subject=subscribe> List-Unsubscribe: <http://lists.onebuilding.org/options.cgi/bldg-sim-onebuilding.org>, <mailto:bldg-sim-request@lists.onebuilding.org?subject=unsubscribe> From: "Bishop, Bill" <wbishop@pathfinder-ea.com> Sender: <bldg-sim-bounces@lists.onebuilding.org> To: <bldg-sim@lists.onebuilding.org> This is a multi-part message in MIME format. ------_=_NextPart_003_01CA734C.4E30A500 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable This message's attachments have been archived by the Barracuda Message = Archiver. ATT110543.txt = <http://ARCHIVER.PATHFINDER-EA.COM:8080/cgi-mod/getstubbedattachment.cgi/= ATT110543.txt?mid=3Dff0fda074f2c08b5bbc6d1e3e71e8e67ea2d62389d719142db8e1= d7b0dc8691fe89f477e&charset=3Diso-8859-1&len=3D241&md5=3Dcb9461702878812d= 53a3abd03c138794> (241) I'll add some general info to the discussion and do a little summing up. =20 LBL has studied emissivity and reflectance and has annual energy impact = results for hot and cold climates: http://eetd.lbl.gov/HeatIsland/CoolRoofs/HeatTransfer/Heating.html =20 The Heat Island Group has a lot of information available pertinent to = the emissivity discussion: http://eetd.lbl.gov/HeatIsland/ =20 We've been focusing on roofs, but window design also has to consider the = same effects. For glazing, we add the property of transmissivity = (radiation passing through the surface) and we have to get more specific = about the types of radiation (solar, visible, UV, infrared) and the = direction (outside vs. inside, as well as angle of incidence). http://www.commercialwindows.umn.edu/issues_energy1.php =20 For opaque building surfaces, such as roofs, walls and window frames, it = is understood that unless stated otherwise: Reflectivity and absorptivity values are for solar radiation. Emissivity values are for thermal/far-infrared radiation. =20 1 - reflectivity =3D absorptivity =20 So when ASHRAE 90.1 Table G3.1 requires you to model a roof reflectivity = of 0.30, you can use an absorptance of 0.70 (such as when modeling in = eQUEST). =20 While there are technical distinctions, the following terms are = generally used interchangeably: Reflectance/reflectivity Absorptance/absorptivity Emittance/emissivity =20 ~Bill =20 William Bishop, EIT, LEED=AE AP | Pathfinder Engineers & Architects LLP Mechanical Engineer =20 134 South Fitzhugh Street Rochester, NY 14608 T: (585) 325-6004 Ext. 114 F: (585) 325-6005 wbishop@pathfinder-ea.com www.pathfinder-ea.com P Please strive to live sustainably. _____ =20 From: bldg-sim-bounces@lists.onebuilding.org = [mailto:bldg-sim-bounces@lists.onebuilding.org] On Behalf Of Christopher = Schaffner Sent: Wednesday, December 02, 2009 6:48 AM To: muehleisen@iit.edu; Chris Jones Cc: bldg-sim@lists.onebuilding.org Subject: Re: [Bldg-sim] Why should roofs have high emissivity? =20 Of course, if your roof is well insulated, it will be covered with snow. = I doubt very much that your "warm" roof will really help much. Go with = the cool roof.=20 -- Chris Schaffner, PE, LEED AP, LEED Faculty(tm) Founder and Principal The Green Engineer, LLP Sustainable Design Consulting 50 Beharrell Street Concord, MA 01742 T: 978.369.8978 M:978.844.1464 chris@greenengineer.com www.greenengineer.com On 12/2/09 12:26 AM, "Ralph Muehleisen" <muehleisen@gmail.com> wrote: Chris makes a good point to consider with cool roofs. A cool roof will indeed reduce solar heat gain to the roof which reduces = its temp (good in summer) and reduces cooling requirements in summer but = will increase heating requirements in the winter. Until someone develops a material where the emissivity changes with = temperature (and not just wavelength) a cool roof that is good in summer = will be bad in winter. So, in colder climates, a cool roof can indeed increase the overall = energy use of a building. Even so, some northern cities like Chicago, mandate cool roofs in = building code. Why? Because the cool roof will reduce the urban heat = island effect where the city has increased temperatures compared to the = surrounding areas. =20 The thought is that the overall benefits of the reduction in urban heat = island effect in summer is more important than the increased energy use = that comes from increased winter cooling load. Ralph Ralph Muehleisen, Ph.D., P.E., LEED AP, FASA Assistant Professor and Director of the Miller Acoustics Lab Civil, Architectural and Environmental Engineering Illinois Institute of Technology Chicago, IL 60616 muehleisen@iit.edu tel: 312-567-3545 fax:312-567-3519 On Tue, Dec 1, 2009 at 6:28 PM, Chris Jones <cj@cr-jay.ca> wrote: In some cases it may be counter productive to use a high emissivity = roof. I have worked on uncooled warehouses where the team used an = approved roofing product to get that point but the heating energy = increased enough to lower the savings enough to lose an EAc1 point. =20 Chris Jones 14 Oneida Avenue Toronto, ON M5J 2E3. Tel. 416-203-7465 Fax. 416-946-1005 _______________________________________________ Bldg-sim mailing list http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org To unsubscribe from this mailing list send a blank message to = BLDG-SIM-UNSUBSCRIBE@ONEBUILDING.ORG =20 _____ =20 _______________________________________________ Bldg-sim mailing list http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org To unsubscribe from this mailing list send a blank message to = BLDG-SIM-UNSUBSCRIBE@ONEBUILDING.ORG ------_=_NextPart_003_01CA734C.4E30A500 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <HTML><HEAD> <META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; = charset=3Diso-8859-1"> <!--Created by Barracuda ExchStub v2.0--> </HEAD><BODY> <TABLE = style=3D"width:100%;background-color:#9099AE;color:white;font-family:Taho= ma;font-size:8pt;"> <COLGROUP><COL width=3D"5"><COL width=3D"10"><COL></COLGROUP> <TR style=3D"padding-top:5px;"><TD><TD colspan=3D"2">This message's = attachments have been archived by the Barracuda Message Archiver.</TR> <TR style=3D"padding-bottom:5px;"><TD><TD><TD><A = href=3D"http://ARCHIVER.PATHFINDER-EA.COM:8080/cgi-mod/getstubbedattachme= nt.cgi/ATT110543.txt?mid=3Dff0fda074f2c08b5bbc6d1e3e71e8e67ea2d62389d7191= 42db8e1d7b0dc8691fe89f477e&charset=3Diso-8859-1&len=3D241&md5=3Dcb9461702= 878812d53a3abd03c138794">ATT110543.txt</A> (241)</SPAN></TR> </TABLE> </BODY></HTML> <html xmlns:v=3D"urn:schemas-microsoft-com:vml" = xmlns:o=3D"urn:schemas-microsoft-com:office:office" = xmlns:w=3D"urn:schemas-microsoft-com:office:word" = xmlns:st1=3D"urn:schemas-microsoft-com:office:smarttags" = xmlns=3D"http://www.w3.org/TR/REC-html40"> <head> <meta name=3DProgId content=3DWord.Document> <meta name=3DGenerator content=3D"Microsoft Word 11"> <meta name=3DOriginator content=3D"Microsoft Word 11"> <link rel=3DFile-List href=3D"cid:filelist.xml@01CA7322.5FF7D440"> <link rel=3DEdit-Time-Data href=3D"cid:editdata.mso"> <!--[if !mso]> <style> v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} </style> <![endif]--> <title>Re: [Bldg-sim] Why should roofs have high emissivity?</title> <o:SmartTagType = namespaceuri=3D"urn:schemas-microsoft-com:office:smarttags" name=3D"place"/> <o:SmartTagType = namespaceuri=3D"urn:schemas-microsoft-com:office:smarttags" name=3D"address"/> <o:SmartTagType = namespaceuri=3D"urn:schemas-microsoft-com:office:smarttags" name=3D"PostalCode"/> <o:SmartTagType = namespaceuri=3D"urn:schemas-microsoft-com:office:smarttags" name=3D"State"/> <o:SmartTagType = namespaceuri=3D"urn:schemas-microsoft-com:office:smarttags" name=3D"City"/> <o:SmartTagType = namespaceuri=3D"urn:schemas-microsoft-com:office:smarttags" name=3D"Street"/> <!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:DoNotRelyOnCSS/> </o:OfficeDocumentSettings> </xml><![endif]--><!--[if gte mso 9]><xml> <w:WordDocument> <w:DontDisplayPageBoundaries/> <w:DisplayBackgroundShape/> <w:SpellingState>Clean</w:SpellingState> <w:GrammarState>Clean</w:GrammarState> <w:DocumentKind>DocumentEmail</w:DocumentKind> <w:EnvelopeVis/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState=3D"false" LatentStyleCount=3D"156"> </w:LatentStyles> </xml><![endif]--><!--[if !mso]> <style> st1\:*{behavior:url(#default#ieooui) } </style> <![endif]--> <style> <!-- /* Font Definitions */ @font-face {font-family:Tahoma; 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font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} </style> <![endif]--> </head> <body lang=3DEN-US link=3Dblue vlink=3Dblue style=3D'tab-interval:.5in'> <div class=3DSection1> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'>I’ll add some general info to = the discussion and do a little summing up.<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'>LBL has studied emissivity and = reflectance and has annual energy impact results for hot and cold = climates:<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'><a href=3D"http://eetd.lbl.gov/HeatIsland/CoolRoofs/HeatTransfer/Heating.htm= l">http://eetd.lbl.gov/HeatIsland/CoolRoofs/HeatTransfer/Heating.html</a>= <o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'>The Heat Island Group has a lot of information available pertinent to the emissivity = discussion:<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'><a = href=3D"http://eetd.lbl.gov/HeatIsland/">http://eetd.lbl.gov/HeatIsland/<= /a><o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'>We’ve been focusing on roofs, = but window design also has to consider the same effects. For glazing, we add the = property of <span class=3DSpellE>transmissivity</span> (radiation passing through = the surface) and we have to get more specific about the types of radiation = (solar, visible, UV, infrared) and the direction (outside vs. inside, as well as = angle of incidence).<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'><a href=3D"http://www.commercialwindows.umn.edu/issues_energy1.php">http://w= ww.commercialwindows.umn.edu/issues_energy1.php</a><o:p></o:p></span></fo= nt></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'>For opaque building surfaces, such = as roofs, walls and window frames, it is understood that unless stated = otherwise:<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'>Reflectivity and <span = class=3DSpellE>absorptivity</span> values are for solar radiation.<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'>Emissivity values are for thermal/far-infrared radiation.<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'>1 – <span = class=3DGramE>reflectivity</span> =3D <span = class=3DSpellE>absorptivity</span><o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'>So when ASHRAE 90.1 Table G3.1 = requires you to model a roof reflectivity of 0.30, you can use an <span = class=3DSpellE>absorptance</span> of 0.70 (such as when modeling in eQUEST).<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'>While there are technical = distinctions, the following terms are generally used = interchangeably:<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'>Reflectance/reflectivity<o:p></o:p><= /span></font></p> <p class=3DMsoNormal><span class=3DSpellE><font size=3D2 color=3Dnavy = face=3DArial><span style=3D'font-size:10.0pt;font-family:Arial;color:navy'>Absorptance/absor= ptivity</span></font></span><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size:10.0pt;font-family:Arial; color:navy'><o:p></o:p></span></font></p> <p class=3DMsoNormal><span class=3DSpellE><font size=3D2 color=3Dnavy = face=3DArial><span style=3D'font-size:10.0pt;font-family:Arial;color:navy'>Emittance</span><= /font></span><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size:10.0pt;font-family:Arial; color:navy'>/emissivity<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'>~Bill<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span = style=3D'font-size: 10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p> <div> <p class=3DMsoNormal><b style=3D'mso-bidi-font-weight:normal'><font = size=3D2 color=3Dblack face=3D"Franklin Gothic Medium"><span = style=3D'font-size:10.0pt; font-family:"Franklin Gothic = Medium";color:black;font-weight:bold;mso-bidi-font-weight: normal;mso-no-proof:yes'>William Bishop, EIT, LEED<sup>®</sup> AP = </span></font></b><b style=3D'mso-bidi-font-weight:normal'><font size=3D2 color=3D"#006600" face=3D"Franklin Gothic Medium"><span = style=3D'font-size:10.0pt;font-family:"Franklin Gothic Medium"; color:#006600;font-weight:bold;mso-bidi-font-weight:normal;mso-no-proof:y= es'>|</span></font></b><b style=3D'mso-bidi-font-weight:normal'><font size=3D2 color=3Dblack face=3D"Franklin Gothic Medium"><span = style=3D'font-size:10.0pt;font-family:"Franklin Gothic Medium"; color:black;font-weight:bold;mso-bidi-font-weight:normal;mso-no-proof:yes= '> </span></font></b><b style=3D'mso-bidi-font-weight:normal'><font size=3D2 color=3Dblack face=3D"Franklin Gothic Medium"><span = style=3D'font-size:10.0pt;mso-bidi-font-size: 12.0pt;font-family:"Franklin Gothic = Medium";color:black;font-weight:bold; mso-bidi-font-weight:normal;mso-no-proof:yes'>Pathfinder Engineers & Architects LLP</span></font></b><b><font size=3D2 color=3Dblack face=3D"Franklin Gothic Medium"><span = style=3D'font-size:10.0pt;font-family:"Franklin Gothic Medium"; color:black;font-weight:bold;mso-no-proof:yes'><o:p></o:p></span></font><= /b></p> <p class=3DMsoNormal><font size=3D1 color=3Dblack face=3DArial><span = style=3D'font-size: 9.0pt;font-family:Arial;color:black;mso-no-proof:yes'>Mechanical = Engineer<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D1 color=3Dblack face=3DArial><span = style=3D'font-size: 5.0pt;font-family:Arial;color:black;mso-no-proof:yes'><o:p> </o:p></= span></font></p> <p class=3DMsoNormal><st1:address w:st=3D"on"><st1:Street = w:st=3D"on"><font size=3D1 color=3Dnavy face=3DArial><span = style=3D'font-size:9.0pt;font-family:Arial; color:navy;mso-no-proof:yes'>134 South Fitzhugh = Street</span></font></st1:Street><font size=3D1 color=3Dnavy><span = style=3D'font-size:9.0pt;color:navy;mso-no-proof:yes'><br> </span></font><st1:City w:st=3D"on"><font size=3D1 color=3Dnavy = face=3DArial><span = style=3D'font-size:9.0pt;font-family:Arial;color:navy;mso-no-proof:yes'>R= ochester</span></font></st1:City><font size=3D1 color=3Dnavy face=3DArial><span = style=3D'font-size:9.0pt;font-family:Arial; color:navy;mso-no-proof:yes'>, <st1:State w:st=3D"on">NY</st1:State> = <st1:PostalCode w:st=3D"on">14608</st1:PostalCode></span></font></st1:address><font = size=3D1 color=3Dnavy><span = style=3D'font-size:9.0pt;color:navy;mso-no-proof:yes'><br> </span></font><font size=3D1 color=3Dnavy face=3DArial><span = style=3D'font-size:9.0pt; font-family:Arial;color:navy;mso-no-proof:yes'>T: (585) 325-6004 = </span></font><font size=3D1 color=3Dblack face=3DArial><span = style=3D'font-size:9.0pt;font-family:Arial; color:black;mso-no-proof:yes'>Ext. 114</span></font><font size=3D1 = color=3Dnavy><span style=3D'font-size:9.0pt;color:navy;mso-no-proof:yes'><br> </span></font><font size=3D1 color=3Dnavy face=3DArial><span = style=3D'font-size:9.0pt; font-family:Arial;color:navy;mso-no-proof:yes'>F: (585) = 325-6005</span></font><font size=3D1 color=3Dblack face=3DArial><span = style=3D'font-size:9.0pt;mso-bidi-font-size: 12.0pt;font-family:Arial;color:black;mso-no-proof:yes'><o:p></o:p></span>= </font></p> <p class=3DMsoNormal><font size=3D1 color=3Dblack face=3DArial><span = style=3D'font-size: 9.0pt;font-family:Arial;color:black;mso-no-proof:yes'>wbishop@pathfinder-= ea.com<o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D1 color=3Dblack face=3DArial><span = style=3D'font-size: 9.0pt;mso-bidi-font-size:12.0pt;font-family:Arial;color:black;mso-no-proo= f: yes'>www.pathfinder-ea.com</span></font><font color=3Dnavy><span style=3D'color:navy;mso-no-proof:yes'><o:p></o:p></span></font></p> <p class=3DMsoNormal><font size=3D5 color=3Dgreen face=3DWebdings><span style=3D'font-size:18.0pt;font-family:Webdings;mso-bidi-font-family:Webdi= ngs; color:green;mso-no-proof:yes'>P</span></font><font color=3Dgreen><span style=3D'color:green;mso-no-proof:yes'> </span></font><font size=3D1 = color=3Dgreen><span style=3D'font-size:7.5pt;color:green;mso-no-proof:yes'>Please strive to = live sustainably.</span></font><font color=3Dgreen><span = style=3D'color:green'><o:p></o:p></span></font></p> </div> <div> <div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font = size=3D3 face=3D"Times New Roman"><span style=3D'font-size:12.0pt'> <hr size=3D2 width=3D"100%" align=3Dcenter tabindex=3D-1> </span></font></div> <p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span = style=3D'font-size:10.0pt; font-family:Tahoma;font-weight:bold'>From:</span></font></b><font = size=3D2 face=3DTahoma><span style=3D'font-size:10.0pt;font-family:Tahoma'> bldg-sim-bounces@lists.onebuilding.org [mailto:bldg-sim-bounces@lists.onebuilding.org] <b><span = style=3D'font-weight: bold'>On Behalf Of </span></b>Christopher Schaffner<br> <b><span style=3D'font-weight:bold'>Sent:</span></b> Wednesday, December = 02, 2009 6:48 AM<br> <b><span style=3D'font-weight:bold'>To:</span></b> muehleisen@iit.edu; = Chris Jones<br> <b><span style=3D'font-weight:bold'>Cc:</span></b> = bldg-sim@lists.onebuilding.org<br> <b><span style=3D'font-weight:bold'>Subject:</span></b> Re: [Bldg-sim] = Why should roofs have high emissivity?</span></font><o:p></o:p></p> </div> <p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span = style=3D'font-size: 12.0pt'><o:p> </o:p></span></font></p> <p class=3DMsoNormal style=3D'margin-bottom:12.0pt'><font size=3D2 = face=3DVerdana><span style=3D'font-size:11.0pt;font-family:Verdana'>Of course, if your roof = is well insulated, it will be covered with snow. I doubt very much that your “warm” roof will really help much. Go with the cool roof. = <br> <br> --<br> <br> Chris Schaffner, PE, LEED AP, LEED Faculty™<br> Founder and Principal<br> <br> The Green Engineer, LLP<br> Sustainable Design Consulting<br> <st1:Street w:st=3D"on"><st1:address w:st=3D"on">50 Beharrell = Street</st1:address></st1:Street><br> <st1:place w:st=3D"on"><st1:City w:st=3D"on">Concord</st1:City>, = <st1:State w:st=3D"on">MA</st1:State> <st1:PostalCode w:st=3D"on">01742</st1:PostalCode></st1:place><br> T: 978.369.8978<br> M:978.844.1464<br> <a href=3D"chris@greenengineer.com">chris@greenengineer.com</a><br> www.greenengineer.com<br> <br> <br> On 12/2/09 12:26 AM, "Ralph Muehleisen" <<a href=3D"muehleisen@gmail.com">muehleisen@gmail.com</a>> = wrote:</span></font><o:p></o:p></p> <p class=3DMsoNormal><font size=3D2 face=3DVerdana><span = style=3D'font-size:11.0pt; font-family:Verdana'>Chris makes a good point to consider with cool = roofs.<br> <br> A cool roof will indeed reduce solar heat gain to the roof which reduces = its temp (good in summer) and reduces cooling requirements in summer but = will increase heating requirements in the winter.<br> <br> Until someone develops a material where the emissivity changes with = temperature (and not just wavelength) a cool roof that is good in summer will be bad = in winter.<br> <br> So, in colder climates, a cool roof can indeed increase the overall = energy use of a building.<br> <br> Even so, some northern cities like <st1:City w:st=3D"on"><st1:place = w:st=3D"on">Chicago</st1:place></st1:City>, mandate cool roofs in building code.  Why?  Because the cool = roof will reduce the urban heat island effect where the city has increased temperatures compared to the surrounding areas.  <br> <br> The thought is that the overall benefits of the  reduction in urban = heat island effect in summer is more important than the increased energy use = that comes from increased winter cooling load.<br> <br> <br> Ralph<br> <br> Ralph Muehleisen, Ph.D., P.E., LEED AP, FASA<br> Assistant Professor and Director of the Miller Acoustics Lab<br> Civil, Architectural and Environmental Engineering<br> Illinois Institute of Technology<br> <st1:place w:st=3D"on"><st1:City w:st=3D"on">Chicago</st1:City>, = <st1:State w:st=3D"on">IL</st1:State> <st1:PostalCode w:st=3D"on">60616</st1:PostalCode></st1:place><br> <a href=3D"muehleisen@iit.edu">muehleisen@iit.edu</a><br> tel: 312-567-3545  fax:312-567-3519<br> <br> <br> On Tue, Dec 1, 2009 at 6:28 PM, Chris Jones <<a = href=3D"cj@cr-jay.ca">cj@cr-jay.ca</a>> wrote:</span></font><o:p></o:p></p> <p class=3DMsoNormal style=3D'margin-bottom:12.0pt'><font size=3D2 = face=3DVerdana><span style=3D'font-size:11.0pt;font-family:Verdana'>In some cases it may be = counter productive to use a high emissivity roof.  I have worked on = uncooled warehouses where the team used an approved roofing product to get that = point but the heating energy increased enough to lower the savings enough to = lose an EAc1 point.  <br> <br> <br> <br> <br> <br> <br> Chris Jones<br> <st1:Street w:st=3D"on"><st1:address w:st=3D"on">14 Oneida = Avenue</st1:address></st1:Street><br> <st1:place w:st=3D"on"><st1:City w:st=3D"on">Toronto</st1:City>, = <st1:State w:st=3D"on">ON</st1:State> <st1:PostalCode w:st=3D"on">M5J 2E3</st1:PostalCode></st1:place>.<br> Tel.  416-203-7465<br> Fax. 416-946-1005<br> <br> <br> _______________________________________________<br> Bldg-sim mailing list<br> <a = href=3D"http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.or= g">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=3D"BLDG-SIM-UNSUBSCRIBE@ONEBUILDING.ORG">BLDG-SIM-UNSUBSCRIBE@ONEBUI= LDING.ORG</a></span></font><o:p></o:p></p> <p class=3DMsoNormal style=3D'margin-bottom:12.0pt'><font size=3D2 = face=3DVerdana><span style=3D'font-size:11.0pt;font-family:Verdana'><o:p> </o:p></span></= font></p> <div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font = size=3D2 face=3DVerdana><span style=3D'font-size:11.0pt;font-family:Verdana'> <hr size=3D3 width=3D"95%" align=3Dcenter> </span></font></div> <p class=3DMsoNormal><font size=3D2 face=3DVerdana><span = style=3D'font-size:10.0pt; font-family:Verdana'>_______________________________________________<br> Bldg-sim mailing list<br> <a = href=3D"http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.or= g">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=3D"BLDG-SIM-UNSUBSCRIBE@ONEBUILDING.ORG">BLDG-SIM-UNSUBSCRIBE@ONEBUI= LDING.ORG</a></span></font><o:p></o:p></p> </div> </body> </html> ------_=_NextPart_003_01CA734C.4E30A500-- ]