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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Comic Sans MS";color:#1F497D;mso-fareast-language:EN-US">Hi Dr. Tachon,
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Comic Sans MS";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Comic Sans MS";color:#1F497D;mso-fareast-language:EN-US">The U-Wert means how your wall transfer the heat and it’s normal that you get this change because you changed the thickness
of your materials as well as his type (U-wert= Thermal conductivity/thickness). You may also consider your ground-on-slab as boundary wall by setting to the inside (front) and outside (back) convective heat transfer coefficients. You can refer to volume,
page 143 of the documentation<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-family:"Arial",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><i><span lang="EN-US" style="font-size:11.0pt;font-family:"Arial",sans-serif;mso-fareast-language:EN-US">“</span></i><i><span lang="EN-US" style="font-size:11.0pt">WALLS WITH KNOWN BOUNDARY CONDITION<o:p></o:p></span></i></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><i><span lang="EN-US" style="font-size:11.0pt">A wall having a known boundary condition might be a concrete floor resting on ground of a known temperature or a wall adjacent to a zone whose temperature is known. The front of the wall is
considered to be at the inside of the zone. Normally, the boundary condition is the temperature of a node connected to the back surface of the wall through a pure resistance. It is possible to specify the surface temperature of the outside by setting the back
side heat transfer coefficient of the WALL Type (HBACK) to a very small value (<b>less than 0.001 kJ/h/m²).</b> This WALL Type is then only appropriate for use as a wall with a known boundary. The use of a very small value may be confusing but was kept for
backwards compatibility reasons”<o:p></o:p></span></i></p>
<p class="MsoNormal"><i><span lang="EN-US"><o:p> </o:p></span></i></p>
<p class="MsoNormal"><i><span lang="EN-US" style="font-size:11.0pt;font-family:"Comic Sans MS";color:#1F4E79">I Hope that’s helps
<o:p></o:p></span></i></p>
<p class="MsoNormal"><i><span lang="EN-US" style="font-size:11.0pt;font-family:"Comic Sans MS";color:#1F4E79">Hassan
</span></i><i><span lang="EN-US" style="font-size:10.0pt;font-family:"Comic Sans MS";color:#1F4E79;mso-fareast-language:EN-US"><o:p></o:p></span></i></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Arial",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Arial",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black">Dr. Hassan Mahach</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black">wissenschaftlicher Mitarbeiter<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black">Arbeitsfeld Technische Innovationen<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black">+49 681 844 972 23<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black">mahach@izes.de<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black">www.izes.de<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Calibri",sans-serif;color:black">IZES gGmbH | Altenkesseler Straße 17, Geb. A1 | 66115 Saarbrücken<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Calibri",sans-serif;color:black">Büro Berlin | Albrechtstraße 22 | 10117 Berlin<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Calibri",sans-serif;color:black">Telefon: +49 681 844 972 0 | Fax: +49 681 761 799 9<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Calibri",sans-serif;color:black">Rechtsform: gGmbH | Registergericht Saarbrücken HRB 8499<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Calibri",sans-serif;color:black">Steuernummer: 040 140 241 53 | USt.-IdNr.: DE 138 113 796<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Calibri",sans-serif;color:black">Aufsichtsratsvorsitz: Minister Jürgen Barke<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Calibri",sans-serif;color:black">Geschäftsführung: Prof. Frank Baur | Dr. Lesya Matiyuk<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Calibri",sans-serif;color:black"><img width="394" height="74" id="Grafik_x0020_1" src="cid:image001.jpg@01D8905B.2921E320" alt="cid:image001.jpg@01D8905B.2921E320"></span><span style="font-size:9.0pt;font-family:"Calibri",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Von:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> TRNSYS-users [mailto:trnsys-users-bounces@lists.onebuilding.org]
<b>Im Auftrag von </b>Loic Tachon via TRNSYS-users<br>
<b>Gesendet:</b> Dienstag, 5. Juli 2022 09:38<br>
<b>An:</b> TRNSYS users mailing list at OneBuilding.org <trnsys-users@lists.onebuilding.org><br>
<b>Cc:</b> Loic Tachon <dr.loic.tachon@gmail.com><br>
<b>Betreff:</b> [TRNSYS-users] TRNSYS ground floor<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Dear users,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I want to simulate a huge building (5500 m2) with a 20 cm concrete ground without isolation. <o:p></o:p></p>
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<p class="MsoNormal">I don't really understand how the direct contact boundary condition works.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I made a ground wall composed of 20 cm of concret and 80 cm of calcar.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I realize that the simulation result (Tzone temperature) is very dependent of the ground temperature boundary condition. <o:p></o:p></p>
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<p class="MsoNormal">I use type 77 with the depth of ground temperature of 1m, the amplitude of 12 and the mean temperature of 12.<o:p></o:p></p>
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<p class="MsoNormal">If I change the parameters of type 77, the zone temperature results change a lots.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">In the inf file, i get u value result of my floor : THERMAL CONDUCTANCE, U= 4.21086 kJ/h m2K; U-Wert= 0.97567 W/m2K<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">If I don't put the 80 cm of calcar, I get the following u value :<o:p></o:p></p>
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<p class="MsoNormal">THERMAL CONDUCTANCE, U= 37.80000 kJ/h m2K; U-Wert= 3.77020 W/m2K<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Is this normal ? What means U-Wert ?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><br clear="all">
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:9.5pt;color:black">Dr. Loïc Tachon </span></b><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:9.5pt;color:black">(+33) 6 7440-0536 (France)</span><span style="font-size:9.5pt"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.5pt"><o:p> </o:p></span></p>
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