Dear luckygrass,<br><br><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="ProgId" content="Word.Document"><meta name="Generator" content="Microsoft Word 11"><meta name="Originator" content="Microsoft Word 11"><link rel="File-List" href="file:///C:%5CDOCUME%7E1%5Cdebora%5CCONFIG%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"><style>  </style> <p class="MsoNormal"><span style="" lang="EN-GB">I have read your comments on espr-list, sorry I’m not an ESPr user, but what is necessary to say is if you are considering that the U value has really no sense on a transient simulation, because external temperatures are varying, and so the ventilation inside the gap of the double skin. You could in same way “fool the code” (I don’t know how to do it in espr because I’m not an user) but if it is possible you could impose constant temperatures (outside and inside) and obtain the heat flux through the façade, then divide by the temperature difference, and you”ll get an U value. </span></p> <p class="MsoNormal"><span style="" lang="EN-GB">Other way, could be, simulating some hours or a day, and postprocessing for each instant, the heat flux through the façade, dividing by the difference temperature for that instant. In this way, you will obtain a series of U values, and you could obtain the mean. </span></p> <p class="MsoNormal"><span style="" lang="EN-GB">But you”ll see that if you consider night and day, the results of U value will be disappointing (because the transient conditions impose than during night and day the results will be different and the mean has no sense) May be you could try the same calculation, with central hours of a summer and winter day, and obtain data relevant for you. </span></p> <p class="MsoNormal"><span style="" lang="EN-GB">I have calculated some U values for double facades, with a transient code, imposing constant conditions, with the only intention of comparing with other U values, but I repeat this value has no sense on a transient simulation.</span></p> <p class="MsoNormal"><span style="" lang="EN-GB"> </span></p> <p class="MsoNormal"><span style="" lang="EN-GB">I hope I could help you.</span></p> <p class="MsoNormal"><span style="" lang="EN-GB"> </span></p> <p class="MsoNormal"><span style="" lang="EN-GB">;-)</span></p> <br><br><br><div class="gmail_quote">2010/5/16 Achim Geissler <span dir="ltr"><<a href="mailto:achim.geissler@intergga.ch">achim.geissler@intergga.ch</a>></span><br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> <div style="word-wrap: break-word;">Dear Daisy (?)<div><br></div><div>that all the said values are zero is strange. I just checked the results of a double facade model and e.g. conduction(inside) is not zero for the glass surfaces both facing the zone and the facade gap. Which save level are you using? 4?</div> <div><br></div><div>Also, WIS calculates U-values for double facades both unventilated and ventilated (based on the approach described in ISO 15099). So, as "facade description", this may suffice.</div><div><br> </div><div>For the combination "building and facade", it is tricky. Any loads reported by ESP-r take storage effects into account, also. So it will be very difficult if not impossible to derive a meaningful U-value for a double facade (loads, gains, losses across two or more zones) from the results given. Additionally, all the convective heat transfer coefficients in ESP-r are not the same as used in standard U-value calculation by default. </div> <div><br></div><div>However, in my experience, the facade must be described by the standard numbers (non-transient U-value, g-value) anyway, so a contractor can deliver to those numbers. Which values are most beneficial to the system "building" must be derived from the overall model based on loads and / or comfort criteria results from ESP-r. Going back and forth, one could optimize the facade parameters to meet the building situation in this way and have a "contractor-ready" description of the facade parameters to hand.</div> <div><br></div><div>Best</div><div>Achim</div><div><br></div><div><br></div><div><br><div><div><div></div><div class="h5"><div>On May 16, 2010, at 3:15 AM, 王菊花 wrote:</div><br></div></div><blockquote type="cite"><span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><div style="font-size: 10pt; font-family: Verdana;"> <div><div></div><div class="h5"><font size="4" face="Arial">Dear Achim,</font><br><font face="Arial"><font style="font-size: 16pt;" size="4"> I am sorry I have't expressed my minds clearly.I know there is no straightforward way to calculate U-value,which is exactly what I mean.So I want to find an easy way to do that,<span style="font-size: 12pt;">U=Q/<span style="font-size: 12pt;">⊿T.Q is the heat conduction of the double-skin facade.<span style="font-size: 12pt;">⊿T is the temperature difference of interior and exterior surfaces.As you say,using a simple tool like WIS can calculate U value.But there are many openings for the exterior glass of double-skin facade in my model,so there is ventilation between the air gap and environment.I realize this by building zones for the air gap area and flow connections for the openings.I try to use<i><font color="#ff0000"><span> </span>result analysis ></font><font color="#ff0000">surface fluxes></font></i><span> </span><font color="#ff0000"><i>conduction(inside)<span> </span><font color="#000000">or</font> conduction(other face)<span> </span></i></font><font color="#000000">facility in esp-r,the output results are</font><font color="#000000"><span> </span>all zero.Maybe it is not practical to calculate U value in this way,I thought out another way to do this.I can use WINDOW5.0 to calculate U value of double-skin facade without ventilation,then campare loads of double-skin facade with and without ventilation in esp-r,divide the load difference by<span> </span><span style="font-size: 12pt;">⊿T.Suppose the result is<span> </span><span style="font-size: 12pt;">⊿U,then plus<span> </span><span style="font-size: 12pt;">⊿U with U value of double-skin facade without ventilation.Does the final result make sense?Anxiously expecting your kind answers.Many thanks.</span></span></span></font></span></span></span></font></font><br> <br> <br> <br> <br> <br><hr>CC:<span> </span><a href="mailto:esp-r@lists.strath.ac.uk" target="_blank">esp-r@lists.strath.ac.uk</a><br>From:<span> </span><a href="mailto:achim.geissler@intergga.ch" target="_blank">achim.geissler@intergga.ch</a><br> To:<span> </span><a href="mailto:luckygrass100@hotmail.com" target="_blank">luckygrass100@hotmail.com</a><br>Subject: Re: [esp-r] surface fluxes<br>Date: Sat, 15 May 2010 19:20:29 +0200<br><br>Hi <div><br></div><div>not sure what you mean. What turned out zero? All the values in the res-variables you name? Or your subsequent calculations? Anyway, there is no straightforward way to extract the U-value (if that is what you mean with comprehensive transfer coefficient) of a double facade construction. </div> <div><br></div><div>I would recommend using a simple tool like WIS to compare your window / facade constructions in regard to basic parameters (g-value, U-value). And look at overall loads to compare the impact on the building as a system.</div> <div><br></div><div>Regards</div><div>Achim</div><div><br></div><div><br><div><div>On May 15, 2010, at 1:31 PM, 王菊花 wrote:</div><br><blockquote><span style="word-spacing: 0px; text-transform: none; color: rgb(0, 0, 0); text-indent: 0px; white-space: normal; letter-spacing: normal; border-collapse: separate;"><div style="font-size: 10pt; font-family: Verdana;"> Dear Dear all，<br> I am puzzled again.I am simulating an low-carbon building with double-skin facade for the south facade.I need calculate out the comprehensive transfer coefficient h(W/m2.K),then compare it with that of normal single window.I was thinking maybe I can output the temperature and heat conduction of the interior and exterior surfaces.But when I used the<span> </span><i><font color="#ff0000">surface fluxes</font></i><span> </span>facility,and choosed<span> </span><font color="#ff0000"><i>conduction(inside)<span> </span><font color="#000000">or</font> conduction(other face),</i></font><font color="#000000">it turned out all zero.Why?</font><br> </div></span></blockquote></div></div><br><hr>更多热辣资讯尽在新版MSN首页！<span> </span><a href="http://cn.msn.com/" target="_blank">立刻访问！</a><span> </span><br><hr></div></div>使用Messenger保护盾2.0，支持多账号登录！<span> </span><a href="http://www.windowslive.cn/safe/" target="_blank">现在就下载！</a><span> </span>_______________________________________________<br> esp-r mailing list<div class="im"><br><a href="mailto:esp-r@lists.strath.ac.uk" target="_blank">esp-r@lists.strath.ac.uk</a><br></div><a href="http://lists.strath.ac.uk/mailman/listinfo/esp-r" target="_blank">http://lists.strath.ac.uk/mailman/listinfo/esp-r</a></div> </span></blockquote></div><br><font color="#888888"><div> <span style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"><div style="word-wrap: break-word;"> <div><a href="mailto:achim.geissler@intergga.ch" target="_blank">achim.geissler@intergga.ch</a></div><div><br></div><div><br></div></div></span><br> </div><br></font></div></div><br>_______________________________________________<br> esp-r mailing list<br> <a href="mailto:esp-r@lists.strath.ac.uk">esp-r@lists.strath.ac.uk</a><br> <a href="http://lists.strath.ac.uk/mailman/listinfo/esp-r" target="_blank">http://lists.strath.ac.uk/mailman/listinfo/esp-r</a><br></blockquote></div><br><br clear="all"><br>-- <br>Débora Faggembauu<br><br>