<div dir="ltr">Hi camila,<div><br></div><div>i am not sure about this fully may be any senior person here can guide you better. i just want to share my experience with u. TRNSYS actually calculate heat transfer coefficient during simulation after every time interval on the basis of the material's properties, does not use constant value during whole simulation period. its value is dependent on outside and inside of building weather conditions. external and internal convective heat transfer coefficient( that are input values). my suggestion is to ignore and try to validate your computed and experimental results by comparing. in my case i confirm overall heat transfer coefficient manually by using following equation..</div><div><br></div><div> U-value (overall heat transfer coefficient) = Q/ A(Ti - To)</div><div><br></div><div><span style="font-size:12pt;line-height:107%;font-family:"times new roman",serif">Q is heat losses through the wall you want to check( select form layer output in TRNBuild), A area of the wall, Ti and To inside and outside temperatures. so u can calculate U-value for each time period. hope this will work.</span></div><div><span style="font-size:12pt;line-height:107%;font-family:"times new roman",serif"><br></span></div><div><span style="font-size:12pt;line-height:107%;font-family:"times new roman",serif">Please let me know if you get some other information about this.</span></div><div><span style="font-size:12pt;line-height:107%;font-family:"times new roman",serif"><br></span></div><div><span style="font-size:12pt;line-height:107%;font-family:"times new roman",serif">Regards </span><br></div><span style="font-size:12pt;line-height:107%;font-family:calibri,sans-serif"><span id="gmail-_x0000_t75">
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</span></span></span><br></div><div>adnan </div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Jan 18, 2017 at 8:40 AM, Camila Davila Valdebenito via TRNSYS-users <span dir="ltr"><<a href="mailto:trnsys-users@lists.onebuilding.org" target="_blank">trnsys-users@lists.onebuilding.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi TRNSYS users!<br>
I'm simulating a building and I need to create a massless layer. I've calculate the overall heat transfer coefficient that I need for some "X" wall (6.6581 W/m2K in this case). The massless layer requires a thermal resistance in [hm2K/kJ], which is the reciprocal of the heat transfer coefficient. Doing this, I get R=0.0417203 [m2Kh/kJ].<br>
When I create a wall with this layer (and this R value) the wall type manager shows me an U value of 3.123 [W/m2K] (totaly diferent of the one that I need).<br>
Does anyone knows how TRNSYS calculate this? or what is the right unit conversion?<br>
Thanks for your time<br>
<br>
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