<div>Hi All,</div> <div> </div> <div>I have a very simple problem. You know that for energy efficiency issues, the thermophysical properties of the materials that composed the envelope of building is very essential. In order to evaluate the amount of heat transfer from one side of the wall to other, t <span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"><font size="2">he most common reference is "R-value," or <i>resistance</i> to heat flow. The higher the R-value of a material, the better it is at resisting heat loss (or heat gain). the arithmathically reverse of R-value is <span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"> <font size="2">U-factor (or "U-value," as it is often called) which is a measure of the flow of heat—thermal transmittance—through a material, given a difference in temperature on either side. In short, for simple energy calculations we can guess that the lower u-value, the lower energy consumption. However the mass of the materials have very essential role during heat transfer even the u-value is constant. High mass materials (the specific heat and density of the materials show us the heat capacity of the materials, the high mass materials have high heat capacity) have special characteristics which are called time lag and degrement factor. Simply degrement factor reduces the peak loads and time lag delays the peak loads from one side of the wall to other. (for further information: <a href="http://www.buildinggreen.com/auth/article.cfm?fileName=070401a.xml">http://www.buildinggreen.com/auth/article.cfm?fileName=070401a.xml</a> ) </font></span></font></span></div> <div><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"> <font size="2">Anyhow, I have a research on sensitivity analysis of the energy performance and one of the parameters that I evaluate is the effect of thermal mass. I have wall construction -from outside to inside-composed of plaster (2cm), insulation (PUR)(2cm), aerated concrete (20cm), plaster (2cm) and the u-value is 0.48 W/m2K. The specific heat of aerated concrete that I used is 840 J/kgK and the density is 500 kg/m3. I replaced aerated concrete with heavy mix concrete which has specific heat of 1000J/kgK and density of 2400 kg/m3. In order to make u-value constant (it should be constant otherwise I can not see the effect of thermal mass alone) I changed the dimension of concrete from 20cm to 30cm and insulation from 2cm to 6cm. Thus the u-value stays constant ( 0.48W/m2K) Now, I made the simulations (rest of the input parameters for both of the model is completely same). However heating energy calculated for aerated concrete is 3792.65 kWh, heavy mix concrete is 3781.27kWh. It is very interesting for me and I go one step further and use water as a wall construction. Water has a specific heat of 4180 J/kgK. Esp-r warned me that this value is too high but made the calculations. However the result is very close to the others, 3791.02 kWh. I checked the surface temperatures and heat storage as well but these are the same or very very close to each other.</font></span></span></div> <div><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"> <font size="2">Probably I miss a step which is necessary to activate the effect of thermal mass. I also tried to use "define uncertanities" option of esp-r but I need a password to activate it....</font></span></span> </div> <div><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"> <font size="2">Is there anyone to help me?</font></span></span></div> <div><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"> <font size="2"></font></span></span> </div> <div><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"> <font size="2">Thanks in advance...</font></span></span></div> <div><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"> <font size="2"></font></span></span> </div> <div><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"><span style="FONT-SIZE: 12pt; COLOR: black; FONT-FAMILY: Helvetica; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA"> <font size="2">Gulsu</font></span></span></div>