“Computational Civil Engineering - "Intersections" International Journal

160 R. Rotbergwhere the thermal transmittance, U, is calculated with U=1/R, R being the thermalresistence ;The decrement factor is always less than 1.4. EXAMPLES OF APPLICATIONThe dynamic thermal characteristics of the closing elements were determinedunder harmonic boundary conditions for one day period, corresponding to dailymeteorological variation and temperature setback.Thermophysical characteristics of the materials used in the closing elements are:a) for homogeneous elements:Brick masonry wall (the thickness, d = 0,36 m) ;- the thermal conductivity, λ = 0,8 W/mK ;- the specific heat capacity, c = 0,87 KJ/KgK ;- the density, ρ = 1800 Kg/m 3The four elements of the transfer matrix Z are :Z 11 = -10.395 + 1.08i Z 12 = 0.686-0.847iZ 21 = 77.172+62.529i Z 22 = -10.395 + 1.08iTaking account of surface resistances of 0,13 W/(m 2 K) inside and 0,04W/(m 2 K) outside, the transfer matrix of the wall is:Z 11 = -13.482 -1.421i Z 12 = 2.855-0.705iZ 21 = 77.172+62.529i Z 22 = -20.428 – 7.049iDecrement factor, f = 0.211, thermal transmittance U = 1.613 W/(m 2 K)Table1 Dynamic characteristics of the homogenous elementthermal admittancemodulus time shiftinternal side (Y 1 ) 4.611 W/(m 2 K) -10.679 hexternal side (Y 2 ) 7.349 W/(m 2 K) -9.811 hareic heat capacitiesinternal side (C 1 ) 6.343 (J/K) -external side (C 2 ) 10.111 (J/K) -