A dormitory at a large university, built 50 years ago, has exterior walls constructed of L5 = 25-mm-thick sheathing with a thermal conductivity of k3 = 0. 1 W/m. K. To reduce heat losses in the winter, the university decides to encapsulate the entire dormitory by applying an Li = 25-mm-thick layer of extruded insulation characterized by ki = 0. 029 W/m K to the exterior of the original sheathing. The extruded insulation is, in turn, covered with an Lg = 5-mm-thick architectural glass with kg = 1. 4 W/m. K. Determine the heat flux through the original and retrofitted walls when the interior and exterior air temperatures are Tinfity, i = 22 degree C and Tinfity, 0 = -20 degree C, respectively. The inner and outer convection heat transfer coefficients are hi = 5 W/m2 K and h0 = 25 W/m2 K. respectively.