A house has a composite wall of plaster board (Lp = 10mm, k=0.72 W/m.K), fibre glass insulation (Lb=100mm, k=1.4 W/m.K), and plywood (Lp = 20mm, k=0.12 W/m.K), as indicated in the sketch. On a cold winter day the convection heat transfer coefficients are h0 = 60 W/m2.K and hi = 30 W/m2.K. The total wall surface area is 350 m2.
Inside kp kp ks Outside
hi,T∞,i =200C ho,T∞,o =-150C
(a) Determine a symbolic expression for the total thermal resistance of wall, including inside and outside convection effects for prescribed conditions.
(b) Determine the total heat loss through the wall.
(c) If the wind were blowing violently, raising ho to 300 W/m2.K. Determine the percentage increase in the heat loss