9 S% x8 T$ d+ K$ f- | o" t % K& Y L/ m( @$ B我家的房子,冬天上午, 太阳足的时候,自然达到25度。 房子02年的。I did upgrade the ceiliing insulation from R20 to R60 though. 3 d# X5 u* N' O3 e. T. j* w. d : i O0 i! K d) e8 {5 x( X9 T
40% is lost from ceilling. 40% from windows. so 屋顶改进分别对保温性能贡献大. Costed me $2000, because I used the Pink insulation ( usually for walls) at the ceiling. If you use foam that usually for ceilling, then your cost should be only 1/3 of mine. Rent a foam spreader from HomeDepot.