* T+ I' g, @$ a. t. e
3 Y }% K6 Q$ a& N7 }' @0 m) q# l6 c
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. 0 \/ n( p, \; r: L1 e. P8 p2 t5 W: C7 A
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.