EXAMPLE $5-3$

A basement house measures $8\mathrm{.}5m$ wide and $12m$ long and is $2\mathrm{.}5m$ high from basement ceiling to floor. The top $1\mathrm{.}6m$ of the wall is above grade. The wall consists of the following layers:

$($i$)200mm$ concrete.

$($ii$)25mm$ of polystyrene board