$1.$ Compare the U value for a typical brick wall from a $1900$s era house to a modern home.

Assume the brick wall is $550$mm thick with brick having a conductivity of kbrick $=1\mathrm{.}5$ W$/$m K$.$

Assume the modern wall consists of $15$mm render $($krender $=0\mathrm{.}18$ W$/$m K$),215$mm of aerated

brick $($kair brick $=0\mathrm{.}14$ W$/$m K$)$ & $30$mm of insulation $($kinsulation $=0\mathrm{.}026$ W$/$m K$).$ In both cases

there$$s an internal and external resistance factor of $0\mathrm{.}1$ m$2$

$.$K$/$W and $0\mathrm{.}04$ m$2$

$.$K$/$W

respectively