If you have a room $(12**8**4m)$ and you have $2$ solar windows $($the dimension of the window $(2\mathrm{.}5**2m))$ located in the largest wall and the solar gain of them $1\mathrm{.}3k\frac{w}{d}ay$ and you have a door $(1\mathrm{.}6**2\mathrm{.}5m)$ in the northern wall and the temperature inside $=21C$ and the average temperature outside $=8C$ and the natural air change $=1\mathrm{.}8$ time $/$hour$/$day and the characteristics of materials are shown in the table below

$\backslash$table$[[$Elements$,U$ value$],[$Window$,1\mathrm{.}8\frac{W}{m^2}*K$