A $0\mathrm{.}5m1m$ double paned window is made of two

silica glass panes $1$ cm thick, with air in between.

Under steady conditions, linear $($constant gradient$)$

temperature profiles are found in both silica panes, as

well as the air. If the room $($and the inner surface of

the inner glass pane$)$ is at a temperature of $25C,$ while

outdoors it is $-25C$ with a convection coefficient of

$18W{m}^{-2}{K}^{-1},$ what is the rate of heat loss through the

window? What is the rate of heat loss if the room

temperature is decreased to $20C?$ Finally, what is the

rate of heat loss for a room temperature of $25C,$ but

with one of the panes $($and the air$)$ removed?