Example $2$: A wood$-$framing singly$-$family detached residence in Denver, $CO$ has a corner room with eastfacing windows. The fixed windows are regular double glass with a total area of $25\mathrm{.}5sqft.$ Determine the cooling attribute for the following windows type if the outside design temperature is $90F$ :

$($a$)$ Window with no inside shading.

$($b$)$ Window with fully drawn venetian blinds.