Question $2$

Consider a single$-$storey rectangular retail store in Toronto, with dimensions of $80m($width$)$ x $125m($length$)$ x $12m($height$),$ with the long axis exposed to the south. The store sits on a slab$-$on$-$grade of R$-5,$ it has a $($low slope$)$ flat commercial compact roof of R$-20$ and the walls are face$-$sealed exterior insulation and finishing system $($EIFS$)$ of R$-30.$

a$.$ Accounting for solar radiation incident on building surfaces and assuming an average air leakage under normal conditions of $0\mathrm{.}5$ACH, find the heating power demand when the ambient air temperature is $T_{\text{o}\text{u}\text{t}}=-20$degC at solar noon $($You are welcome to assume that east, west and north fa$$ades do not receive any direct sunlight during solar noon$).$ Assume no snow accumulation.

b$.$ The retailer considers installing flat skylights on the roof to bring some daylight into the building core, as research indicates that it can increase sales. Using triple glazed low$-$e skylights of $U-0\mathrm{.}13$ with solar heat gain coefficient of $SHGC=0\mathrm{.}6,$ estimate the area of the skylights required to reduce the heating power demand by $20\%$ at solar

noon, when compared to $($a$).$ Assume that the solar irradiance incident on the skylight surface is $Q_{\text{s}\text{o}\text{l}\text{a}\text{r}}=1000\frac{W}{m^2},$ at solar noon.