Example$2$Link Figure $1\mathrm{.}1$ shows a simplified vertical section through a building $30$m long consisting of offices and stores separated by a corridor. The offices are maintained at $21$oC and the stores at $5$oC when the ambient air temperature is $-5$oC$.$ The corridor is unheated. The ventilation is from ambient to the offices, from the offices to the corridor, and from the corridor to ambient. There is negligible flow of air between the corridor and the store. Using the data given calculate; $($i$)$ the temperature in the corridor $($ii$)$ the heat input required for the offices $($iii$)$ the heat input required for the stores