A small studio suite in $6-$storey multi$-$unit residential building in Vancouver has an area of $35$ m$2,$ with envelope

wall area of $5$ m$2.$ The suite has a heat recovery ventilation $($HRV$)$ that supplies$/$exhausts $14$ L$/$s of balanced

ventilation. Air from a slightly pressurized corridor enters the suite through gaps around its main door at a rate

of $2$ L$/$s$.$ The building is airtight and compartmentalized, so the stack effect is neglected. The prevailing winter

ambient$/$outdoor conditions are $=4$C$,$ and $=90\%.$ The suite indoor temperature is maintained at $=$

$22$C$.$ The corridor is maintained at $=20$C$,$ and $=60\%.$ The HRV supply air temperature is $=15$C $($heat

exchanger pre$-$warms the outdoor air before being supplied to the suite$).$ The moisture generation rate by the

occupants is $0\mathrm{.}35$ kg$/$h$.$

a$)$ Calculate the relative humidity of the air supplied by the HRV$.$

b$)$ Calculate the relative humidity at the suite. Note that the air and moisture balance equations need to

consider the exfiltration of indoor air through the envelope.

c$)$ Calculate the minimum window temperature to eliminate the risk of condensation under these

conditions.