QUESTION $1$

A rectangular $($flat roof$)$ standalone storage facility has dimensions $20$ m by $10$ m $.$ Its height is $4$ m $.$ The facility is to be maintained at $20C$ for an outside design temperature of $-2C.$

$($a$)$ Calculate the required heat input to the facility given the thermal properties of its components in the table below.

$[15$ marks$]$

$($b$)$ On the basis of the calculated design heat load $($from part $($a$)),$ if the actual demand is equivalent to this design load for exactly $2,200$ hours per annum, which of the following two systems has a lower annual running cost $($using simple non discounting calculation$)$ to deliver this heat demand?

$($i$)$ An Electrical Heat Pump with a COP of $3.$

$($ii$)$ A Gas Boiler with an efficiency of $80\%.$

$[5$ marks$]$

Data:

All walls, roof and floor can be taken to be external components.

Doors can be taken as $2\%$ of the total wall area and windows can be taken as $10\%$ of the total wall area.

Air infiltration from outside to inside is at a rate of $0\mathrm{.}5$ air changes per hour.

$Cp=1200\frac{J}{m^3}K$

Electricity cost $=35\frac{c}{k}Wh$

Gas cost $=20\frac{c}{k}Wh$

$\backslash$table$[[\backslash$table$[[$Buildings$],[$Component$]],\backslash$table$[[$U$-$value $($Thermal$],[$Transmittance