Answer
$0.270375 kWh$ of energy is required the heat the air in the house.
Work Step by Step
Use the equation $q=mcΔT$, where q represents the heat that flows into a system to increase its temperature, m represents the mass of the substance, 'c' represents the heat capacity of the substance and ΔT represents the change in temperature.
Since the temperature changes from $7^{\circ}C to 28^{\circ}C$, the $\Delta T = 28^{\circ}C-7^{\circ}C = 21^{\circ}C$
$q=mcΔT$
$q= (45000 g)\times(\frac{1.03 J}{g\times^{\circ}C})\times 21^{\circ}C = 973350 Joules$
Lastly we must convert the heat unit from J to kWh by dividing by $3.6\times10^{6} J $ because $1 kWh=3.6\times10^{6} J $ so $973350 Joules \div 3.6\times10^{6} J= 0.270375 kWh.$
