A frequent traveler, who lives alone in Washington DC (T 13.2 C, T 12

A frequent traveler, who lives alone in Washington DC (T̅ ≅ 13.2 ^◦C, ΔT ≅ 12 ^◦C), is away from home every other week throughout the year. Normally she keeps her thermostat at 20 ^◦C, and turns it down to 10 ^◦C when she is away. Estimate her fractional savings in heating energy first ignoring the need to reheat her home upon return. Then estimate the correction for reheating. Take A_H = 100 m² and C_H = 10 MJ/K, and assume that she has insulated her home so that R_H = 2.1 m² K/W.