Replacing incandescent lights with energy -efficient fluorescent lights can reduce the lighting energy consumption to one-fourth of what it was before. The energy consumed by the lamps is eventually converted to heat, and thus switching to energy-efficient lighting also reduces the cooling load in summer but increases the heating load in winter. Considering a building that is heated by a natural gas furnace with an efficiency of 80 percent and cooled by an air conditioner with a COP of 3.5. Electricity costs $0.12/kWh and natural gas costs $1.40/therm (1 therm =105,500 kJ). If originally the building with incandescent lights consumes 1 KW for lighting and the operation time is 10 hours/day, determine the variation of daily energy cost of the building (a) in summer and (b) in winter after switching to fluorescent lights