Packaged Terminal AC (PTAC) cooling efficiencies are based on direct expansion air conditioning, but are typically limited to a Seasonal Energy Efficiency Ratio (SEER) of 12. Heating efficiencies rely on electrical resistance, heat pump, boiler, or furnace efficiencies. Boiler or furnace PTACs will be less expensive to operate than heat pump or electric resistance PTACs. If fuel-fired heat is not feasible, heat pump PTACs are more efficient and less expensive to operate than electric resistance PTACs. Occupancy control can be used to reduce demand, either centrally or within each room.