If there was some way of circulating air in the basement like the furnace does it would possibly to be more efficient by using heatpumps. Here in the North the house units give off heat till 0 deg F and then electricity kicks in. I have used the fireplace running most of the time and the Furnace kicking in at a lower setting and it worked well in heating the Basement. Most of the time the outside temperature fell below 32F the furnace had to supplement the fireplace. The fireplace has no waist of heat like the 40,000BTU Propane furnace that I have in my unit. I did the calculation and 30Lbs of propane would last 11 Hrs if the furnace would run none stop. This fall the propane use was 30Lbs per week, I was satisfied with the consumtion, considering it was under freezing most of the time for 3 weeks. I was using Electricity from my house that is tax deductible because I have 2 Heated Appartments in the house.