I’ve tried it all: caulking cracks, blowing in insulation, replacing drafty windows and–I’m especially proud of this one–installing a mail-slot cover so airtight it could be used in a space shuttle docking module . Yet my home heating bill remains an object of fear and loathing. After years of trying low-tech solutions, I’m drawn to a high-tech solution, and the one I keep hearing about is the geothermal heat pump.

Heat pumps, of whatever variety, give you the giddy feeling of breaking the laws of physics. The gas boiler in my basement is 80 percent efficient; burning gas unavoidably heats the exhaust gases as well as the water for the radiators. An electric heater is almost 100 percent efficient. But a heat pump can be more than 100 percent efficient. A 1000-watt electric heater emits 3400 BTU of heat in an hour, but the same amount of electricity, used to run a heat pump, might transfer 15000 BTU of heat into the house.