Balancing heating demand.
A few years ago I spent some time in Scotland (great food, wonderful place, and really nice people, the single malt was good too). They had what they called "storage heaters." At that time, the electric rates were higher in the daytime than at night, which seemed like a good idea to me. In order to take advantage of lower night rates, and help balence the daytime and night demands for power, they ran the heat only at night. A storage heater looked like an electric resistance radiator. It contained electric resistence coils at the bottom of a tall, shallow box, and the upper part was filled with bricks. The coils would turn on and cook the bricks all night long, and in the morning the power would turn off and the bricks would radiate the heat all day, finally cooling off in the evening in time for the power to switch on again. To regulate the heat, you could adjust how long the power was on (adjustments were not instantanious this way). Another way was a shutter atop the heater which could be closed to trap heat inside, slowing the cooling of the bricks, and releasing less heat into the room. If you got too cold and the shutter was open, you would put on a sweater, a cheap, fast, and easy solution!
In the US, the most efficient heating and cooling system I have ever seen is a geothermal heat pump. They are godaweful expensive to install (nearly twice the cost of a conventional HVAC system), but the operating costs, maintainance costs, and system-longevity make it well worth every penny. In this type of system, there are pipes, which are either buried horizontally, or drilled vertically, into the ground. It relies on the ground temperature being nearly constant year-round. The system pumps coolant, or even water, through the pipes and into the "furnace" in the building. The result is a comfortable building that is also very cheap to operate. There is no ugly, noisy, AC compressor outside, just a small, quiet, and easily hidden pump. There are geothermal heat pumps that are over 50 years old, still in use and, still energy-efficient. Why can't we just use these more regularly?
Cursing my conventional AC bill,
Dave