The truly cost-efficient features, however, are the systems Mr. Weingarten uses to power and heat the house. Electricity is drawn from six photovoltaic solar panels on the roof, each producing 105 watts, which power the lights, the computer and some other appliances. The solar panels — along with a 1920s propane stove in the kitchen — have allowed Mr. Weingarten to go completely off the utility grid. So while a home the size of his has an average monthly electric bill of $80 and a gas bill averaging $55, according to Keely Wachs, a spokesman for Pacific Gas and Electric, the local energy company, Mr. Weingarten pays nothing to the utility.

He does, however, spend $43 a month to cover the propane he uses to power the stove, refrigerator, clothes dryer and water heater, and to pay for the gasoline to power his backup generator, which charges the solar batteries on days when there is not enough sunshine — not infrequent, given the thick fog that can sometimes roll over this coastal area. (He turns the generator on so rarely, he said, that he used only about 25 gallons of gasoline in 2006.)

To heat the house, Mr. Weingarten combined solar energy with two much older approaches: radiant heating and gravity circulation. Two solar-powered pumps in the basement circulate a freezeproof mixture of water and vodka through solar thermal panels on the roof. (He said he uses vodka rather than an industrial antifreeze because, among other things, it’s more efficient and is nontoxic.) The mixture is heated to between 80 and 140 degrees, depending on the weather, and then flows down to a copper coil at the bottom of a 1,000-gallon tank in the basement, where it heats water in the tank.

Image Mr. Weingarten used steel and rebar in this staircase. Credit... Terrence McCarthy for The New York Times

A separate gravity-assisted system heats the house by way of copper tubing that starts in a coil at the top of the tank. As the tank water heats up, Mr. Weingarten explained, water in this coil is also heated, and rises, passing through an elaborate system of tubing in the walls. As the water loses its heat, it falls back to the coil in the storage tank, heats up and rises again, repeating the process.

To ensure that the heat generated this way stays inside, the walls were built nearly twice as thick — eight inches — as those in most houses, and like the floors and ceilings, were made of foam-core structural insulated panels, Mr. Weingarten said. “In the winter, even a little bit of sun is enough to keep the heat going in the water tank,” he said. “As long as there’s 80-degree water in the tank, I can keep the house at 70 degrees.” He acknowledged that in the winter he supplements the system with a wood-burning stove, because his wife feels chilly at 70 degrees.

Since the heat is solar-generated and the wood is free, Mr. Weingarten’s heating bill is virtually zero. All told, he said, his energy expenditures average $43 a month, for the propane and gasoline.