Superefficient boilers

Here's the house's basement, with the solar hot water tanks on the left and very efficient natural gas boilers on the right. The gas boilers operate at 96 percent efficiency and work with temperature sensors outside to optimize their performance.

The solar hot water tanks will help the boilers operate more efficiently as well. Rooftop solar panels heat water stored in the two tanks. When the boiler turns on, it will draw from the hot water tanks to reduce the heat needed from the boiler.