Make Your House a Perfect Zero

For some, the phrase "off the grid" may still conjure up visions of a weather-beaten wood shack with rusted metal on the outside and angry tax evaders within. But that's about change, if two Texas-based architects have anything to do with it.


The Austin American Statesman reported this month that after ten years in the making, architects Scott Specht and Louise Harpman have a plan for a net-zero house that is "shovel-ready."

Specht and Harpman are hoping to find an investor willing to pour $300-350,000 into a prototype of their ZeroHouse. As planned, the two-bedroom house would have 650 square feet of indoor space, with an additional 250 square feet of covered decks. The style is a more outer space than back-woods.

A net-zero building generates as much energy as it consumes over the course of a year. It's an idea that's gaining popularity in building circles, and there are publicly funded programs in the United States (via the Department of Energy's Building America Program) and other countries to explore the possibilities.

Builders can approach zero either by generating power on-site with photovoltaic cells or wind turbines, or by reducing the amount of power they need, say by building smaller, "daylighting" with skylights, super-insulating walls, or constructing to take advantage of passive solar heating effects. Most net-zero projects do a little bit of both, trying to balance a moderate amount of on-site power generation with reduced energy requirements.

Specht and Harpman's ZeroHouse is designed to include photovoltaic installation on the roof, four 550-gallon rainwater cisterns, and a sophisticated composting unit underneath the house. To further mitigate its environmental impact, the house is meant to be built on a low-impact foundation of four steel poles. Because it's essentially on stilts the ZeroHouse can even be built over a shallow body of water.

But $300,000 for a 900-square-foot space (including deck space) isn't cheap-that's more than $300 a square foot.

Critics of net-zero building note that some of the most effective means of reducing a building's energy footprint are among the least flashy. Passive solar design can reduce a building's heating and cooling needs by 70 to 90 percent without any pricey photovoltaic cells. Others point out that the energy used to build such a house usually isn't factored into its net-zero standing.

But even if a house doesn't reach net zero, the technology and design innovations that move us in that direction will save a lot of energy in the long run. So critics aside, if Specht and Harpman find their investor we'll have a chance to try out a promising concept that cries out for testing and refinement in the real world.