As homeowners contemplate the horror of winter heating bills, one Falls Church family is hoping that their new custom-built home will save them a small fortune.

Wendy Koch, husband Alex Keenan and their two girls live in “Right-sized Green,” a home designed to provide the maximum possible energy savings in an average-sized home. The design is so innovative that the home was featured as a stop on this year’s DC Solar Tour, a regional showcase for green homes.

The size of the average home has more than doubled since 1950, from 983 square feet to 2,349 square feet in 2004. That average figure does not adequately reflect the recent growth in even larger homes, sometimes dubbed McMansions or Hummer homes. Along with the extra space, most homes now feature a vast array of energy-hungry appliances, from giant refrigerators to computers and home cinema-sized televisions.

Wendy Koch, who writes for USA Today, and her husband used to live in a much larger 5,000 square foot home in McLean when they realized, with some horror, that they had seven sofas and far more space than they needed or could justify. The search began for a way to downsize.

Settling on a quarter-acre plot in North Virginia Avenue, Koch started to investigate options for green energy.

Despite the promise of much-improved solar energy designs and the oft-repeated fact that the sun delivers more energy to the Earth in one hour than the entire human race uses in a whole year, she soon found that green design has to reflect local conditions.

Unfortunately, what Koch found was that, due to the shade provided by the abundant trees she loved, her home would not receive enough sunlight to justify solar installations to generate electricity or heat water. There wasn’t enough wind to drive a small turbine. Nor was geothermal heating a great choice as the drilling would have to be vertical and extremely expensive.

Koch and Keenan settled on a radical alternative: Passive solar or solar orientation. They had their whole home designed to align with the sun, absorb as much energy as possible and, through extremely efficient insulation, retain it. The design used recycled materials where possible, recycles rainwater, employs a super-efficient hybrid gas and electric heating system and seeks to minimize environmental impact, right down to replacing lawn areas with attractive but drought-resistant plants.

Koch said that her motivation was to dramatically reduce their carbon footprint and increase the sustainability of their lifestyle. The new home does not include a garage, but makes excellent use of all available space, including the conversion of the basement into an in-law/guest suite. Koch said that, while she was aware of some of the extremely adventurous alternatives to large home living, such as the playhouse-sized 100-250 square foot houses offered by Jay Shafer of Tumbleweed Tiny House Company, it would not have been a good option.

a good option.

“My daughters would have killed me,” she joked.

The custom design and build option is not for everyone. Construction costs were about $175 per square foot.

“If you are planning to go that route, you should get the best possible advice to plan your budget, and then double it,” Koch joked. “You also need to think about what level of stress you can handle. It can be very rewarding to build a custom home, but it can also be very stressful, time-consuming and expensive.”

Asked what advice she would give prospective green home owners, Koch said, “You do not need to build a new home and design everything from scratch to radically lower your carbon footprint. There are increasing numbers of builders offering established green home packages, but, for most homeowners, the greenest thing you can do is to insulate your home thoroughly, visit the Energy Star website and replace old and failing appliances with Energy Star-rated efficient appliances, only have them on when you are using them, and make the best possible use of the space you have.”

To help others find their way to greener living, Koch writes a blog detailing her family’s experiences that also covers news from the wider movement toward a more sustainable lifestyle.

For Koch, sustainability is about more than minimizing our impact on the environment: “It is also an economic issue,” she said. “If we spend less time working to support our lifestyle, we can enjoy life a little more.”

“Right-sized Green” is now being considered for a LEED (Leadership in Energy and Environmental Design) Platinum certification, the highest national benchmark, from the U.S. Green Building Council, and, although it is too early to compare utility bills, Koch said, hopefully, “We haven’t turned on the heat yet. Even when we’ve had several consecutive days in the low 50s, our house has stayed at 69 degrees or higher.”

For more information on Wendy Koch and her project, visit USATODAY.com/communities/greenhouse.