When St. Helena architect David Hanawalt told Habitat for Humanity he could design 10 of the most energy-efficient family homes ever constructed in Michigan, he didn’t know they would be tested during one of the state’s most severe cold spells. No matter. After one year, one of the families ended up with a utility bill of less than zero, while the other two had bills of $50. Today, after a few modifications, the houses produce more energy than they use.
Source: Napa Valley Register