Passive homes are built to use as little energy as possible, but the future of green housing might be active homes -- houses designed to capture more energy than they use.
The world's first active house, located in Lystrup, Denmark, contains 50 square meters of solar cells and solar panels to warm underfloor heating. The whole system is controlled by a computer that monitors the temperature and opens, closes, and adjusts windows. Even with two flat screen TVs and a washing machine, the house produces more energy than it needs. Unlike passive houses, which open toward the south, the active house is covered in windows to let in light. Engineers calculate that the home will have produced enough power in 30 years to cancel out the $794,400 cost of building it.
In comparison, passive houses rely on effective insulation, heat exchangers, and overall energy conservation. They don't usually produce excess energy, but they also use very little. Don't be surprised if they are ultimately usurped by active houses--most of us want to do right by the environment but also keep our creature comforts.
[Via UK Guardian]