What's being called the world's first "active" zero-carbon house uses solar panels to generate more energy than it uses, devoting some of it to warm an under-floor heating system, Britain's newspaper, The Guardian reports.
The house, in the Danish town of Lystrup, uses 538 square feet of solar panels to generate electricity and is computer-controlled to regulate the internal temperature. When the electricity generated by the solar cells isn't sufficient, a back-up electric pump keeps floors warm. However, the house is said to generate extra electricity eight months of the year, which it sells back to the grid.
The house is called "active" to differentiate it from "passive" eco-houses that use zero or little net energy. To cut heat loss, passive designs tend to have few windows and those only on the south side. They have heavy insulation and instead of a heating system, use a heat exchanger to warm fresh air entering the house. In contrast, the "active" house has large expanses of windows, equivalent to 40% of total floor space, The Guardian states. No surprise, a window manufacturer commissioned the design.