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The Heliotrope House Automatically Follows The Sun Like A Plant

The sun is the greatest source of energy on the planet. Instead of spending money trying to fight its power in the summer (and supplement it in the winter), revolving homes maximize solar heat and electricity.

If the siting of a home in relation to the sun is so important--think of everything you've ever heard about south-facing windows--why can't buildings simply rotate to take advantage of natural light? It may sound like a lot of effort just to achieve pleasing aesthetics, but when you're using the sun as your primary source of heat and electricity, which is true in some advanced sustainable building techniques, it starts to make sense.

Structures that turn on an axis to follow the sun aren't new. One of the most famous examples is George Bernard Shaw's writing shed, which sat on something like a big lazy susan and could be pushed to achieve the best light and view. In the early 20th century, before the warming effect of the light coming through the windows of a home was replaced by more convenient sources of heat, rotating sheds were not uncommon in English gardens.

Despite--or perhaps because of--the simplicity of this idea, it's persisted all the way to the present, when rotating buildings have become some of the most advanced structures on the planet, from an energy efficiency perspective. Architect Rolf Disch's Heliotrope House, which was the first "energy positive" house in Germany to pump more power into the grid than it drew, is perhaps the most famous example of this technology.

Disch's house borrows its name from heliptropism, a phenomenon common to plants that live in the Arctic, where the growing season is short. During a never-ending summer day, Arctic poppies will follow the sun around and around, using its rays to warm their petals so as to attract insects.

By turning on its axis, the Heliotrope House can aim its solar panels so that they achieve maximum power production. But it also accomplishes a number of things that might not be as obvious. The first is passive solar heating. When constructing a home that uses nothing but the sun for heat--the so-called Passive House standard--the siting of the house in relation to the sun becomes extraordinarily important. A home that can actually track the sun is so efficient at capturing the heat energy of absorbed light that it's actually in danger of overheating in all but the coldest conditions.

That's the second intriguing thing about a home that turns with the sun: It can copy a second, related ability of plants, known as paraheliotropism. Paraheliotropism is the tendency of some plants and leaves to avoid sunlight that is too direct. Because the Helioptrope hHouse is glass on one half and super-insulated wood on the other, it can turn its opaque side to the sun during the summer in order to shade the rest of the house. As a result, a heliotropic house is unusually flexible in the face of a range of conditions, making it potentially better suited to the higher variability in weather patterns that comes with our changing climate.

There are dozens of examples of other buildings that follow the sun. The 1935 Villa Girasole home sweeps its 1,500 ton bulk across its grounds at the rate of four millimeters per second, driven by a three-horsepower diesel engine. In 1958, a Belgian coal merchant built his wife a revolving home with, oddly enough, a concrete roof that remained stationary. More recent examples of rotating homes have been constructed in Australia, and Germany, and anyone seeking a builder for homes in this style can commission Solaleya, whose dome homes feature interiors that are nothing short of stunning. At least two spinning condo complexes have been proposed for Dubai.

What all of these buildings have in common is that rather than fighting the sun through conventional air conditioning and heating, they can use it to achieve a comfortable interior temperature simply by changing their relationship to it. It's a step beyond the passive building standard that is impractical for most construction, but at least points the way to systems that are so in tune with nature that they can shed many of the dependencies we assume all buildings must have--namely, access to external sources of energy.