A House for Every Season

Formidable, fortified, and immovable with large windows facing southwest. This is how people built their homes more than 800 years ago in Horstmar, in Germany’s Münsterland region, back in the days when noble families resided in the town’s castle and surrounded it with some eight retainer farms for protection. The castle was destroyed long ago, and only four of the farms have been preserved. But recently, at the heart of the oldest one, Borchorster Hof, a new chapter in Horstmar’s residential history began.

On a plot of land on the edge of the historic town center with its robust brick buildings, within only two days, a light, airy house was screwed and welded together from just four sections. Besides boasting the benefits of modular and energy-saving homes, this one can turn to face the sun.

Margarete and Hermann Krafeld’s two sons called their parents crazy when they heard their sudden enthusiasm for this unusual construction concept. But the elder Krafelds thought the invention was brilliant. Developed by Ernst Osswald, a Swabian building contractor from Zoltingen in southwestern Germany, this pivoting house consists of a steel circle mounted almost at ground level, into which 960 30-millimeter (1.2-inch) balls, each smaller than a golf ball, are set at a somewhat lower level. This ball-bearing device is driven by a 1.5-horsepower motor that consumes just 200 German marks [US$90] of electricity a year. Together, they form the heart of a house that never has to stand in the shade.

To make room for it, Hermann Krafeld, the owner of a local wedding and evening-wear store, cleared the piece of land he had inherited from his father. On the first day of construction, more action was going on in the Krafelds’ street alone than in the entire town of 6,715 inhabitants. At sunrise, two trucks squeezed their way into the narrow street after having traveled overnight to deliver the four house sections. The two halves of the ground floor and two halves of the upper floor were rendered white on the outside, wallpapered, and equipped with lamps, power sockets, and kitchen tiles—almost like building blocks for an oversized dollhouse, except this one has 188 square meters (225 square yards) of living space.

At first, the construction site looked something like a playground. A kindergarten class even took advantage of the spring morning for an outing to watch in awe as the crane lifted the first half of the ground floor, heaved it over a hedge, and with a swing, slowly placed it onto the steel circle, half of which then disappeared. The motor that drives the revolving device is situated beneath the house, making it resemble a model rather than a modular home. While the builders were still busy working on the steel girders for the terrace, which of course will revolve with the house, someone started up the motor, and the building began to turn even before the roof was in place.

Until a few years ago, Osswald, a site engineer and master bricklayer by trade, worked on conventional German houses. One day while watching his children at play, he saw them place a plank on some marbles so that it could revolve. That should be possible with a house, he thought to himself, realizing that such a construction could save a lot of energy.

Itching to see if his idea would work, Osswald finally got together with an acquaintance and developed and patented his captivatingly simple concept. Although there are other revolving houses in Germany, they are either suitable only for wood-frame homes or are substantially more expensive. Above all, they usually tower in the air on top of a support, or the support has to be sunk into the ground, which makes it impossible, or at least difficult, to build a basement. In contrast, Osswald’s ball-bearing frame is almost at ground level, making it easy to add a basement.

By the next evening, the house was ready. Inside, the noiseless revolving mechanism can be operated by a switch, forward and backward, slow and fast. But this is no carousel: A complete rotation requires 60 minutes. Most owners of such houses set them to rotate slowly at a prespecified rate to follow the course of the sun, thus taking full advantage of its rays. This floods the house with light and enables the sun’s warmth to be stored via the parquet floor and walls.

The Krafelds hope to reduce their energy consumption by 40 percent by means of the torque alone. Another 60 percent will be gained from the use of solar cells and insulation, employed by Germany’s 1,000 or so self-heating houses. A Reimlingen family living in an Osswald house has reduced its energy costs to 500 marks [$225] a year. According to Osswald’s calculations, the ball-bearing frame, which costs 18,000 marks [$8,130], pays for itself in eight years. The entire house costs less than 400,000 marks [$180,652].

For the Krafelds, who lived in an apartment over their store, it was not only easy to move into this house with its enormous kitchen and a guaranteed place in the sun. It was also the start of a new life. Since vacationing on Crete two years ago, Mrs. Krafeld has suffered the aftereffects of Legionnaires’ disease. Krafeld visited his wife in a clinic every day and strolled with her in a wheelchair to sit in the sun, noticing that she would immediately brighten up. After realizing that the sun was good for her, he began looking for an appropriate house. And now they have it.