Upending the stereotypical image of the flat countryside of Flanders, a new low-energy house built by the Belgian design firm AST 77 mixes modernism and organic materials to blend into a steep, forested hillside near Rotselaar, Belgium. With green amenities such as a heat pump, radiant underfloor heating and high-performance insulation, the house is as energy efficient as it is attractive.
The chief exterior materials of the Rotselaar house are bamboo poles, lined up in precise rows at regular intervals along the rectangular 86-foot-long steel-frame box, broken up by a series of square windows positioned for natural ventilation and passive solar warmth. The overall visual effect is reminiscent of a tree trunk rising out of the hilly terrain.
Although the structure may resemble a simple bamboo tree house, it contains thoroughly modern amenities and ample insulation for the cold Belgian winters. While some interior walls are painted in solid colors, the builder reduced the use of paint by leaving some section exposed, showing the locally sourced oriented strand board underneath.
Less than 15 feet in width, the narrow 1,270-square-foot house gives the impression of a much larger envelope with a open floor plan that echoes the adjacent hillside in a series of stepped levels. The diagonal space this creates draws the eye along the long axis and emphasizes the volume of the interior.
The residence was built upon the old foundation of a demolished house on the property. To minimize the disruption of the site, the AST 77 architects incorporated the previous house’s retaining wall that was still imbedded in the hillside. Instead of facing the street, the house follows the contours of the hillside
To cut down on water usage, the house includes a rainwater collection system on the sloping roof that funnels runoff to a basement filtering unit. The water is then recycled for irrigation in the house’s garden. Now that the site is finished, the owner says more trees will be planted on the site to provide additional shade in the summer months.