In the Austrian city of Ernstbrunn, Juri Troy Architects has completed a suitably sustainable extension to the headquarters of the renewable energy company Windkraft Simonsfeld. The U-shaped volume spans two storeys and connects to the original building, designed by architecture firm Reinberg, to create a central atrium. The new wing houses offices alongside a reception area and spaces for catering and events.
Constructed from local timber, rammed earth and eco-concrete, the extension integrates geothermal heating and cooling, passive climate control and renewable energy systems, which together enable the building to operate with a positive carbon footprint. It has achieved the highest rating of 1000 out of 1000 points under Austria’s Klimaaktiv Gold Standard, a benchmark for sustainable construction.
Flexible floor plans and a design that combines old and new
To reduce dependence on artificial lighting and mechanical ventilation, the new building's design maximizes daylight and air circulation. The ground floor of the building houses a new reception area, a cafeteria, and a flexible space for events and meetings, while the upper floor accommodates new office space. Built around a green central atrium and featuring large windows, the headquarters opens up to the outside, creating visual connections and a link between the old and new buildings.
Designed with local materials for CO2-positive performance
The materials for the building were sourced locally. The timber frame and exterior walls are made of spruce and silver fir from STROBL Bau, while the interior walls are made of rammed earth from a nearby clay pit supplied by Pro Lehm. Terrazzo floors, made by Schüller Bau from locally sourced materials, complete the interior surfaces and underscore the building's environmentally friendly and biophilic material palette.
The building's energy efficiency is enhanced by thirteen deep boreholes that supply a geothermal system with a heat pump for low-carbon heating and cooling. The façade is equipped with sunshades on the sun-exposed surfaces, and the roof is fitted with photovoltaic modules that generate renewable energy on site. These elements ensure exceptional energy efficiency: the headquarters has a heating requirement of 28.5 kWh/m² per year, a primary energy requirement of 38.9 kWh/m², and CO₂ emissions of 5.4 kg/m².
Plant-based art continues the connection to mission and location
Inside, the interior design is complemented by commissioned work from the CARAVANATELIER design studio. ZWISCHEN HIMMEL UND ERDE uses natural plant dyes on organic fabrics to reflect the company's connection to the environment. The Earth Room is fitted with panels dyed in red and earth tones that reflect the world beneath our feet and at eye level, while the panels in the Sky Room feature blue tones reminiscent of the changing intensities of the world above us. All panels have the same surface pattern, but their unique arrangement creates different textures and emotional experiences that connect the interior of the building—and the work performed within it—to the outside world.
