House Without Heating: Office Building in Austria
Architects: be baumschlager eberle
Location: Millennium Park 20, 6890 Lustenau, Austria
This development has reached a provisional climax in the Lustenau building, a six-storey house that is both massive and monumental in effect, a cube whose white rendered walls and deep-set window openings place it in antithesis to the much lower and flatter industry buildings all around. This is not to imply any inferiority in the quality of these buildings, however; rather, internationally-oriented companies and Vorarlberg architecture have come together in most favourable fashion at Lustenau's Millennium Park, while the subsidiary of the Italian espresso machine manufacturer Saeco on a neighbouring plot is a design by be baumschlager eberle. But all these buildings present themselves in metal, concrete and masses of glass, and thus in the palette of materials typical of modern office and commercial architecture.
An industrial park is undoubtedly a rather unusual site for an architectural office. The architects explain their choice quite pragmatically: the building is located in Vorarlberg – and thus in the home territory of be baumschlager eberle – but if needs be their projects all over the world are within easy reach, whether by the motorway or a plane from Zurich airport. At the same time, the plot at the very south of the Millennium Park offered precisely the planning "tabula rasa" that architects favour when wanting to make a design statement with as little fuss as possible – or so the cliché goes.
The architects shaped the property with white gravel, metal-enclosed pools and newly-planted rows of trees to suit their tastes, thus creating ample space around the white cube without completely isolating it from its surroundings. To introduce variety to the huge monolith, the architects permitted themselves a sole and very subtle device: a slight twisting of the cube against itself above the second and third floors, as if a surgeon had cut into the building and then allowed the edges of the incision to grow together again at a slight displacement.
In the final analysis, showing that this can indeed work without technical equipment is a challenge – a challenge to the fraternity of building services engineers and all those others who in the view of many architects have made building much too complicated in recent years with excessive technology.
Be that as it may, the users of the building are not expected to forego comfortable temperatures, and the somewhat cryptic building name "2226" expresses exactly the temperature range – between 22 and 26 degrees Celsius – that the indoor climate is designed to arrive at by totally natural means. In other words, the new building is basically something that Dietmar Eberle never wanted it to be: a passive house in the original and actual meaning of the word. The necessary temperature stability is ensured first and foremost by an enormous thermal mass: the outer walls consist of 76-centimetre-thick brickwork, divided into an inner, 38-centimetre-thick layer of load-bearing vertical coring bricks and a further 38 centimetres of insulating bricks with a high percentage of core holes. The walls have been given a smooth lime plaster finish on both sides, and the architects hope that with the passing of time the outside plaster will become harder and more dirt-repellent under the action of the sun. The façade may thus be spared the algae growth known to befall thermal insulation composite systems.
The interior walls and even the lift shaft are also made of brickwork, whereas the structural floors consist of pre-cast concrete slabs provided a concrete top course. Battening has been laid on this for a cavity floor, topped in turn by wooden boarding, a layer of footfall sound insulation and anhydrite screed. The latter can be left as is, and makes a virginal impression in areas still to be rented out. This is because cable outlets are not provided a priori; rather, tenants are simply to drill through the floor to the cavity below and lay cables where they are needed. Wood-covered cable ducts are provided along the inner walls as a central hub system.
Naturally "2226" is not really a passive house, even if the outer walls with their U value of approx. 0.14 W/m²K could well meet this standard. Yet although the triple-glazed windows with their completely insulated frames (assuming that 78 centimetres of brickwork can be regarded as insulation) are also a proven element in the passive house construction kit, the office building in Lustenau has no heat recovery ventilation system. Instead the architects opted for window-based or rather shuttered aeration in the form of vent shutters in the façade. These are operated by either mechanical or software-controlled means to ensure a sufficient supply of fresh air both independently of the users on the one hand, and to prevent the building from cooling out in winter or overheating in summer on the other.
Sensors automatically open the vents whenever the carbon dioxide content of the indoor air exceeds a certain level, and on summer nights the building is also "bathed" in fresh air for a cooling effect, whereby the large high-ceilinged rooms (4.21 metres on the ground floor and 3.36 metres in the upper storeys) support the circulation of air throughout the building. The users can override the automatic control system whenever desired to open the vents themselves, but closing takes place automatically. As Willem Bruijn, Managing Partner at be baumschlager eberle, explains, the house without heating indeed reacts sensitively to oversights.
What with high-ceilinged rooms and brick walls 76 centimetres thick, "2226" uses the attributes that many people value in housing typical of the late 19th century. Yet as proved by the window control system alone, the building naturally does not simply return to 120 years ago on a structural design level. Nor does the edifice manage without the 20th-century achievements of construction chemicals in building materials. The flat roof has a classical superstructure made up of sealing foil, 30 to 40 centimetres of Styrofoam tapered insulation and a gravel layer, and the shutter vents in the facade have vacuum insulation panels on the inside and thus the most efficient system that the insulation branch currently has to offer.
"2226" is a simple building – and like so many other simple buildings is the result of a thought and planning process that was all the more complex and multifaceted. The architects soon realised that the calculation standards that form the base of performance certificates would not be of much help since they do not adequately model either the building's enormous thermal storage mass or the true heat loss caused by the automatic aeration system. Rather, the architects relied on their experience first and foremost in their design – and on dynamic simulation calculations done for them by experts from the U.S.A.
In the final analysis, the success of be baumschlager eberle's experiment will depend on two factors in particular: the comfort conditions in the building and its energy consumption, which is measured constantly along with interior temperature, humidity and the carbon dioxide levels in the rooms. At the end of the first twelve-month measuring period, all such results are to be made available to the public.
The building came through its first multi-week heating phase after commissioning in the summer of 2013 without any major hitches. The same also applies to the company's Christmas break of over two weeks. This is quite remarkable, since although the building's interior heat loads are a lot smaller than usual during holidays, the temperature in the rooms remained surprisingly stable. This even held true in the uppermost and still completely empty storey, where the temperature was at about 19.7 degrees Celsius at the time of our visit.
The experiment is also quite remarkable in another respect: while be baumschlager eberle financed the building, they do not use it alone. At present their office occupies only two storeys; a third is let to three planning offices with whom the architects frequently collaborate and a restaurant and the branch of an art gallery based in Munich and Zurich occupy the ground floor. And although you can recommend your employees to put on a warm pullover should the temperature control system fail at some point, such a high-handed approach cannot be expected to meet with the understanding of tenants. To a certain extent "2226" is thus doomed to succeed.
Shortly after its completion, the new building by be baumschlager eberle had become a much-visited object of identification for architects and many other construction professionals.
In a day and age caged in by regulations and constraints, a day and age with a longing for the luxury of simplicity and a growing appreciation of immaterial values, it seems to touch a nerve. The luxury of "2226" can be seen in its generous interior spaces, its use of high-quality materials and the awareness of working in a building designed for a lifespan of 200 years. Luxury can also be seen in the 76-centimetre-thick outer walls, which would undoubtedly be out of the question for downtown investment projects in which every rentable square centimetre counts. Yet "2226" wasn't expensive to build: Willem Bruijn puts the construction costs according ÖNORM 1801, not including fixtures and furnishings and the costs of the property, at Euro 950/m² net. In other words, the architects offset the costs of the enormous room heights, the additional thermal mass and the longevity compared to an average building by dispensing with technical equipment.