Haus R[ömerstrasse]-128

Werner Sobek is the director for the Institut für Leichtbau Entwerfen und Konstruieren | Institute for Lightweight Structures and Conceptual Design (ILEK), as well as the MvDR visiting professor at IIT. His own office is quite productive, performing engineering services, design services and green consulting for numerous firms around the world. Sobek’s green services include passivhaus consulting, although Sobek has said regarding passivhaus, “you live like you are in a Styrofoam box” – a nod to the thick, super insulated walls typically needed to meet the rigorous standard. Haus-R128 is Sobek’s own experimental residence, which is somewhat of a theme for Baden-Württemberg.

While this house is not new, recent journal publications have us revisiting this knock out. It’s definitely one of our favorites.

And lately, Sobek’s been pushing what he’s calling Triple Zero®:

Zero Energy Building

The building requires no (ZERO) energy. The energy generated from regenerative sources on and in the building or the immediate piece of property upon which the building stands is at least equal to the entire primary energy requirements of the building for heating, cooling, hot water, auxiliary power and power for all typical domestic applications.

Zero Emission Building

The building produces no (ZERO) CO2 emissions. The reference value is the total primary energy demand, which is then converted
to CO2 emissions. No burning processes are permitted in the building or on the property.

Zero Waste Building
No waste (ZERO) is produced when the building is being converted or deconstructed. At the end of their life cycle all building
elements can be fully recycled without any components needing to be burnt or sent to a disposal site. The plot of land can be returned
to nature without any fear of contamination or residual waste.

Haus R-128 is a direct execution of Sobek’s Manifesto. This 4-story glass hut is situated on a steep, northwest facing slope with unimpeded vistas over Stuttgart. The area is abundant with vegetation and is considered a ‘green lung’ for the city. The plan, like the building, is almost completetly open. From the street, the house is reached by pedestrian bridge to the top level. A technikbruecke or service bridge, carries cables, waste lines and water. As one descends, each level becomes increasingly private. Once inside, there are no partitions or built-in furniture. The structure, a steel grid built on a concrete pad, was erected over the footprint of a previous building. The only closed-off spaces within the house are stacked bathrooms. The technical aspects of the house are daunting: there are no door levers or switches and everything is voice or sensor activated – a level of high-tech that we really can’t fathom. This kind of asceticism puts John Pawson to shame. It’s really hard to appreciate the subtle curves and weight of a nice FSB lever when it isn’t needed!

Zero Energy Building

Here at Brute_Force we are big proponents of zero energy, though we’ve yet to come close on anything we’ve built. The energy for the house is generated on site with roof-integrated photovoltaics. 48 monocrystalline laminate PV panels are laid flush on the fifth facade (roof) – with a max. capacity of over 6.5 kW/h. Another 24 panels reside on an accessory building.

The windows play a primary role in the zero-energy system. Windows are 2.80m high, 1.36m wide on north/south, 1.42m on west/east – corresponding to the structural grid.  The argon filled triple pane windows have a metal coated foil between 2 panes and achieve a U-value of 0.4. The foil prevents radiation from overheating the house during the intense heat of summer. Since frames aren’t as effective at preventing thermal loss, there are only a handful of operable windows on each level .

In the summer, excess heat is collected in copper piping running along the ceiling of each level and distributed to a (presumably highly insulated) 12,000L storage tank. The tank stores the heat until winter when solar radiation levels are significantly lower. Seasonal storage of solar energy is one of the primary areas of study for the ILEK.

It appears that the house is oriented to take advantage of the evening breezes (flowing along the valley in a northeasterly direction) and the open plan would allow adequate stack ventilation.

Zero Emission Building

As the building is powered solely by PVs, there are no emissions created to power the building. Furthermore, there are no fireplaces. Glues and seals are avoided.

Zero Waste Building

Haus R-128 is a light-framed steel structure conceived around the idea that every part can be disassembled and re-used or recycled. Sobek argues that in a passivhaus (as most other construction), everything is glued/sealed, making recycling of most materials practically impossible. The steel, glass, roof insulation, floors, etc. are not glued down. Everything is bolted, clipped or placed, as avoidance of glues (and thereby VOCs) was a top priority.

The floors are plastic-covered wood panels resting on angles between beams. Aluminum ceiling panels are clipped into place and have voids for lighting, seasonal storage copper pipes for and acoustic inserts.

The entire project was assembled in 11 weeks, including 4 days for the bolted steel structure.


architect/engineer: Werner Sobek

energy consultant: Transsolar

photos: Roland Halbe

completed: 2000

cost: €770,000

awards: 2003 Hugo Häring Preis (BDA),

Further reading:

Stuttgart’s incredible urban climate page (this would be a great resource for any city serious about net-zero or 2030)


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