PHBdW: Passivhaus Bau der Woche 03

foto: Robert Fessler

This week’s PHBdW is a stunning concrete fire station in Wolfurt (AT). The project is Hein Troy Architekten’s winning entry to a limited competition (6 participants) held in 2007. The building is located on the periphery of Wolfurt directly under high-voltage power lines, necessitating a fire-resistant structure. The building incorporates the regional fire department and a Red Cross contingent. We previously featured Hein Troy’s Feuerwehr Schoppernau.

foto: Robert Fessler

This is one of the first concrete structures to achieve the passivhaus standard. While concrete has been derided as an ‘un-sustainable’ material, we’ve run across a number of institutional papers showing that while the resource demand for concrete is greater, the LCA energy of steel is significantly larger, especially with regards to heating and cooling. The fire station achieves a decent score on the science-based Institut für Baubiologie und Bauökologie’s (Institute for Building Biology and Ecology, IBO) Ökoindex-3 (OI3). The Ökoindex is a regional system that grades buildings (wall assemblies, etc) based on global warming potential (GWP), primary energy input (PEI, embodied energy) and Acidification Potential (AP).

foto: Robert Fessler

The apparatus bay has a minimal, low-maintenance concrete finish. Floors, windows and furniture in heated spaces are finished in oak (potentially a nod to the fireman’s axe). The compact form ensures minimal heat loss and keeps envelope costs reasonable – necessary due to additional costs associated with the envelope. The exterior is a textured concrete that changes character throughout the day.

foto: Robert Fessler

Passivhaus standards are achieved via:

  • super-insulated envelope
  • reduction of thermal bridging
  • highly efficient HRV (without subsoil heat exchanger)
  • exterior shading to reduce solar heat gain in summer (outside thermal envelope!)

The building also employs a number of sustainable strategies:

  • Low-VOC materials
  • HFC-free insulation
  • 50m² solar thermal collector providing 75% of DHW
  • A PV array on an adjacent school running the ground source heat pump
  • Optimized daylighting

foto: Robert Fessler

The massing of this project just feels right. The rational form seems very fitting, despite the semi-rural location. The ‘el’ shaped two-storey plan around the apparatus bay also seems highly appropriate and efficient. If this is the new standard for sustainable concrete construction, consider us enthusiasts.

Walls: U-value=0.15 W/m²K (R-38)

Roof: U-value=0.10 W/m²K (R-57)

Slab: U-value=0.13 W/m²K (R-43)

Windows: U-value=0.8 W/m²K (R-7)

Heating Demand: 17 kW/m²/a (5.38kBTU/ft²/a): the Vorarlberg Energie Institut-issued Energieausweis calculated the heating demand at 6.96 kW/m²/a (2.20kBTU/ft²/a)

Further Reading

  • IG Passivhaus entry on the Feuerwehr Wolfurt
  • Vorarlberger Architektur Institut write-up on the building, complete with plans and unmanipulated power lines (PDF, German)
  • Feuerwehr Wolfurt construction and finish photos
  • Guide for calculation of Ökoindex 3 (PDF, German)
  • Sample IBO concrete wall assembly showing OI3 and U-value calculations
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