PHBdW: Passivhaus Bau der Woche 06

foto: Bruno Klomfar

The Austrian firm of Dietrich|Untertrifaller has completed some of the most incredible projects in Vorarlberg, including a fire station in Mellau. This project was one of the first passivhaus schools completed and is an excellent demonstration of a school that succeeds on architectural, ecological and energy fronts. We wish all LEED Schools performed this well and looked this amazing – especially for the same cost. It would certainly be harder for organizations to highlight the failures of LEED certified schools (or other LEED buildings) if they were nearly as efficient as passivhaus projects.

foto: Bruno Klomfar

Hauptschule Klaus is a compact addition to a 1970s school and sports hall for the villages of Klaus, Weiler and Fraxern. Above-grade construction for the two-level building (with basement) is timber, except for the concrete stair cores. A central atrium features operable skylights that are used for illumination, ventilation and smoke abatement. The operable skylights also assist with night cooling during summer. The openness of this space allows for a really incredible effect. The stones at the ground floor aren’t purely decorative, they add thermal mass to the atrium.

foto: Bruno Klomfar

The south elevation features a perforated copper sunscreen, and operable sun shades on the east and west facades control glare and solar heat gain into classrooms and the library. These screens are all positioned outside the thermal envelope. The lower windows allow unimpeded views for sitting students – having attended a number of schools that had few windows – this must surely be a treat.

foto: Bruno Klomfar

Heating is supplied via the ventilation system, a Bösch rotary HRV.  26m long earth tubes are used to pre-condition incoming ventilation. Additional sustainable strategies include roof-mounted photovoltaics, a green roof, adequate daylighting and extensive use of regional materials.

foto: Bruno Klomfar

Wall assembly, U-value=0.11 W/m²k (R-51)

  • 15mm birch plywood
  • 50mm battens w/ rock wool
  • vapor barrier
  • 27mm kerto (engineered lumber by finnforest)
  • 180 mm insulation
  • 27mm kerto
  • 120mm battens
  • air barrier
  • 40mm battens
  • 24mm silver fir rear ventilated rainscreen

Roof assembly, U-value=0.11 W/m²k (R-51)

  • 22mm OSB
  • 380-520mm framing w/ insulation
  • 30mm OSB
  • vapor barrier
  • 300mm rock wool
  • 3-ply modified bitumen
  • green roof
  • Floor/cellar: U-value=0.18 W/m²K (R-31.6)
  • Windows: U-value=0.76 W/m²K (R-7.3), center of glass U-value=0.6W/m²K (R-9.5),
  • Airtightness: 0.5 ACH50
  • Heating Demand: 14.3W/m²Ka  calculated w/ PHPP (4.53kBTU/ft²/a),  11.4W/m²Ka  measured ( 3.61kBTU/ft²/a),

This school was able to achieve a 70% reduction in energy costs compared to the existing school – with only a 3% increase in construction costs. Needless to say, we’re enamored with this project. What would it take for U.S. schools to adopt a similar model? Passivhaus is a proven strategy towards low-energy buildings, and with the  integration of photovoltaics  an option for energy-producing, CO2 neutral schools. Furthermore, this school is yet another public building derived from an architectural competition. Unbelievable.

  • Architect: Dietrich|Untertrifaller, Bregenz (AT)
  • Structural (wood): merz kley partner, Dornbirn (AT)
  • Mechanical: Synergy Consulting and Engineering GmbH, Dornbirn (AT)
  • Location: Klaus (AT)
  • GFA: 4,522 m² (48,675 ft²)
  • building costs: 1,614€/m² ($169/ft²)
  • completed: 2003

foto: flickr user janorama

Further Reading

  • Photos
  • More photos of the school
  • Plans, section and additional photos in a brochure by Synergy GmbH (pdf, German)

2 responses to “PHBdW: Passivhaus Bau der Woche 06

  1. namhenderson

    I like this These screens are all positioned outside the thermal envelope. .

  2. nam,
    exterior screens are one of the best strategies for avoiding excessive solar heat gain (and overheating) with a passivhaus project.

    plus, they can be really phenomenal, like the second passivhaus in france.