Since we’re going over planning of multi-family projects in the Certified Passive House Consultant training, we decided to take a close look at a passivhaus project recently completed in Freiburg. The complex, two compact apartments, stands out amongst the rest of the buildings that make up Vauban.
The Kleehäuser (as the units are located on Paul Klee Strasse) by Common + Gies Architekten were developed by 24 parties banding together to build 25 units (10 condos, 14 apartments and a guest apartment). This project builds upon a passivhaus apartment building Common + Gies completed in 1999. The floor plan is a simple module, designed so iterations and adjustments by owners could be easily accommodated. The building is designed for accessibility and is a true intergenerational house, with residents ranging from a few months to nearly 80.
Exterior and interior bearing walls appear to be made from kalksandstein, a product similar to CMU. To achieve passivhaus, a few inches of rigid insulation would be added outside of the kalsandstein, though we weren’t able to verify this. The three story building is finished with a wood ventilated rainscreen, larch would be the first guess. The five story building is finished with a ventilated corten rainscreen. Both materials have started to weather and looked great when we visited last spring.
The initial project costs were about 10% over standard construction costs, and payback is expected to be less than 10 years. This appears to be a bit on the high end of passivhaus costs. Construction took about 13 months.
The building also employs a number of sustainable strategies:
- Southern Orientation, with balconies that are routinely utilized.
- The green roof is also a nice touch, considering the district.
- Renewables that remove 10% more than the building’s CO2 usage, include a 7 kW photovoltaic array and community ownership in local wind energy.
We were also really impressed with the perforated metal enclosures for bikes and waste/recycling bins. The detailing is pretty amazing and far exceeds most of the local bike garages.
Walls: U-value=0.17 W/m²K (R-33.5)
Roof: U-value=0.11 W/m²K (R-51)
Windows: U-value=0.98 W/m²K (R-6)
Heating Demand: 15 kW/m²/a (4.75kBTU/ft²/a)
PrimaryEnergy Demand: 37 kW/m²/a (11.71kBTU/ft²/a)
- Architect: Common & Gies Architeken, Freiburg (DE)
- Engineer: Ingenieurbüro Feth
- Mechanical: solares bauen GmbH
- Location: Vauban, Freiburg (DE)
- GFA: 2,540 m² (27,340 ft²)
- completed: 2006
- building costs: 2,171€/m² ($258/ft²)
- awards: 2008 BDA Auszeichnung Guter Bauten
- More photos and info on the Kleehäuser website
- If you happen to be staying in Vauban, you can try out living in a PH apartment
- City of Freiburg write up on energy efficient housing (PDF, German)