Open House in Hamburg by Onix Architekten
This Passivhaus for communal living produces more energy than it uses.
Architect Onix Architekten
Completed February 2012
As part of IBA Hamburg 2013, the international sustainable building exhibition inaugurated in 2007, Onix Architekten has designed the Open House, a Passivhaus for communal living that produces more energy than it uses.
Situated on the island of Wilhelmsburg, the €10 million project was originally going to be three separate buildings — funded by three different investors. Onix brought them together to create a three-winged, Y-shaped building, centralising services and reducing the facade area to create a mixed-tenure scheme.
The east and west wings contain 32 state-subsidised apartments for rent, while the southern wing is made up of seven privately funded townhouses, as well as four loft apartments and a maisonette.
“To live with each other instead of next to each other” was the primary objective of the project, in-keeping with Hamburg’s long tradition of cooperative housing. Future residents were involved from the beginning, developing ideas for communal spaces, and will finish building the townhouses themselves.
The project is constructed with blockwork walls, with 300mm insulation finished in Sto render, while all windows are triple-glazed. Pebbledash is used in areas that will receive particular wear — the original choice of timber cladding was abandoned, as screws would have formed a thermal bridge, reducing the Passivhaus credentials.
The building employs sustainable energy systems that reduce its emissions beyond the passive house standard, including:
- Two micro-CHP systems, of 12.5kWth and 5.5kWel respectively. The first is 100% biogas, supplemented by a peak-load boiler with an 80kWth natural gas condensing unit, guaranteeing a minimum biogas supply of 40%. The permissible CO2 emission of 64 tonnes, defined in the Hamburg Climate Protection Regulations, can be reduced to a maximum of 10 tonnes in a year. Under optimum conditions, with a high production of green electricity, the calculated CO2 emission could even amount to below zero.
- A photovoltaic system (pictured above) of 99kWp is installed on the roof, operated by the citizens’ cooperative solar power company, Rosengarten eG. Excess generated electricity is fed into the local power grid, making it possible to save around 29 tonnes of CO2 annually. Energy design calculations predict that approximately 800 full load hours per year can be expected from the system, with primary energy demand reduced to 33kWh/m², compared to the passive house standard of 120kWh/m².
Design architect: Onix, Groningen
Executive architect: Kunst & Herbert, Hamburg
Landscape planning: Arbos Landschaftsarchitekten, Hamburg
Energy design: Schiller Engineering, Hamburg