Passive house 'plus' - Open House in Hamburg

'Open House' is an IBA project  involving construction of a residential building with 22 apartments (owner occupied or rented) as well as a common room, offering approximately 3,750 m² of living space in total. In this building, three investors – Steg Hamburg mbH, Schanze eG and Baugemeinschaft Schipperort – have realised three different forms of housing for a mixed group of residents. The west and east wings contain 32 state-subsidised apartments for rent , while the south wing is made up of seven privately financed city houses, as well as four loft apartments and a maisonette.

The new construction is the result of an expert assessment and free space planning workshop procedure conducted with 4 participants in 2007. The favoured design, by Onix Architekten from Groningen, proposed a three-wing, four-storey solid construction with each wing financed by one of the investors. The technical facilities room, common room, storage rooms and drying room are located at the wing interfaces.

'To live with each other instead of next to each other' was the primary objective of the cooperation partners and the future residents of the complex. The latter – owners and tenants – were involved in the planning of the project right from the start, in an effort to meet the individual requirements as closely as possible. The neighbourly cooperation concept characterising the Open House continues inside the residential units, which are open for the individual needs and ideas of the future owners.

Passive house 'plus' means: Less primary energy
Appropriate energetic measures are intended to significantly reduce the primary energy demand compared to a standard passive house, with corresponding savings in CO2 emissions. The following energy systems are planned:

• two micro combined heat and power (micro-CHP) systems with 12.5 kWth and 5.5 kWel respectively, first base load with 100% biogas operation, second base load with natural gas operation, peak load operation with natural gas condensing unit with at least 80 kWth and a guaranteed biogas supply of min. 40% in total
• Photovoltaic system (99 kWp): A photovoltaic system operated by the Genossenschaft Bürger-Solarkraftwerke Rosengarten is installed on the roof areas of the three building wings.

Energy design calculations predict that approximately 800 full load hours per year can be expected for the system. The generated electricity is remunerated pursuant to the Renewable Energy Sources Act (EEG) and fed into the public power grid. The primary energy demand is reduced to 33 kWh/m²a instead of 120 kWh/m²a (Passive house-plus/Passive house-standard comparison, including domestic current) according to expert assessment. Energy consumption is to be monitored over a period of two years after completion of the building and once the residents have moved in.

Urban development plus points
The Open House built on formerly unused land closes a gap in the urban planning landscape and forms a border to the Ernst August Canal. As opposed to many of the other proposals submitted to the expert assessment procedure, which planned a perimeter block development, this design neither blocks the view of the canal, nor access to it.
 
Support by IBA Hamburg and BSU
The Open House turned out to be more expensive than a standard passive house, due to the special architectural concept and the high demands on energy efficiency. The additional costs are borne by funds for climate-related matters from the Behörde für Stadtentwicklung and by the IBA.
 
Data and facts:
Project partners: WBG Schanze eG, represented by STATTBAU Hamburg; steg (Stadterneuerungs- und Stadtentwicklungsgesellschaft) Hamburg mbH [Urban Renewal and Development Company];
Baugemeinschaft 'Schipperort' GbR [Joint Building Venture] , Bürger-Solarkraftwerke Rosengarten eG, Hamburg [Citizen Solar Power Stations Cooperative] ; Agentur für Baugemeinschaften [Joint Building Venture Agency]; Behörde für Stadtentwicklung und Umwelt [Urban Development and Environment Authority]; Bezirksamt Hamburg-Mitte [District Office of Hamburg-Mitte]

Architects
Competition prize winner: Onix, Groningen
Design and planning: ARGE ONIX/Kunst+Herbert, Hamburg
Landscape planning: arbos Landschaftsarchitekten, Hamburg
Energy design: Schiller engineering, Hamburg
 
Project data
Project costs: 9.8 million € in total
(cost groups 300 and 400 (building constructions and technical installations): 6.4 million €)
Plot size: 5,812 m²
GFA: 4,600 m²
 
Prices
Rent: 5.50 to 6.80 €/m² net excl. utilities
Purchase price of city houses: 2,300 to 2,700 €/m²