1960s run-down housing estate

The Ellebo housing estate located 15 kilometers Northwest of Copenhagen is typical of the 1960s urban developments, with buildings surrounded by grounds featuring playgrounds, playing fields and green recreational areas.

The 4 buildings, defining the contour of an incomplete perimeter block, are characterized by building damage typical of buildings of that time: damage to built-up roofs, windows, installations, etc. Additional insulation was installed in 1992, but the estate is currently run-down and in great need of renovation.

One purpose of the renovation is to ensure a good indoor climate in housing units while at the same time minimizing energy consumption; another is to make the estate adaptable to future needs and demands, which include additional building facilities for a total of 5.000m2, improved accessibility for people with mobility disabilities, combination of flats to achieve larger units, as well as improving the overall architectural appearance of the buildings.

While the 200 on-site parking spaces located in the perimeter of the estate and on the grounds are to be retained, the client also requests additional parking space along with an improvement of the outdoor areas, which are to be used more actively to generate social interaction.


The Spiral creates a movement, a common flow uniting different entities into one whole.

In nature, it provides a unifying structured beauty.

We propose a SPIRAL of GARDENS to support the transformation of the Ellebo housing area into a modern sustainable urban environment which merges urban living and nature into a new whole.

The SPIRAL of GARDENS provides a new identity, and structures a walkable neighborhood with increased health benefits, opportunities for increased social interaction and reduced carbon emissions.

It adds to the existing building hardware structure new typologies, productive public space and personalized interfaces of individualized residential units, gathered into a vital community by a unifying landscape of private gardens and public green.

4 Context-specific issues&potentials

A number of 4 different context-specific issues and potentials to be addressed have been identified: accessibility, segregation, borders and uniformity.

1.-Accessibility: Ellebo housing estate has good access to infrastructure and public transportation, recreational and shopping facilities. The good accessibility conditions make it highly attractive for further development as a residential area; however improved accessibility is needed.

+Typologies and better access: We propose to add a variety of housing typologies and new programs to the existing structure, along with improving access conditions, in order to reinforce the housing estate as a vibrant residential area.

2.-Segregation: The housing estate is situated in an area characterized by functional segregation: in spite of the good traffic and road conditions, there is no exchange between the different functional areas.

+ Public green: We propose to add an intense layer of green public space to make the development friendlier to people living, visiting, enjoying or spending time in the area.

3.-Borders: The current division between the inside and outside contributes to creating a closed an unfriendly environment.

+ Open facades&corners: We propose to transform corners into green gates with elevated plazas and open up the facades to create an inviting border: a personalized inter-face of front gardens, balconies and winter gardens.

4.-Uniformity: The monolithic and uniform appearance of the housing blocks lacks human scale, identity and differentiation.

+Diversity: We propose to add program and different scales to create possibilities for differentiation which ’humanize’ the blocks. We target both customized individualization and a richer public realm to support the creation of a new community identity.

3-fold retrofit strategy

A three-fold retrofit strategy for ground floor, buildings and roof areas has been developed to make the most of the context qualities and opportunities.


The Spiral rooftop is the productive layer of the retrofitting strategy.

+ENERGY: Recyclable solar cells are mounted on all South-West oriented (sloping) roof surfaces.

+FOOD: Gardens and glasshouses enable on site food production.

+WATER: Rainwater harvesting provides water for the food production. The surplus of rainwater is directed towards the corner roof plazas, and from there down to rain gardens.


Renovation of existing buildings minimizes energy use and heightens living qualities.

OPTIMIZE DAYLIGHT: Open up and ’wrinkle’ the South and West facades to maximize daylight.

INSTALLATIONS: Lightweight prefab kitchen/bathroom units secure water saving, natural ventilation and flexible open living/eating.

SAVE: New insulation minimizes the energy required to heat and cool the building, providing a better indoor environment.

NATURAL VENTILATION: Operable windows and shafts/skylights secure natural air flow.

RECYCLABLE MATERIALS: The prefab kitchen/bathroom units are eco-friendly. Wooden cladding panels absorb Co2 and can be reused at end life.

ADD: The requested 5.000m2 extra program is divided between penthouse additions on the East/West oriented roofs and a new addition containing duplex & atelier apartments ‘inside’ the perimeter of the existing housing estate. The new building ‘steps down’ to allow rooftop access from ground floor, structures a spectacular ‘main entrance’ to the estate from North, while in the same time providing a denser courtyard environment. The lower part of the addition contains flexible rental space and a community house as the communitarian center of the courtyard space and the beginning of the ascending spiral.

3.+Reuse resources/Ground:

The landscape is densified to accommodate intensive green spaces and enable the integration of water management systems into Ellebo’s daily life.

WATER: Water management systems secure rainwater harvesting and (runoff) retention to support evaporation, infiltration, pollutant removal and reuse for gardening.

WASTE: On site waste management at recycling drop-off centers. Composting turns organic household waste into fertilizer for flower and vegetable gardens. ’Clean’ materials from facades are re-used and integrated into pathways and landscape elements. Glasshouses are made of recycled glass panels from the buildings’ facade retrofit.

Social sustainability

The three-fold retrofit strategy is also a strategy for achieving social sustainability, based on social responsibility and local engagement as a means of increasing life quality, while in the same time reducing the environmental footprint.


The continuous roofscape enlarges the green public area while dramatically increasing the experience of walking Ellebo’s ’spiral’ of gardens. A mix of elevated plazas, public, semi public and private spaces makes a little skycity where residents can rent a glasshouse, a garden or a workshop, perform outdoor fitness, socialize, or simply enjoy a 360 degrees Ballerup view.


The indoor climate of the apartments is optimized and their layout is modernized through a simple and cost –effective operation, by creating open eating/living areas towards South and West.

A variety of spatial plug-in modules on the South/West facades secure personalized interface and customized layout for each apartment unit. The plug-ins allow for a bigger differentiation of the apartment layouts to meet the different lifestyles of the residents. In the same time, the open Southwest facades strengthen the contact between indoor-outdoor and provide a feeling of safety.

Furthermore, the plug-in system provides possibilities for outdoor terraces and the integration of greenery within the facades to further personalize the residential units.

Ramps and new apartment layouts at ground floor increase accessibility for disabled people.

3.ACTIVITY/Ground floor

The outdoor areas will be actively and intensely used.

New walkways, a rich variety of different plants and inviting outdoor spaces, encourage different types of activities at the same time.

The new building breaks the characteristic large scale of the existing estate into a number of different and more intimate spaces, and articulates a continuous urban landscape as an uninterrupted promenade sequence which integrates buildings and landscape, uniting ground and roof floor areas into a leisure and production walkable continuum.

Client: KAB Housing Association (Københavns Almindelige Boligselskab), Nordic Innovation

Program: 20.000m2 retrofit of Ellebo public housing estate + 5.000m2 additional program including penthouses, duplex and atelier apartments, community house

Year: 2013

Location: Ballerup, Denmark

Team: Serban Cornea, Kristina Adsersen, Marcin Kruk, Michele di Marco, Mara Horj, Denisa Petrus, Sara Dominguez

Status: Nordic Built international competition; a Nordic initiative intended to accelerate the development of sustainable Nordic building concepts and part of the Nordic Cooperation Programme for Innovation and Business Policy 2011 - 2013