1950s building rehabilitated using circular principles

Kristian Augusts gate 23

A stone’s throw from the Royal Palace and the National Theatre in Oslo, lies Kristian Augusts gate 23, dating from 1951. When its rehabilitation began in 2019, the goal was to preserve as much of the building’s distinctive features as possible.

Facade of an old office building in stone in the evening with a dark blue sky.

Facts about the project

  • Place

    Oslo, Norway

  • Contractor

    Hoegh Eiendom

  • Photographer

    Arild Danielsen

  • Status

    Completed

  • Size

    7.300 sqm

Office space with pillars of concrete a conference room in the background and working places to the left.
Man in black walking down stairs in white inside an office.

Preserving its architectural and aesthetic character

KA23 was designed by Bjerke and Eliassen, influential in the architectural development of Oslo during the first half of the 20th century. The building originally served as the headquarters for the Norwegian Employers’ Association. The facade had to be preserved, so the task was to transform the classic building of its time into a modern office space, while preserving as much of its architectural and aesthetic character as possible.

However, the project’s intention to preserve the marble walls, dark wood paneling, terrazzo floor tiles, and stucco lustro-treated walls was not solely driven by nostalgic and aesthetic considerations. KA23 was intended to become Norway’s first building with protected status, to be rehabilitated according to circular principles.

Construction site in the city centre

A major road had to be closed at night several times a week when materials were delivered to the construction site. When adding floors to the existing structure, steel beams had to be lifted in with a mobile tower crane, leading to closure of surrounding streets. The new floors also required piling, 22 metres deep into the bedrock. The demolition work was extended when we discovered asbestos, hidden pipes, structures, and chutes. All of this in the midst of the COVID-19 pandemic.

  • Office space with conference room behind glass walls in the background and a lounge space with a brown sofa and some black chairs.
  • Office space with pillars of concrete a storage cupboard in grey in front of a landscape with workplaces.
  • Two long conference tables with a lot of charis made of wood. Windows in the background and long beige curtains between the windows.
  • Close up of a wall made of stone with a wooden elderly door on the left side and a lamp placed on the wall on the right side.
  • Office space showing an open space with a floor made of squares in black and white stone. Big windows and black chairs in groups.
  • Office space with walls of concrete, grey floor, a big screen on the left side. Big green plants and a bench.
  • Office space showing a lounge area with sofa and chairs, pillars of concrete and a conference room in the background.
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But the result was worth it

Greenhouse gas emissions have been reduced by more than 50% compared to a typical new building. The original single offices and thick inner walls were demolished, allowing daylight to flood in. We restored the teak windows, raised the ceiling height, replaced the window panes, cleaned the facade, sowed green roofs, and adapted fittings and railings on the terraces to meet modern safety requirements.

While the meeting room on the eighth floor has been restored with original features, the rest of the building’s structure has been exposed as raw concrete construction, providing a modern contrast in the interior.

Since the goal was to preserve original details, we conducted a thorough assessment before proceeding. This resulted in us reusing 80% of the building materials, and more than half of the new elements we added, are designed to be reused.

Ensuring sustainable development while respecting cultural heritage

Sweco offers expertise in transformation architecture by blending historical preservation with modern design.

With a multidisciplinary team, Sweco can provide tailored solutions that balance functional requirements with the unique characteristics of each site, fostering a respectful relationship between existing structures and new developments.

Read more about Sweco’s offer within transformation architecture.

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