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Hotel apartments in Copenhagen - Value Engineering

Photo: Lundgaard & Tranberg

​On a narrow site in Østerbro, Copenhagen, H.S. Kryolitentreprise A/S is constructing a high-rise, Charlottetårnet, with 37 hotel apartments. COWI has designed and optimized the high-rise and is in charge of all the engineering disciplines.

​The Danish architects Lundgaard & Tranberg have designed the new high-rise that will be located next to the housing block, Charlottehaven, in Copenhagen. The 16-storey building will hold 37 furnished hotel apartments. Being of high architectonic quality, the building will be made of only the best materials.

Narrow site challenges construction

The building will sit on a narrow urban site of merely 475 square metres, which enforces high demands on the coordination and timing of the works and lays down requirements for the solutions. 

To fit into the modest site and to justify the construction of a high-rise at this location, the building has a narrow and slender design, with a distinct tower shape. Because of the building's narrow, yet relatively high shape, achieving structural stability poses just as many challenges as considerably taller buildings.

Vibrations and deformations are some of the special challenges attributable to the slender design. To come up with solid solutions in terms of both structural behaviour and practical execution, COWI carried out finite element method (FEM) calculations in 3D.

Special prefrabricated floors and slender columns

COWI designed and optimized the building in an integrated Value Engineering process, which has met the client's high requirements for quality and project economy.

One of the measures introduced to secure optimum space in the small apartments is the use of specially designed prefabricated floors.

The prefabricated floors are designed to eliminate the use of structural topping, in turn freeing more head-room in the apartments. Another benefit from the special floors is the need for only a few slender façade columns.

Energy-optimized building

The project vision is to create an energy-optimized residential building that on the whole will be self-sufficient in terms of energy for heating and cooling.

The concept builds on experience from, e.g. the Royal Danish Playhouse in Copenhagen, and makes use of thermo-active concrete structures – in this case the special designed prefabricated floors that are well suited as thermo-active floors. The primary energy source is geothermal energy, which is extracted from a series of boreholes reaching 130 metres into the ground.

More about floors and columns

Specially designed prefabricted floors are structurally combined into one deck per storey, thereby acting as one continuous deck diaphragm. This allows for the handling of vast horizontal shear forces, eliminating the need for structural topping.

Where necessary, the special floors will feature embedded beams, while insulation material will be added in other places to limit the dead load and material consumption. The result is an optimized, sustainable design.

As the floors act as one continuous deck and the dead load is limited, the number of column supports can be limited to only a few slender 200x200 mm steel profiles. The columns are composite, i.e. a combination of steel and concrete, which is a robust and fireproof solution. In ultimate limite state  (ULS) the overall steel area would be active, whereas in accidental fire events (ALS) the concrete protected steel 'core' ensures the structural integrety. 

LAST UPDATED: 03.08.2017