Award for Denmark’s tallest residential building

The special architectural requirements and the demanding construction schedule called for close cooperation between general contractor Per Aarsleff A/S and PERI. They did not shy away from innovative approaches in their attempt to meet the construction deadline. For example, the ACS Self-Climbing System, which had already proven its worth in numerous construction projects around the world, was used for the first time in Denmark. The rail-guided climbing formwork impressed with its hydraulic drive, large climbing units, high lifting force and fast processes. This meant that a concreting cycle of just one week per floor could be realised: “The close communication with PERI was one of the reasons why we were able to concrete one storey every week,” recalls Uffe Røge, Section Engineer at Per Aarsleff A/S.

A crowning customised solution to a structural challenge

The crowning glory of the “Lighthouse 2.0” had to be added before the turnkey project could be completed and officially handed over. The challenge lay in the fact that the geometry of the upper floors differed from that of the lower floors. It would not have been profitable to erect scaffolding up to the 45^th floor, so a completely new approach to scaffolding construction had to be found:

“We always knew that other means would be necessary for the upper storeys. The large panoramic windows on the 44^th floor as well as the restaurant and the design of the roof terrace required an innovative custom solution,” explains Jesper Scharff Lanng, Site Manager at Aarsleff.

Over 400 engineering hours and 50 tonnes of scaffolding

Major technical calculations had to be carried out to construct the complex apex of the building. All framework conditions had to be considered – from wind and weather to the safety of the workers on the scaffolding and passers-by.

“Erecting scaffolding inside the building that extends to the outside is nothing unusual. But if you’re installing 50 tonnes of scaffolding across four storeys on the 43^rd floor, then that’s a completely different ball game. The amount of scaffolding and the geometric complexity are vast, but you also have to make sure that you don’t damage the building and the facade and take any potential wind loads into account,” says Jesper Scharff Lanng. Sales engineer René Østergård from PERI Denmark adds:

“After discussions with Aarsleff about the options for erecting the scaffolding, we had to think well outside the box. The solution we came up with was to lay steel beams across the 43^rd floor that could support the entire weight of the scaffolding. On the same floor, we built a platform that protruded from the facade and rose 12 metres into the air without touching the building or damaging the facade.”

It took PERI Denmark’s engineers more than 400 hours of work and calculations to create the final customised solution, which, according to the company, was the largest scaffold constructed at this height in Denmark at the time.

Safety at great heights

A fine-mesh net was installed to ensure the safety of both the workmen and the people on the street around 140 metres below the scaffolding: “When you have such a large scaffold at this height, various safety precautions must be taken. For example, we installed an air-permeable mesh that allowed half the air to pass through in order to reduce the wind load,” says René Østergård.

Aarsleff also relied on PERI and the engineers’ technical calculations when it came to safety: “We always have to carry out a comprehensive safety check before we start construction. We had peace of mind that the workmen were carrying out their work safely and that even a small bolt falling over the guardrail would not land on a passer-by from a height of 40 storeys, but would be caught by a net instead,” explains Jesper Scharff Lanng.

An outstanding project

In autumn 2023, non-profit organisation, the Council on Tall Buildings and Urban Habitat (CTBUH), awarded the project the prize for “Best Tall Building” in the “100 to 199 metres” category. The CTBUH is a globally recognised organisation committed to the research and advancement of high-rise buildings and urban living spaces. The CTBUH is also committed to innovative designs and sustainable urban development concepts. The award underscores the global recognition that the project has received as an architectural masterpiece and pioneering achievement in high-rise construction.