The TRÆ highrise collects circular experiences

TRÆ will be the new landmark in Aarhus and in a debate at the fair Building Green, project participants shared their experiences from the 78-metre tall building, which is a pioneering example when it comes to circular construction. The debate was facilitated by We Build Denmark – with Troldtek’s new Manager Circular Solutions, Darma Louise Duus, as moderator.


The session on the TRÆ highrise was delivered from the Main Stage to a packed audience on Thursday 11 April at Building Green in Aarhus, Denmark. Four of the project participants shared their experiences from the project at Sydhavnen in Aarhus, which will be the largest hybrid wood building in Denmark. The developers, PFA Pension and Kilden & Hindby, have gone all-in on circular solutions.

Darma Louise Duus, the new Manager Circular Solutions at Troldtekt A/S, confidently moderated the conversation on the subject of TRÆ. Her previous employer, the industry cluster We Build Denmark, organised the session.

The panel on stage included:

  • Henrik Kjærgaard-Phillipsen, Project Manager at Kilden & Hindby
  • Christian Fundby Schou, Head of Advanced Product Development at DBI – Danish Institute of Fire and Security Technology
  • Christian Wittrup, Marketing and Relations Manager at a:gain
  • Jan Rohde, founder of Greendozer

Floors dedicated to experiments

TRÆ is an innovative and ambitious project that showcases how circular development can be achieved when there is a willingness to collaborate. The aim of the session during Building Green was to have a focused discussion on the solutions in the project so that others can copy and learn from the development.

A large amount of recycled materials have been used for both the exterior and the interior of TRÆ and three of the 20 floors are even dedicated to experiments using materials: one floor has been constructed entirely using recycled materials, one floor has been constructed using bio-based materials and one floor has been constructed using upcycled materials.

Reused Troldtekt acoustic panels delivered by Green Dozer as direct reuse were selected for the reuse floor. On this floor, the flooring has been created using materials from demolished apartment blocks at Gellerup Park in Aarhus.

Greendozer and a:gain supplied recycled and upcycled materials for TRÆ and both were able to explain the importance of including contractors in the material selection process. Christian Wittrup from a:gain also spoke about the practical quality checks performed at the building site and highlighted the importance of the industry continuously contributing materials for recycling and upcycling to ensure that circular solutions remain sensible business decisions.

From a roof in Herlev to a facade in Aarhus

One particularly spectacular element of TRÆ is the facade, which is clad in disassembled aluminium roofing sheets from a general residential building in Herlev. The aim was to use wood, but this was not possible for fire-protective reasons. DBI therefore conducted extensive testing of the facade model using roofing sheets.

Henrik Kjærgaard-Phillipsen explained Building Green how the risk of reusing the old panels was thoroughly evaluated. The reused panels have an expected remaining service life of 80-100 years and the placement of the panels take into account that later on, it will be easier to replace them on the lower floors .   

The many audience members moved from the hall to the exhibitions at Building Green having picked up many specific pointers about circular developments in practice.

Read more about TRÆ and the choice of materials in our feature article. This includes an interview with Henrik Kjærgaard-Phillipsen.

FACTS: About Building Green Aarhus

  • More than 3,000 visitors attended Building Green Aarhus.
  • The event took place on 10-11th April 2024 at Aarhus Congress Center.
  • There were around 80 exhibitors and 80 speakers across three stages over the two days.