A circular carbon bank

Nearly 80 meters tall, TRÆ is the first timber building of its size in Denmark. Apart from the load bearing timber construction, the building design is based on wide-scale implementation of reused resources and material innovations. Thereby local waste streams become valuable resources in new building components such as windows, facades and floors.


The vision behind the three connected buildings of TRÆ (tree in Danish) was to build Denmark’s tallest timber structure. The primary structural building material is wood and for every m3 wood used one ton of CO2 is stored (1). TRÆ will be a sustainable office building. It will both contain a work environment designed specifically with physical and mental health in mind and play an active role in fostering a lively and inclusive urban life of the area. The open ground floor is designed to invite passers-by and the local community inside to contribute to the daily life of the buildings. Plants, green rooftops and a miniature forest of adopted trees at street level level contributes to a healthy environment. The large green roof space on the top of the two lower towers will be the heart of the building and a centre for social encounters, as well as a kitchen garden for the canteen kitchen. The ambition is to attract users who put an emphasis on community building and have business concepts true to the building’s ethos which can contribute to the continued development of TRÆ.

TRÆ consists of three buildings: T1 is a tower of 20 stories, T2 and T3 are 6 story buildings. The plan geometry is defined by three circles cut to size by the borders of the site. Thereby the buildings have asymmetrical ground plans with convex facades towards the inside of the plot and flat facades towards the streets, creating a building ensemble that looks very different from each angle. The buildings are interconnected by a pedestrian bridge running from street level up to the publicly accessible Kulkranbro, a new high-rise public space connecting the site with Aarhus’ central station. The buildings’ load bearing system consists of concrete cores, CLT floor decks and timber columns, thereby contributing to significant CO2 savings compared to conventional concrete structural systems.

The ideas and concepts behind the conception of TRÆ are not limited to creating a more sustainable building. It is about rethinking our preconceptions and challenging the status quo in the journey towards creating a truly sustainable built environment. By addressing issues relating to social inclusion, energy use, resource efficiency, biodiversity, water use, health and new building practice, TRÆ aims to demonstrate how a holistic approach can provide solutions reaching far beyond its own sphere.


(1) Arno Frühwald, University of Hamburg

‘If we can do things differently, we can help accelerate a movement. This is what we are trying to accomplish with this project. We are all in. We truly believe there is a demand for this type of building from businesses. This type of building and living sustainably will become a part of their DNA. ‘

Michael Bruhn

Director, PFA Real Estate

‘The purpose of this collaboration is to gain knowledge and know-how about sustainable solutions. In this way we will be part of accelerating the transition of climate change mitigation of the building industry in Aarhus.’

Bente Lykke Sørensen

City Strategic Chief, Aarhus Municipality

‘The district south of Aarhus is a vibrant urban development area where we are trying to advance the scenery of entrepreneurs, artists and socially vulnerable citizens. This is why an ambitious project like TRÆ fits perfect into this area.’

Bente Lykke Sørensen

City Strategic Chief, Aarhus Municipality

  • TR3_opstalt
  • TR3_plan


Aarhus, Denmark


14.850 m2




Landscape Architecture
Product Design




Kilden& Hindby
PFA Ejendomme