Sustainability is the driving ambition for the development of Trælasten in Aarhus. In less than ten years, the former industrial ground will be transformed into a mixed-use neighborhood with 700 housing units and 14,000 square meters retail and offices. The entire area will be certified with DGNB Platinum, while all the buildings must be certified DGNB Gold.
CASA is a turnkey contractor on the project, which is being built for Pension Danmark. The project sets new standards for sustainability with the recycling of old building materials and a thorough investigation of new building materials from a Life Cycle Assessment perspective.
Old materials find new uses
The old domicile of the DT Group is being renovated for new purposes, while the other buildings on the ground are being carefully dismantled. The materials are sorted, analyzed, and all the hazardous materials discarded. The reusable materials are catalogized and stored at the construction site for future use. The large glulam rafters from the old halls will be recycled and used in the load-bearing structures in the new houses, while the old brick facades will find new use as floor panels, and the old roof tiles used as new facade cladding.
Life Cycle Assessment
Trælasten cannot be built with recycled materials alone. Going from 11,000 built square meters to 70,000 square meters requires the use of new materials. To find the most sustainable building materials, the architects, engineers, Pension Danmark, and CASA performed Life Cycle Assessments on different building materials and designs. Everything from the construction and facade cladding to the floor construction and bathrooms has been up for debate.
The analysis showed that the largest CO₂ savings could be made going from heavy to light constructions in the facade, but also the last layers have an impact on the emissions. Going from a 2 mm aluminum facade cladding to 0.5 mm has a tremendous impact. In the same way, there are big differences in the CO₂ footprint of a brick depending on how it is manufactured. From a CO₂ point of view, the best solution is to use wood in the construction of the facade, but wood has difficulty living up to the fire and sound requirements. Therefore, the materials must be combined to have the best effect in multi-story buildings over 6 floors. In the terraced houses, all the facades will be clad with wood.
The Life Cycle Assessments have provided new insights into the complexity associated with calculating CO₂ emissions. Most of the crucial choices were made in the design phase. Therefore, the interdisciplinary collaboration between architects, engineers, client, and contractors has been extremely valuable and is worth repeating in future projects.
For more information, contact
Ditte Hejberg Sorknæs
Head of Marketing and Communication