A natural construction kit
Office building HasleTre in Oslo was awarded the title of Norway’s “Timber Building of the Year” for good reason. With a visionary concept by Oslotre, it can be dismantled like a box of toy building bricks and is made predominantly of nature-based materials.
Earth to earth, ashes to ashes, dust to dust. This familiar phrase is often read from the Book of Common Prayer while mourners are gathered around an open grave. From a certain perspective, it can also be interpreted as an early affirmation of closed-loop thinking. The modern-day principle “Cradle-to-Cradle” actually means the same thing: materials become new raw materials after they have reached the end of their current lifetime. Nature leads by example here, where everything is used without leaving any waste. The strategy aims to reduce future carbon emissions, waste volume and resource consumption. In the best-case scenario, this means an entirely closed-loop cycle that avoids the mountains of waste created by our current take-make-waste model. An innovative timber construction built on the edge of Oslo city centre comes very close to this circular ideal. Called HasleTre, its rough shingle facade actually looks very like tree bark.
The construction is made of wood from the inside out and is planned as a dismantled and reusable kit.
Oslotre, architectural studio
“The construction is made of wood from the inside out and is planned as a dismantled and reusable kit,” explains Oslotre, the architectural studio responsible for the design of HasleTre, and also the striking timber building Lumber 4 on the Norwegian coast. HasleTre is an office building with 3,000 square metres of space on five floors, including a basement and rooftop terraces. The 5x5m grid for the wooden construction enables flexible room solutions ranging from individual offices through to open-plan workspace.
Design strategies to conserve resources
Both the primary construction, i.e. the horizontal beams, and also the secondary construction, i.e. the supporting walls and posts, are made of timber in large standard formats with minimum offcuts. “This design strategy enabled almost no material waste in production, maximizing transport volumes and speeding up the assembly,” Oslotre continues.
The wooden connectors result in a construction system that leads to a documented reduction of steel use of more than 70% throughout the building.
Oslotre, architectural studio
A further design strategy was to adopt purely wood-to-wood joints for construction parts. The glulam columns and beams are joined with beech dowels, while assembly of the CLT walls and slabs uses X-fix connectors. “The wood-to-wood joints result in a construction system without the need for steel or aluminium joints, which leads to a documented reduction of steel use of more than 70% throughout the building,” the architects explain.
Inside the building, the planners also saved resources wherever possible and reused sanitary installations, ventilation aggregates and acoustic ceiling plates. “60% of the furniture is upcycled, and 40% is made with biodegradable materials or from industrial waste like plastics harvested from the ocean.”
Constructed in nine months
The essence of this wooden building is a construction with maximum simplicity, together with single-material connectors. According to the architects, this simplifies future adaptations. Right from the outset, disassembly at the end of the building’s lifetime was integrated into the design. However, this circular pilot project also caused problems for companies involved. As Oslotre recalls: “The project required a collaborative effort from everyone involved, including developers, contractors, and planning authorities. It proved a valuable learning experience for all parties and there is a desire to inspire others to think about reuse.”
Short assembly time is known to be one of the biggest advantages of modern timber construction. HasleTre was ready for occupation in a record time of only nine months.
The staff at Save The Children Norway, who moved into their new headquarters, also benefit from a healthy environment.
Nature-based materials
Besides the natural wooden surfaces, the office also uses cork and wool as nature-based materials. “By taking advantage of the hydrothermal properties of these biological materials, the building aims to reduce energy use,” the project description reads. “It is also designed to enhance the tenants’ sense of joy, concentration, and reduction of sick leave.”
Architectural studio Oslotre has amassed a wealth of timber construction expertise. The company founders are familiar with this natural building material from their time as manufacturers with a CLT factory. And their projects are regularly awarded renowned prizes: HasleTre was named Norway’s Timber Building of the Year in 2023.
Text: Gertraud Gerst
Translation: Rosemary Bridger-Lippe
Photos: Einar Aslaksen
