DeepDive: Taking timber construction to new heights

Replacing the concrete frame with a wooden one is a way to drastically reduce a building’s carbon footprint at virtually the same cost. Something more and more people are starting to take notice of. Last year, 33% of White’s projects had timber frames, up from 21% the year before.

Anders Tväråna is the lead architect for one of them: Magasin X in Uppsala – Sweden’s largest wooden office building.

– By choosing a wooden shell, we have managed to cut carbon emissions by about half compared to concrete, says Anders Tväråna, Lead Architect.

Of course, even large-scale construction with a wooden frame has an environmental impact. But it consists largely of the concrete still used in the ground and basement. In Magasin X, the elevator shaft and stairwell are also made entirely of wood. It also uses several innovative sustainability solutions such as local electricity generation with a battery bank and geo-energy to regulate indoor temperatures.

There are really no limits to what can be done with a wooden frame. The key is to understand the properties of the material. Unfortunately, knowledge in the industry is generally not very high, which often leads to half-baked solutions with unnecessary reinforcements in concrete or steel. This is both ugly and unsustainable in the long run, as buildings need to be optimised to use as little material as possible.

– At one point I had to carve out a full-scale prototype of a detail myself at home in the garage, which I took to a meeting to show that it was indeed possible to do as we had proposed. As an architect, you have to be persistent and be able to contribute something to make yourself relevant, says Anders Tväråna.

There are, of course, challenges with timber construction such as fire and acoustics. Then the frame itself has to be designed properly because it is not as flexible in terms of the placement of holes in the joists and beams. Sometimes there is also a lack of wood products from suppliers. But demand is driving development and in the case of Magasin X, for example, the specially designed wooden profile developed for the glass façade has now become part of the regular range.

Magasin X and Sara Cultural Centre are the fruits of long-term work on large-scale timber construction and would not have been possible without the knowledge built up within White over the years. Maria Orvesten is an architect and has been involved in the creation of Sara Cultural Centre from competition proposal to finished building. Now there it is, one of the world’s tallest wooden buildings. How did they manage it?

– Without talented co-consultants and courageous clients who believe in the idea, it would never have happened. There were no ready-made solutions when we started; we had to invent them as we went along, says Maria Orvesten.

The inherent qualities of the material had to be dealt with. To cope with the sound insulation between the hotel rooms, which came as prefabricated modules from the factory, a steel coupling was needed to dissipate the sound energy and handle the step noise between floors. Wood is also a light material, which allows the structure of the higher building elements to sway. This is not dangerous but can be a nuisance for those who will be in the building. To counteract this, concrete was added on top of the beam layers on the top three floors, which reduces the speed of the oscillations.

To create large, open, flexible spaces, such as in the foyers, a hybrid truss with steel parts is used to create the large spans and ceiling height required, which in turn also makes a beautiful detail.

– We haven’t had to compromise on the architecture at all just because we’re building in wood. We have also gained a fantastic indoor environment with the lovely smell of trees that lingers for a long time, a warm impression, and a good sound environment, says Maria Orvesten.

Despite the great strides made by large-scale timber construction in recent years, there are still sceptics. But anything goes, says Maria Orvesten, who says it’s now a question of how, not if, a project can be done in wood.

– Of course it takes knowledge, but it is possible to build both high and with large spans in wood. As a resident of Skellefteå, I am particularly proud to have been involved in this project and to have shown that it is possible! We have managed the wooden building tradition that exists in Skellefteå and taken it into the future. On a personal level, for me as a forest owner, it feels particularly good that a small spruce or pine from my forest may have contributed to this house, says Maria Orvesten.