Lumi means “light of life” in Latin, and when the Swedish Food Agency vacated the Hugin block in Uppsala, Vasakronan was left with an office building that was anything but luminous. Low ceiling heights, small windows and poor insulation meant demolition long seemed the obvious choice.
Today the drab 1970s complex has been transformed into a desirable, expressive office building in central Uppsala. The atrium shows why. A lift shaft has been clad in reclaimed roof sheeting, and the many timber surfaces bring warmth to the interior.
In 2015, Vasakronan announced an architectural competition. Anders Tväråna and his colleagues at White Arkitekter proposed that parts of the building should be retained, but their entry did not win. Demolition plans dragged on, and meanwhile Vasakronan's sustainability work had gained momentum.
“Our initial plan was to demolish and build new, but at the same time we began looking at how we could reduce our carbon dioxide emissions. That's when we started to question whether it really was right to demolish the entire building,” says Anna Denell, Head of Sustainability at Vasakronan.
White was commissioned to investigate how much of the existing building could be retained. One of the major challenges was the foundation. The building stands on Uppsala's deep clay deposits, and the foundation could not support unlimited additional load.
The solution was to make the building lighter. By replacing the old concrete façade with a steel structure and adding infill walls with timber studs, it became possible both to install larger windows and improve the insulation.
“We realised that if we removed the heavy concrete façade, we gained a weight margin that allowed us to add three storeys while retaining 80 per cent of the concrete frame,” says Anders Tväråna.
The new storeys were built with a hybrid frame of timber and steel, with two of the floor slabs constructed in cross-laminated timber (CLT). The roof over the atrium is carried by exposed glulam beams, and the external walls have a timber stud frame. In total, Setra supplied around 1,200 cubic metres of CLT and glulam to the project.
“By using lightweight materials like timber, we could add several storeys without having to reinforce the foundation,” says Anders Tväråna.
Weak legislation holds back timber
The Lumi reuse project has won international acclaim and is one of the most highly rated office buildings in the world. According to Vasakronan's calculations, they have managed to halve their emissions compared with demolishing and constructing a new timber-framed building.
“Vasakronan's goal is to reach net-zero emissions by 2030, which requires drastically reduced emissions from building production. The decision to retain the existing structural frame at Lumi, rather than demolish and build new, was a direct consequence of these sustainability goals and ambitions for circular construction,” says Anna Denell, who believes Sweden was long at the forefront of sustainable building.
“We were one of the countries that had come furthest in openly reporting emissions in building processes. But now we've been overtaken by Finland, Denmark and the Netherlands, for example.”
Since 2022, the climate impact of building must be reported–but there are still no limit values for how high emissions may be. According to a proposal by Boverket – the Swedish National Board of Housing, Building and Planning, limit values are not due to come into force until 2030.
“I believe we would see significantly more timber construction in Sweden if the mandatory limit values, which were planned for summer 2025, had been introduced,” says Anna Denell.
A world-class reuse project
Retaining 80 per cent of the structural frame and the entire foundation has delivered the single greatest climate benefit. But reuse of kitchenettes, radiators, glass partitions and large quantities of building materials has also contributed to reduced emissions. Some components come from the building itself, others from nearby refurbishments. In total, around 1,300 tonnes of material were reused.
“Vasakronan's approach in this project was that we would try to reuse everything we could. Even though we didn't know from the start exactly what would work, we tested it,” says Anna Denell.
Reusing on a large scale requires storage space, digital systems and a great deal of hands-on work. Particularly when it comes to salvaged doors. Each door must fit its new location, meet fire and acoustic requirements, and often be adapted or refurbished in a joinery workshop.
The plasterboard, by contrast, was considerably easier to handle. Before dismantling, several companies were invited to demonstrate how plasterboard could be removed without being damaged. The company deemed to have the best method used, among other things, a large magnet to locate the screws in the walls. In total, around 100 tonnes of plasterboard were reused.
“Plasterboard is a very rewarding bulk material to reuse. It usually comes in standard sizes, and when you reinstall it you can turn the inner side, which is often in mint condition, to face outward. What's more, the working environment is better during dismantling because there's less construction dust,” says Anders Tväråna.
Bulk materials and fixtures are precisely what Anna Denell believes the property sector must get better at not throwing away. When an office space gets a new tenant, perfectly functional fixtures are often ripped out for aesthetic reasons.
“It might be the wrong colour of carpet or tiles in the toilets. The items aren't technically worn out, but they're discarded anyway. If you do that with every tenant fit-out, the climate impact over time becomes significant.”
Another important lesson was to first build half a storey as a test. There, the project team could see how the reused components worked together, both technically and visually. The space also became a showroom for potential tenants.
“Many people still think reused means poorer quality, or that it will look second-hand. It's very much about changing people's attitudes,” says Anna Denell.
Text: Gustav Schöön Photo: Måns Berg/ White arkitekter
