Stora Enso has created a new HQ that sits within the largest mass timber building in Finland – Katajanokan Laituri – and used its readymade Sylva™ range to produce a landmark sustainable structure.
The building is set in a culturally sensitive part of Helsinki, surrounded by 200-year-old remnants of Finland’s empire era, including churches and cathedrals that need to remain visible to protect the city’s cultural heritage and ensure its architecture stands out to citizens and visitors alike.
As well as planning restrictions affecting the size and shape of the structure, the position of the building on the pier presented another challenge for the architects Anttinen Oiva Arkkitehdit and structural engineering firm Sweco Rakennetekniikka. Their preparations had to be watertight from the basement of the building upwards to protect its structural integrity. Fortunately, the planning was meticulous and the execution just as impressive.
From blueprint to reality
When construction began, project managers at Haahtela Oy had to contend with the congested urban environment of Helsinki, which has a similar population density to Bournemouth. For ensuring the project was conducted with minimal disruption, Stora Enso’s Sylva™ kit of parts was used, which meant that millimetre precise measurements and assembly happened ahead of their arrival on-site. Only 171 just-in-time deliveries were needed to deliver more than 2,000 bespoke load-bearing wooden elements, cutting down on carbon emissions from transport. This meant five times fewer deliveries compared to using concrete, thanks to the lightweight character of wood elements, significantly reducing both logistical complexity and the environmental impact associated with construction.
These elements included 5,940m³ of Sylva™ CLT walls, stairs, floors and roofing from Stora Enso’s Gruvön Mill in Sweden, 1,690m³ of Sylva™ LVL beams and columns from its Varkaus Mill in Finland and 97m³ of exceptionally strong engineered wood, Effex® Dura to support the building’s 700 windows, weighing 210 tonnes.
The use of Sylva™ kit of parts had benefits beyond reduced deliveries. It enabled a level of efficiency that will have those familiar with timings for UK infrastructure projects left in disbelief – the whole wooden frame of the building together with prefabricated facade elements were erected in just seven months and the entire schedule was accurate within two days.
Antto Kauhanen, Business Development Manager at Stora Enso who worked on the project said: “There is a Sylva™ kit of parts for everything, whether it’s a floor, wall, column or beam. We can provide that solution to contractors, developers, architects and engineers whether they need to build apartment blocks and industrial buildings or hotels and offices.”
The mixed-use building concept means developers do not need to commit to the structure being a hotel or an office for its whole lifecycle. In fact, Katajanokan Laituri was designed to allow easy adaptation so that the hotel and office areas can be rearranged according to future needs. This offers unrivalled flexibility for investors and developers, which in the case of Katajanokan Laituri is Varma Mutual Pension Insurance Company. Critically, it also cuts down carbon emissions generated by unnecessary demolition if needs change in future.
Sustainable by design
Using wood instead of concrete for the structure resulted in an impressive 35% reduction in upfront carbon emissions. On top of having a lower carbon footprint than concrete, wood also stores carbon. No other commercially available building material can do that. The wooden elements used in the construction captured 6,000tonnes of CO₂ during the trees’ growth and are now storing it in the building for at least the next 100 years.
The biophilic design of the office – aimed to bring the outside in – draws on the natural world to provide power and enhance the design in a sustainable way. From the natural materials and lighting inside to the green roof and solar panels on the rooftop to generate electricity the building is a great example of sustainable architecture. The benefits go beyond the environment at large and have been conceived with the occupants in mind – whether they are the Stora Enso staff working in the office, visitors to the Solo Sokos Hotel Pier 4, or members of the public visiting one of the several cafes and restaurants or simply there to admire the architecture.
Nature’s touch
In addition to the sustainability benefits provided by mass timber, it combines with a range of other materials including a plethora of plants, a small forest in the courtyard and gentle lighting inside the Katajanokan Laituri building to promote well-being. The design decisions were taken to help increase productivity and reduce stress levels – important features in countries where people may spend up to 90% of their time indoors.
Stora Enso saw this as an especially important example to set in their head office. Kauhanen explained more: “There was a lot of scientific research that went into how the building will impact users and we’ve developed this in a way that increases well-being. I know from my own experience in the building as well as conversations with others who have visited that the air quality is great – it’s easy to breathe, it’s fresh, and it smells good. The surfaces, whether it’s a column or wooden wall, make you want to run your hands along it and experience the smooth finish. All these things may be small factors alone, but they combine to make the building a place where people want to come, and that’s exactly what we want for our office.”
Leading by example
Stora Enso has delivered over 23,000 projects around the world, so it is by no means the first mass timber feat, but it stands as a physical and visual testament of the company’s purpose and values as a leader in renewable materials. Kauhanen explained its importance: “We know developers, architects and engineers are driven by a sustainability agenda and we want to show a shift from using traditional materials such as concrete doesn’t have to be a burden. In fact, it opens a range of new possibilities for buildings that bring together the best of people and planet.”
ST Awards 2024
Stora Enso made its mark at the 2024 Structural Timber Awards, with the prefabricated Sylva™ kit of parts powering several winning projects. WorkStack, designed by dRMM, took Solid Wood Project of the Year and Architect of the Year. Engenuiti & Integral Engineering Design earned Engineer of the Year for Haileybury SciTech, with Haileybury Independent School named Client of the Year. “Our prefabricated wood-based products for low-carbon buildings were also essential in several shortlisted projects with our partners B&K Structures and EURBAN Limited. This success truly highlights the growing influence of using sustainable mass timber elements in the UK construction sector,” says Mila Duncheva, Business Development Manager UK, Stora Enso.
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