The cafeteria of Helsinki’s new secondary school smells like a pine forest, but there is no aromatic air freshener in sight. Instead, most of the five-storey building is made of wood.
The school will not be finished until next year, although many of the interior walls are already covered with smooth wooden panels. Wood has also been used for load-bearing structures to support the floors, and as exterior cladding.
“It is a more sustainable choice,” says engineer Miimu Airaksinen (Miimu Airaksinen), Vice President of Development at the Finnish construction company SRV, which is the architect of the school's construction. “But we also work with wood because it is a pleasant material; people appreciate and enjoy wood and wood design.”
This project is part of a growing trend in the Finnish construction industry. Developers are increasingly swapping popular materials like concrete and steel in favour of wood. This is linked to the country's ambitious efforts to achieve carbon neutrality by 2035 and become a leader in Europe’s circular economy.
As three-quarters of Finland's land is covered by forests, timber is a readily available material here, yet specific regulations must be followed for its use in medium-rise and taller buildings. In Finland, where detached houses and summer cottages are common, the public is less concerned about the risk of fire than in other parts of the world where timber is not as common as a building material. However, questions about fire safety remain, especially in taller buildings. There is plenty of evidence that timber structures, known as CLT (cross-laminated timber), can withstand fires better, emphasises Miimu Airaksinen, because they are designed to endure high levels of heat and collapse more slowly than concrete.
On the building site of the school's upper block, her team is busy cutting CLT panels, which are produced by joining layers of wood panels at right angles. “You make the timber stiffer this way, so the wood becomes much stronger,” she explains. Technology such as CLT is environmentally friendly, including being much lighter than many other building materials, so less heavy machinery and energy are required during construction. Building can also be faster, as there is no drying phase, as is the case with concrete.
Moreover, wooden buildings actually remove more carbon dioxide from the atmosphere than they emit; they can store the carbon absorbed by trees from the atmosphere over a period of fifty or sixty years. By contrast, steel and concrete leave a massive so-called carbon footprint.
“It can really help us in the field of climate change,” says Ali Amiri, a sustainable buildings researcher at Aalto University near Helsinki and a former civil engineer. “If we compare wooden buildings with other buildings, such as concrete, steel or even brick buildings, then [the wooden buildings'] greenhouse gas emissions are 20 to 30% lower. So, they are a very good message in this context.” According to research conducted by his team, if 80% of new residential buildings in Europe were built of wood, they could store up to 55 million tonnes of carbon dioxide annually. That is equivalent to nearly half of the annual emissions produced by the European cement industry.
Such timber structures as CLT have been used in Europe since the 1990s, but they have seen a revival in Finland thanks to a government-backed wood construction programme, which aims to ensure that wood is used as the primary material in 45% of public buildings by 2025. Developers can apply for grants and receive assistance with tasks such as procurement and risk communication. “I think every company is building wooden buildings today,” says M. Airaksinen. “There is pressure to ensure sustainability.”
In the secondary school, plasterboard, which is made from limestone and is not highly flammable, is being used to add an extra layer of protection to the interior walls on the upper floors. “We have to take fire safety seriously,” says Miimu Airaksinen. “We also conduct fire drills and structural strength tests, so that in the event of a fire, there is the knowledge and skills of what to do and what to expect.”
The trend of using wood in construction is also becoming relevant in the private sector. Data from the Finnish Forest Industries Federation show that it is already the primary material for 4% of apartments and 16% of commercial buildings.
For example, the headquarters of the Finnish game developer Supercell is located in Helsinki’s Wood City district. And in the centre of Helsinki, it is a new quarter with hundreds of new wooden apartments.
In the Supercell headquarters, massive wooden carved figures and specially curved wooden panels create an impressive reception area, while wood adorns the walls of the eight-storey open-plan office spaces, cafes and other rooms. Meanwhile, the cybersecurity company WithSecure is building a new office next door in collaboration with SRV and Stora Enso, the largest Finnish timber producer.
And perhaps least surprisingly, in a country where people love to sweat in saunas, one of Helsinki's most popular leisure facilities is a massive wooden sauna and restaurant complex. The Löyly complex, which opened in 2016, has won several world-scale awards for its striking, cloak-like wooden structure, which allows visitors to climb onto its sloping roof.
Environmental campaign groups, such as the World Wide Fund for Nature, have raised concerns that the increase in wooden building construction could put too much strain on the planet's forests.
“From a climate perspective, it is a good way to store carbon, but on the other hand, we are increasing the overall level of consumption of natural resources,” says WWF's leading forest expert Maija Suominen. “Because obviously, we also need other wood products, such as paper or packaging material, and if we plan to increase the production of other products, we increase the volume of logging.”
Finnish woodworking companies are committed to carefully and sustainably replanting harvested areas. However, M. Suominen argues that there remains a risk of a decline in biodiversity if production increases in the future, which could affect both animals and people.
“Then forest processes collapse at some point, and they are no longer as resilient to respond to the changing environmental conditions caused by climate change. We will face higher rainfall, droughts and insect infestations in the forests.”
Sustainability expert Nani Pajunen (Nani Pajunen) from the Finnish Innovation Fund Sitra agrees that it is important for construction companies in Finland and abroad not to simply hide on the wave of the so-called wooden building trend, trying to look more environmentally friendly. She argues that it is much more important for companies to broadly evaluate the carbon dioxide emissions of their production processes and the different life-cycle potential of materials.
Other recently introduced innovations designed to improve sustainability in the industry, such as recyclable concrete and steel, could be more durable than wood in large-scale projects, such as very tall apartment buildings, public buildings or bridges.
“It is not just a black-and-white question of which [materials] are wrong and which are right,” the expert argues. “It is about the attitude. If you are an engineer in the construction industry, you have to think about how to use materials more sustainably.”
Despite concerns about environmental protection, the wooden building industry is developing, especially as other Nordic countries, Germany, Canada and the US have increased production in recent years.
The “grey line” of the presentation
Market research company Fortune Business Insights recently valued the CLT market at 806 million US dollars (715 million pounds) and predicted that it would grow by 14% by 2028.
In connection with the war in Ukraine, which raised global steel and energy prices, expert A. Amiri says that his research team has also observed a sharp increase in demand from companies and decision-makers from all over the world. Although A. Amiri predicts that wooden building construction in Europe and North America will “certainly increase” in the coming years, he points out that constructing high-rise projects from timber is still “somewhat more expensive” than using other, more commonly used materials. Therefore, he believes it might be harder to persuade countries that have access to cheap concrete and steel to change this approach.
Back among the loaders and diggers that continue to transform the SRV school building site, Miimu Airaksinen says she expects the wooden construction industry to grow alongside the development of new low-carbon materials.
“We are focused on building sustainable buildings and life-cycle-smart buildings,” she emphasises. “That is the future.”