Wood, with its capacity to store CO2, is all the rage in the construction industry. It is even being used to build skyscrapers. Swiss expertise is flavour of the month. Demand is growing, but tensions lurk beneath the surface.
The Geneva engineering and wood design firm Charpente Concept is a mecca for woodworking. The firm, founded in 1991 by master carpenter Thomas Büchi, designed the Broken Chair at Place des Nations in Geneva, made the Goûter Hut on the slopes of Mont Blanc out of wood and came up with the Palais de l’Équilibre, the massive wooden sphere presented at the Swiss National Exhibition in 2002 before being installed at CERN. This firm’s other point of pride is that it was enlisted in the wake of the fire at Notre-Dame in Paris to carry out a technical analysis of the cathedral’s nave in preparation for its reconstruction. The firm looked into archives 600 years old, a real immersion into the Middle Ages, when 20 years could go by between when wood was cut and when the resulting beams were fitted.
“Wood is reclaiming the place it used to hold centuries ago, before it was replaced by steel and then by concrete. People had forgotten its qualities as a material,” says Rafael Villar, vice-president of the company. He qualified in 1996 and still remembers starting out in the industry, when proponents of wood were considered eccentric. Granted, the firm in question had just erected a wooden exhibition hall 300 metres in length in Geneva, but most of its orders were for chalets and a few gym roofs. Today, wood is used to build residential buildings. “Over the past 30 years, the delivery turnarounds for some parts have more than doubled,” notes the Geneva native. This is a sign of high demand. Ultrasound is used to define the resistance of parts before they are processed. Digital machines are used to cut them to size.
The bank UBS has set its sights high. The proof is in the tower it is planning in the district of Altstetten, in Zurich. The tower, scheduled for completion in 2031, is to be 108 metres tall, making it the tallest wooden tower in the world. Unless, that is, another project overtakes it: a wooden skyscraper planned for Basel for the same year, as a building for the Bank for International Settlements. It will be 122 metres high! (SH)
On construction sites, prefabricated wooden parts can be assembled considerably more quickly than mineral walls. “Wood is light, which makes it suitable for taller constructions,” emphasises Sébastien Droz, spokesperson for Lignum, the umbrella association for woodworking professions.
We are even entering the era of wooden skyscrapers. In the Lokstadt district of Winterthur, the Rocket Tower is set to be 100 metres high. “It is one of the tallest wooden residential structures currently planned,” according to Ina Invest, the building developer.
The tower will need 3,300 cubic metres of wood to build its load-bearing structure. “We will be using beech and spruce from Switzerland and neighbouring countries,” says spokesperson Stephan Meierhofer. “Wood is very sturdy and, even in the event of a fire, retains its load-bearing capacities for a long time,” he explains. Construction is set to begin in spring.
Even taller will be a tower planned by UBS in the Altstetten district of Zurich. The skyscraper will be 108 metres tall when it is completed in 2027, making it the tallest wooden building in the world. Its offices will house 2,800 employees. Wooden buildings are also going up in French-speaking Switzerland. The Tilia Tower (Latin for “lime tree”), on which construction began in 2024, will combine wood and concrete. It will capitalise on the strengths of hardwoods, like beech, which are sturdier than softwoods. This 85-metre building will be built in the Prilly district in the east of Lausanne. Close by, the Malley Phare Tower is to be constructed on an existing building. The 2,000 cubic metres of wood required for this residential building come from fir and spruce, 95 per cent of which comes from Switzerland. The tower is set to be completed this year.
“What is the best way to use wood with regard to the environment and biodiversity? That is the question,” according to forestry engineer and emeritus professor in wood sciences Ernst Zürcher. One cubic metre of reinforced concrete generates between 350 and 400 kilos of CO2, whereas a cubic metre of wood traps 1,000. “However, instead of using cubic metres of wood to create spectacular structures, a better idea would be to use it in square metres,” he says. In other words, wood could be used to cover surfaces instead of forming the framework of very large-scale construction projects. The specialist cites the example of the stone walls of Grisons houses, where wood is fitted to the interior walls, significantly improving the home’s insulation and comfort. This approach could be adopted to insulate part of the estate: apartment blocks, industrial buildings, schools, etc. “Building new skyscrapers is a thing of the past, an expression of power. We should really renovate existing ones, by using the valuable medium of wood to make them comfortable and biocompatible,” the expert argues.
Switzerland has a unique law governing its forests, dating from 1903. “We cut down the forest in order to maintain it,” says Rafael Villar, who underlines the fact that the cost to local authorities of maintaining forests is not balanced out by revenue from wood. The trick is cutting down trees strategically, as for a gymnasium project in Aigle (Vaud), with which his firm was involved. The firm selected trees in the forests of Vaud colonised by bark beetles, an insect that feeds on sap and whose presence exposes the bark to a fungus that can turn the wood blue. “Cutting these trees down saves the wood and lets us put the trees to good use,” the engineer says.
However, not all wood cut in Switzerland is used wisely, and some of it ends up as firewood, remarks Ernst Zürcher. One of the main reasons for this is the rise in the price of fossil fuels. A better approach would be to use wood by order of priority, with wood being devoted first and foremost to construction, then to composite products, then to paper and finally as a fuel. “In Switzerland, saw mills are closing because of lack of demand. We even export wood only to reimport it once it has been processed,” laments Zürcher. He stresses the value of promoting forests locally. “There are 5,000 people working in forests, so we are creating employment for over 50,000 people in the wood industry. Burning wood, on the other hand, creates very little added value,” he reflects. Currently, the Swiss wood industry employs 85,000 people.
Do we have enough wood? The natural growth of Switzerland’s forests produces ten million cubic metres of wood every year. The country harvests five million of those on average every year, of which 25 per cent is used for heating. The available potential is equivalent to three million cubic metres annually. There is therefore real room for improvement in how Switzerland uses its wood. And there is no shortage of projects. Sébastien Droz cites the Lignum prize, launched in 2009, as an example. “Since then, the quality, diversity and volume of projects have grown significantly,” he says. Another example is the 500-metre wooden skyway that meanders through the forest canopy in Toggenburg, near St. Gallen. This achievement is a reminder of the power of wooden constructions in Switzerland.
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