Towards a Sustainable Future: The Importance of Wood in Construction

Wood has always been a traditional building material in Finland. It has been readily available and it is easy to work on. As an insulating material, wood has been excellent in cold winters to keep the heat in and the cold out. Most commonly, traditional buildings are made of logs, with a variety of corner joint techniques and decorations. The trees used for log houses were carefully selected and felled in the spring while the tree was dormant. Log houses were also designed so that they could be dismantled and rebuilt one log at a time if necessary. The surface was usually protected with red ochre and the roofing material chosen was shingle.

When we think of a timber house, almost all of us conjure up an image of a 40–50s veteran houses with a porch and central wall. The standardised houses were designed by Alvar Aalto, Aarne Ervi, Aulis Blomstedt and other important architects of the time. Here, too, the building material was wood, albeit with modern frame construction and sawdust insulation. Felt, sheet metal or other more modern materials were chosen as the roofing material.

From old traditions, we have developed a certain relationship with wooden houses. For many, a wooden house reminds them of their childhood and grandma’s house, for others of rotting logs and burnt chimneyless huts or the mouldy air of a summer cottage. For many builders, a wooden house means a perpetual maintenance issue and a risk of moisture in the structure. ‘Wood is only good for the fireplace and the parquet!’ was still a popular mindset among developers in 2020. There is still a perception of the stone house as a house of value and the wooden house as somehow of lower quality. Naturally, this is not true. Many of the prefabricated concrete buildings of the 60s and 70s are coming to the end of their life cycle. These buildings were once advertised as maintenance-free. The saying ‘maintenance-free is the same as beyond repair’ seems to ring true. Of course, a traditionally built solid brick house is a very good structure, as is a log house. But it is not about the material – it is about good construction.

The new advent of timber construction has been talked about for as long as the advent of the information model, i.e. at least 25 years. Well, information modelling is finally a reality – and so will be timber construction. Why? Because wood has excellent properties that the world and Finland need today. Sustainability, carbon neutrality, the circular economy, and energy saving are growing phenomena, and their importance in relation to the economy is increasing. Helsinki has launched its ‘Carbon-Neutral Helsinki 2035’ programme and Vantaa has a similar programme for 2030. The government will likely start regulating the carbon footprint of buildings as early as 2025, requiring developers to indicate their projects’ carbon footprint in the building permit, as is currently the case for the energy class.

Big cities face a big challenge; how to make energy production carbon neutral? Much of a city’s energy is produced for district heating and is largely generated from fossil fuels. Buildings need to become self-producing units and transfer surplus energy to the grid or to storage. At the same time, the energy consumption of buildings must be reduced even further. As the energy efficiency of buildings has improved dramatically in recent decades due to new regulations and technologies, attention now turns to energy and carbon during construction. The energy consumption during the construction of modern buildings is estimated to be about one fifth of the consumption during the whole lifetime of the building.

Another major challenge is material efficiency and its carbon footprint. In this respect, wood is superior to materials such as concrete. VTT Technical Research Centre of Finland has discovered that the carbon footprint of a wooden house is about half that of a comparable concrete building (VTT 2017). Wood sequesters carbon in the building structure and the rule of thumb is that a tonne of wood sequesters about a tonne of carbon. Carbon is sequestered in the building structure and façade for 100–200 years. Similarly, the production of cement, which is used as a binder for concrete, produces 5–8% of global greenhouse gas emissions. Not to mention the fact that we are running out of the sand used in concrete. Concrete is an excellent material and cannot be completely replaced, but the increasing use of wood is better for the environment. There are still no fully accurate metrics to calculate these due to the many variables involved, but it is safe to say that wood is a sustainable and environmentally friendly choice.

The third important factor is recyclability. As with log houses in the past, modern timber buildings can be easily dismantled, recycled and reused to some extent. The recyclability of concrete is poor.

Other benefits of wood include the domesticity and local sourcing of the material. The use of wood employs Finnish workers and companies. Extensive use of wood in construction can add an estimated EUR 1 billion to the total output of the national economy (PTT 2012). Wood is also a lightweight material, its impact on building foundations is significant, and it is often possible to raise the height of existing buildings using wood. The importance of using wood in interior surfaces should also be mentioned. On average, people find wooden surfaces more pleasant and healthier than artificial materials.

Arco is investing in the development of wood construction together with other actors in the sector. The use of wooden structures and façades still requires further research and clarification of regulatory requirements. In collaboration with leading specialist designers, fire consultants, product component manufacturers and authorities, we are developing wood construction towards a more versatile and everyday use. An example of this development is Keilaniemen Portti, built by Varma, which will be the tallest wooden office building in the world when completed. There are also a few other wood building projects on the drawing board.

As stated in the VTT study mentioned above, timber construction is an ecological act. The same article also took a strong stance on design:

‘The architect is very much a watchdog, because they have the power to decide whether a building will be carbon efficient.’

Sami Horto
Architect SAFA