ProWoodBuild: Promoting long-lived wood buildings for climate change mitigation and adaptation

The construction sector is going to radically change  

The building sector is responsible for nearly 40% of global CO₂ emissions, accounts for more than a third of final energy use, and half of the 100 billion tons of raw materials extracted annually. Construction and demolition waste alone accounts for almost half of the total annual wastes in the EU. As the demand for buildings increases with a growing urban population, a major shift in both mindset and practices is clearly needed to maintain a liveable planet. 

Wood construction has been proposed as a means of supporting this transition, as wood-based products store carbon and substitute functionally equivalent materials with higher emissions. The sequestered carbon stored in wood is only released back to the atmosphere when it is burned or decays, making long-lived wood buildings effective carbon stores. However, increasing the use of wood, without due regard, poses threats to the biodiversity of forests, resilience to a changing climate and the forest carbon storage and carbon sink abilities. This is true both globally and locally; in 2021, the Finnish land use sector for the first time became a source of emissions, partly because of over harvesting. 

To reduce the ever-increasing pressure on forests, we should use wood more thoughtfully and sparingly by extracting as much utility as possible from existing wood products. From a circular economy perspective, reducing the consumption of resources, by extending the lifetimes of buildings and the materials that they contain, is preferable to recycling building products after demolition, which are invariably damaged in the process. This also has clear implications for climate change mitigation, as extending building lifetimes is more beneficial than recycling the wood products they contain. 

Therefore, the aim of the ongoing study is to generate a better understanding of, and new knowledge about, the lifespan of wood buildings and to propose ways in which their longevity can be extended. This knowledge can support and promote new, durable, wood construction and help extend the carbon storage of wood-based building products. Forests play a crucial role in mitigating climate change, and we need to consider all their values and roles in decision making. The thoughtful, humble and , responsible, use of wood for long-lived, high value applications, in a materials’ cascade, can help protect these valuable resources for future generations. 

Forest take the leading role 

Forests and the Earth's capacity to withstand and adapt to changes are strongly interconnected: biodiversity, climate stabilization, and forest carbon stocks are all part of this system. The many values and roles of forests must be recognized, and forestry decisions must be made with long-term, broader benefits in mind. The material taken from forests should be used as efficiently and comprehensively as possible for high-value, long-lasting, and multiple-use applications, following cascading principles. The use of wood in construction is sensible, but the focus should be on increasing the lifespan of the existing building stock and designing new buildings to be permanent and repairable, or if designed to have a finite lifespan, then the materials should be recoverable and reusable. The most effective and ecological way to increase the carbon stock of buildings is to reduce outflow, i.e. extend building lives and the wood products that they are built from. 

One of the ways to reduce the pressure on forests and take account of carbon storage and biodiversity is through the thoughtful use of materials. It is essential to adopt a circular economy approach, embodied by the EU R9 strategy: Refuse, Rethink, Reduce, Reuse, Repair… Recycle. By extending the lifespan of buildings and materials, we can reduce the consumption of resources and increase the carbon storage capacity of the building stock in the easiest and most ecologically sound way. 

Long-lived wooden buildings have the potential to decrease the effects of climate change and adapt to it. However, it is necessary to consider various factors, such as the role of forests and materials, legislation, planning, building economics, design, maintenance, attitudes, and cultural aspects, to fully understand the longevity of wooden buildings. 

A holistic understanding of longevity and resilience 

To study the factors influencing the durability and demolition of wooden buildings, we utilise a qualitative research approach that involved desk research and interviews, and quantitative analysis of statistical data. In the qualitative phase we collect data through literature research and semi-structured interviews with relevant actors throughout the building process. The interviews are ongoing and include experts from: Forest management and politics, forest bioeconomy, legislation, building economics, wood architecture, vernacular architecture, wood construction, wood science and technology, indoor air quality, and building inspection and conservation.  

To analyse our data, we adapted a process approach that created analytical constructs from the different phases of a wood building process: Forests, Circumstances, Preparatory, Design, Construction, Maintenance and Beyond. We aim to map the factors that affect a building's longevity within these units. The approach is iterative and is based on systems thinking to ensure a comprehensive understanding. 

One of our main outputs will be a book of practical guidelines for good practice, as well as habits-to-avoid, to ensure long-lived and resilient wood building.

The project is partly funded by the Finnish Ministry of Environment under the Low Carbon Built Environment programme.