Switching to wood as a building construction material would significantly lessen the carbon footprint of building construction, according to a study conducted by Aalto University and the Finnish Environment Institute. Currently, buildings account for one-third of global greenhouse gas emissions, about ten times more than air traffic worldwide.

Researchers showed that by constructing 80% of new residential buildings in Europe with wood and using wood in the structures, cladding, surfaces and furnishings of houses, the buildings together would store 55 million tons of carbon dioxide a year, the equivalent of about 47% of the annual emissions of Europe's cement industry.

The Aikalava pavillion was built to celebrate Finland's 100th birthday. Source: Vesa Loikas

The study drew from 50 case studies and extensively analyzed the literature. Buildings were divided into three groups determined by how much wood they contain and, subsequently, how much carbon dioxide they store.

Capacity for carbon storage was based on the number and volume of wood used as building components — beams, columns, walls and finishing, for example — rather than the type of building or wood. The buildings with the least amount of wood stored 100 kg of carbon dioxide per square meter (CO2 kg m2). The next group stored 200 kg. The group with the largest amount of wood stored 300 kg per square meter.

The researchers also modeled the pace that would be necessary for such a change to achieve the level of 55 million tons per year by 2040. With 10% of new residential buildings made of wood, each storing 100 CO2 kg m2, the number of wood-built buildings would need to increase steadily to 80% by 2040, plus more wooden buildings would need to be in the 200 CO2 kg m2-storage group and over time, in the 300 CO2 kg m2-storage group.

Energy efficiency has often been the measure of the environmental impact of buildings. This requires insulation, recovery of heat and more efficient windows. As renewable sources of energy in housing increase, the construction phase takes on a larger share of a building's total environmental impact.

Ali Amiri, who is completing his doctorate at Aalto University, explained that green building certifications such as LEED and BREEAM focus heavily on the energy consumed during use, but could do better acknowledging the climate benefits of wood construction.

The study found that a 100 m2 wooden building can potentially store 10 to 30 tons of carbon dioxide. Thirty tons is equivalent to the carbon dioxide emissions of an average motorist over 10 years.

"Wood construction is sustainable only if the wood comes from forests that are grown in a sustainable manner. Shifting from short-lived products, like paper, to products with a long life-cycle, like wooden construction materials, would help minimise the impact on European forests and the crucial carbon sinks they hold," said postdoctoral researcher Juudit Ottelin.