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Regulations concerning real estate markets have long focused on improving energy efficiency in buildings, which has led to significant reductions in their life cycle emissions since the early 2000s.

However, regulations often fail to address other factors affecting buildings’ life cycle emissions, such as the production of building materials and the construction process itself. A new study from Aalto University reveals that these account for over 70% of the climate impact of new buildings.

Researchers also highlight that land use and housing policies have a major effect on the life cycle emissions of new developments. For example, building on green areas increases emissions by 4–8% due to the loss of carbon stocks — an impact often omitted in life cycle calculations. While dense urban development can improve land-use efficiency and reduce the relative impact of building on green spaces, increased construction overall leads to greater total emissions.

‘Dense construction often relies on concrete and steel, which have high carbon footprints. In the future, the benefits of dense cities should be reinforced by focusing on low-carbon construction,’ says Seppo Junnila, Professor of real estate economics from Aalto University.

From green space to dense construction

The study analyzed the life cycle emissions of new buildings in Helsinki’s Vuosaari district and two comparable areas between 2001 and 2020. Emissions from buildings decreased by 42%, primarily due to improved energy efficiency and increased use of renewable energy. However, emissions related to construction remained unchanged—except in one of the study area where renewable natural materials were used in construction.

“Development in Vuosaari began in the 1990s when the area was largely green space. Since then, it has seen significant construction, and plans are underway to build homes for nearly 2,500 more residents by the end of this decade. This means more than six additional hectares of green space will be lost, making it a suitable subject for our study,” says Doctoral researcher Ilmari Talvitie.

Vuosaari was compared with two other Helsinki districts—Mellunkylä-Kontula and Kannelmäki-Malminkartano—that are similar in size and socioeconomic profile. Using geospatial data and life cycle assessment methods, researchers examined how different land use and construction practices impacted the carbon footprint of new buildings.

‘One interesting finding is that in Kannelmäki-Malminkartano, the city promoted low-carbon and ecologically sustainable construction, and this was reflected in the results. Construction-related emissions fell by 13%, and carbon storage in the building stock increased significantly due to the use of wood,’ Talvitie notes.

Increasing urban carbon stocks

According to the researchers, reducing construction emissions requires new ways of evaluating building emissions, as well as more ambitious land use and housing policies from municipalities.

‘Building emissions are often measured in terms of efficiency—emissions per square meter. But even if emission efficiency improves, total emissions won’t decrease if we build more. Climate-smart land use and housing policy should consider both per-capita and absolute emissions and aim to preserve existing infrastructure and green areas. This would enable more climate-resilient urban development,’ Talvitie explains.

Timber construction can also promote low-carbon building and increase municipal carbon stocks.

‘Our research shows that the carbon storage capacity of wooden buildings can even exceed the carbon stock lost due to greenfield development. Should municipalities set carbon stock targets for urban development areas? Currently, they don’t,’ Talvitie asks.

The researchers stress that in addition to regulations, market incentives and clear rules are needed to steer investment toward low-emission solutions.

‘In Denmark, for example, alongside mandatory emission limits, there’s a voluntary low-carbon certification that encourages market-driven competition in low-carbon construction. Such systems create space for frontrunners and can accelerate the sustainability transition in the construction sector by offering visibility and a competitive edge to climate-conscious actors,’ Talvitie concludes.

The study was recently published in the journal .

Contact: 

Ilmari Talvitie
Doctoral Researcher
Aalto University
+ 358 40 717 9647 
ilmari.talvitie@aalto.fi

Seppo Junnila
Professor
Aalto University
+358 50 511 5816
seppo.junnila@aalto.fi