IVL Swedish Environmental Research Institute

Climate change impact is one of the greatest ecological challenges facing our generation, and it is vital that we all bring to the table any contribution we are able to make. It has previously been assumed that the climate impact of a building’s energy consumption during operation is significantly greater than the carbon footprint of the construction phase. Until now, a rule of thumb in the construction industry in Sweden has been that approximately 15 percent of climate impact and energy consumption takes place during the construction phase, and 85 percent over operational lifetime. New building construction has proved this to be inaccurate, and a new rule of thumb ought to be that both these impacts should be judged to be of equal magnitude.

In recent years, energy consumption per square meter of living space has dropped, and an increasing proportion of this energy now comes from renewable sources. The combination of both these factors means that a building’s energy consumption has less impact on the climate than was the case previously. At the same time, we can note that the Swedish national building code stipulates mandatory provisions for energy consumption during operation, but does not regulate climate impact in the construction phase.

In 2015 a study of Blå Jungfrun, a low-energy concrete building, showed that climate impact during the construction phase was roughly equivalent to the energy use impact over 50 years of operation (Liljeström et al 2015). This project should be seen as a continuation of that study, but in this instance a newly built apartment building with frames and exterior walls of cross-laminated timber is under the microscope.

The project aims to deliver a transparent life cycle assessment of the climate impact of a newly produced apartment building with frames of cross-laminated timber (CLT). Addressing the building’s whole life cycle means including all aspects of the construction phase, including the production of materials, building transports and processes on the construction site, as well as energy use during the building’s operating life, maintenance and ultimate demolition.

Our goal is to: • Expand knowledge of the construction process and the climate impact of building materials • Evaluate the relative magnitudes of environmental impacts incurred during construction and operation • Provide an up-to-date scientific foundation for assessing the environmental impact of the construction

För en svensk version, se B2260-P.

Climate change impact is one of the greatest ecological challenges facing our generation, and it is vital that we all bring to the table any contribution we are able to make. It has previously been assumed that the climate impact of a building’s energy consumption during operation is significantly greater than the carbon footprint of the construction phase. Until now, a rule of thumb in the construction industry in Sweden has been that approximately 15 percent of climate impact and energy consumption takes place during the construction phase, and 85 percent over operational lifetime. New building construction has proved this to be inaccurate, and a new rule of thumb ought to be that both these impacts should be judged to be of equal magnitude.

In recent years, energy consumption per square meter of living space has dropped, and an increasing proportion of this energy now comes from renewable sources. The combination of both these factors means that a building’s energy consumption has less impact on the climate than was the case previously. At the same time, we can note that the Swedish national building code stipulates mandatory provisions for energy consumption during operation, but does not regulate climate impact in the construction phase.

In 2015 a study of Blå Jungfrun, a low-energy concrete building, showed that climate impact during the construction phase was roughly equivalent to the energy use impact over 50 years of operation (Liljeström et al 2015). This project should be seen as a continuation of that study, but in this instance a newly built apartment building with frames and exterior walls of cross-laminated timber is under the microscope.

The project aims to deliver a transparent life cycle assessment of the climate impact of a newly produced apartment building with frames of cross-laminated timber (CLT). Addressing the building’s whole life cycle means including all aspects of the construction phase, including the production of materials, building transports and processes on the construction site, as well as energy use during the building’s operating life, maintenance and ultimate demolition.

Our goal is to: • Expand knowledge of the construction process and the climate impact of building materials • Evaluate the relative magnitudes of environmental impacts incurred during construction and operation • Provide an up-to-date scientific foundation for assessing the environmental impact of the construction

Summary report based on a lifecycle assessment (LCA), carried out by IVL Swedish Environmental Research Institute and KTH Royal Institute of Technology and targeting an apartment building constructed almost entirely of wood. The project’s main report (IVL report No B2260) is entitled “The construction phase’s climate impact. Life cycle calculation of the climate impact and energy use of a newly produced energy-efficient residential building in concrete with wooden frames” (in Swedish).