Whole-life carbon emissions and material demand in the Swedish building stock: an archetype-based stock dynamics assessment

Every building we live and work in is a story of two different kinds of energy. One is the energy we use to keep the lights on and the rooms warm, the energy that flows through the walls every single day. The other is the energy that was spent just to make the building exist in the first place. This second kind, often called embodied energy, comes from the mining of raw materials, the manufacturing of cement and steel, and the heavy machinery that lifts them into place. For decades, the focus of climate action in construction has been almost entirely on the first kind: making buildings more efficient so they burn less fuel while they stand. But as buildings become better insulated and cleaner to run, the energy hidden inside the materials themselves is becoming the bigger part of the story. In places like Sweden, where heating systems are already getting cleaner, the carbon footprint of the concrete and steel in the walls is now the dominant source of emissions.

To understand how to fix this, researchers need a way to look at the entire national building stock not as a collection of individual houses, but as a single, shifting system. They need to know exactly what materials are in the ground, how much of them are being used right now, and how those numbers will change as the population grows or shrinks. This is the challenge a team of researchers from Swedish environmental institutes and universities took on. They built a detailed digital model of the entire Swedish building sector, tracking everything from single-family homes to massive office blocks, and projected how the demand for materials and the resulting carbon emissions would evolve from today until the middle of the century. Their goal was to see if the current plans to green the construction industry were enough to meet the country's climate targets, or if something more radical was needed.

The researchers started by creating a library of "archetypes," which are essentially representative models of every type of building in Sweden. Instead of trying to measure every single house, they grouped buildings by their age, size, location, and what they are made of. For the existing buildings, they looked at how much energy they used for heating and cooling. For new buildings, they went deeper, calculating exactly how much concrete, steel, timber, and insulation goes into each square meter of floor space. They found that concrete is the heavyweight champion of the construction world. In a typical apartment building, the amount of concrete used is so vast that it outweighs all other materials combined. In single-family homes, where wood frames are common, concrete is still used twice as much by weight as the timber, mostly for the foundation and the ground floor slab. For non-residential buildings like offices and schools, steel plays a much larger role, particularly in the frames and pillars.

With this detailed picture of the present, the team ran simulations to see what the future might hold. They tested several different paths. One path was a "business as usual" scenario, where construction continues as it does today, with only slow, natural improvements in technology. The other paths were more aggressive, combining changes in how materials are made with changes in how they are used. Some scenarios focused on cleaning up the factories that produce cement and steel, using things like carbon capture technology or switching to electricity and biofuels. Others focused on using less material in the first place, designing buildings that need less concrete or swapping heavy materials for lighter, renewable ones like wood.

The results showed that while the total amount of building activity might slow down as population growth eases, the demand for concrete will remain stubbornly high unless specific actions are taken. Even in the most optimistic scenarios, concrete stays the most used material. However, the study found that the way we produce and use these materials makes a massive difference to the climate. If the industry simply continues on its current track, emissions from building construction will drop, but only slowly. But if the sector combines cleaner production methods with smarter design that uses less material, the emissions from new buildings could be cut by more than 90 percent by the year 2045.

This reduction is impressive, but the researchers discovered a crucial catch. Even if the construction side of the equation is solved, the building sector as a whole will not reach a state of zero emissions. The reason is that the emissions from the energy used to heat and cool the buildings over their entire lifespan are still significant. The study showed that while a 90% reduction in construction emissions is achievable by 2045, this does not yet lead to carbon neutrality. To get to true neutrality, the industry must attack both sides of the problem at once: making the materials cleaner and using less of them, while also ensuring the energy that runs the buildings is completely free of fossil fuels. The most effective path forward, according to their simulations, is a combination of electrifying industrial production and aggressively designing buildings to use fewer resources.

The researchers also looked at where the biggest opportunities lie. They found that the ground slabs and walls of apartment buildings are the biggest consumers of concrete, suggesting that changing how these specific parts are built could yield the biggest savings. They noted that while technology exists to make these changes, the real barrier is often how the industry works. Decisions about what to build and how to build it are often made in silos, with architects, engineers, and builders not collaborating early enough to find the most efficient solutions. The study suggests that achieving these climate goals will require a shift in culture, where the entire value chain works together to prioritize low-carbon choices from the very first sketch of a building.

Ultimately, the paper paints a clear picture of a sector on the brink of a necessary transformation. The tools to drastically reduce the carbon footprint of Swedish buildings are already available. The simulations show that a 90 percent reduction in construction emissions is technically possible. However, the study concludes that these tools alone are not enough to solve the entire climate puzzle for the building sector. Without deeper changes in consumption patterns and a simultaneous decarbonization of the energy system that powers our homes, the goal of a fully climate-neutral building stock will remain out of reach. The path forward requires not just better technology, but a coordinated effort to use less material, build smarter, and power our lives with clean energy.