Material production accounts for close to a quarter of global greenhouse gas emissions, but receives little attention compared to energy, meat, or deforestation. In a new report for the International Resource Panel, we show that reducing the use of emissions-intensive materials such as metals and cement in buildings and cars can lead to significant emission reductions. Savings are greatest with measures that reduce the need for new production altogether. Unfortunately, current policy often supports and promotes the use of more materials.

It is natural to focus on energy use when we think of greenhouse gas emissions from buildings. In many countries, however, it is the production of building materials that is causing higher emissions than heating or cooling buildings. Scandinavia is a leader in the development of carbon-free material production with the Swedish Hybrid pilot plant using hydrogen instead of carbon to reduce iron ore to iron and the Norwegian carbon capture plans for cement production at NorCem in Brevik. It will take at least two to three decades for such advanced green technologies to transform material production, given that these have yet to be tested and commercialization remains. In the meantime, the focus should be on reduced use and increased reuse of emission-intensive materials.

In the resource panel report, we have quantified possible emission reductions through increased resource efficiency for housing and cars. We investigated policy instruments that affect resource efficiency. The results are clear. The largest emission reduction can be achieved through increased utilization of the products so that demand for new buildings and vehicles is reduced. Emission reductions are complementary to those achieved through energy efficiency and renewable energy.

In relation to housing, we find that there is a significant potential for limiting the growth in floor space and improving the utilization of homes. For example, many older people continue to live in large homes when their children move out, while young people are desperately looking for a place to start their own family. Policies should make it easy to move to housing that is appropriate for the current life-stage, rather than hindering moving by increasing the cost of shifting ownership, such as through a tax on sales or a registration fee (stamp duty).

Small is beautiful …

Flats in multifamily buildings are smaller and often better organized than single-family homes. In addition, they tend to have lower energy consumption. Multifamily buildings also provide the opportunity to share part of the infrastructure. One example are shared guest rooms, which can be reserved if needed, rather than every flat having their own guest room. Unfortunately, in some countries such as the United States, tax breaks for home ownership are designed to favour single family homes.

but large is more profitable

Failed policies are often co-responsible for large imbalances in the housing market, which lead to the over-consumption of housing by wealthy older people and a poor supply for younger and poorer population groups. Norway is a good example of that. Here, there are large and unlimited tax incentives to invest in housing, such as tax deductions for mortgage interest and a tax exemption for the value appreciation in one's own home. Hence, for those who can afford it, it pays to buy a larger home even if they do not need it. The resulting rise in house prices makes it difficult for them young to save up enough equity to get into the housing market. The tax benefits could easily be limited to the first 30 square meters per person only, and a land tax could capture the windfall profit associated with rising property values.

Elegant, light structures

Several strategies can reduce greenhouse gas emissions associated with home construction. Lighter constructions such as trusses and self-supporting arches can reduce the amount of material per area significantly. Furthermore, more material is often used than is technically necessary, as research at Cambridge has shown quite unequivocally. We can use wood or other biological materials that bind carbon instead of reinforced concrete. But it is not only that there are few incentives to reduce the use of emission-intensive materials, many rules and standards practices favour high consumption of such materials.

Low-emissions materials

Eighty-five meters high Mjøstårnet demonstrates that it is possible to build high-rise buildings from wood. Construction standards needed to be adapted to permit such a structure. The report recommends adapting regulations to promote environmentally friendly material choices and construction methods. Further, certification systems such as BREEAM and LEED are important for buildings that are built better than what is required. Such systems should be adapted to promote material efficiency.

Worldwide the greatest need to change construction practices is in China. China has surpassed England in floorspace per capita, while the rate of expansion continues to skyrocket. The building style is high-rise towers of glass and concrete, which need more material than the dense low-rise houses recommended in the Resource Panel’s Weight of Cities report. The service life of Chinese buildings has historically been extremely low, around 30 years. The hope is the quality of current construction has improved so that new buildings will be adequate for a much longer period.

Shared fleets of on average smaller vehicles

For cars, we find that strategies that reduce the number and size of cars can deliver significant reductions in emissions related to car production and operation. The sharing economy, which is based on mobile apps, can be the key to making better use of cars. On ride-sharing platforms like Same-Way or BlaBlaCar, it is possible to find passengers travelling long distances or get hitch-hike with somebody. Acquaintances living in Denmark report that there is extensive use of ride sharing also for daily journeys with established 'stops'. It even starts competing with the bus.

Perhaps a little safer in relation to infection control is car sharing, which has now also reached smaller cities, and which makes it easier to live without owning a car. You rent the car per hour when you really need it. The advantage of car sharing is that the size of cars in the car fleet decreases because you have a large car available the few times you need to shop for furniture, while you rent a small car if you are going to drive the child to the football match. Using on average smaller cars provides savings of both metal and energy.

Now that a transition to clean energy is underway, it is important to address the remaining sources of emissions. It is time for climate policy to aim at the significant potential to reduce emissions through material efficiency and the circular economy.