The construction industry could look to substitute steel for other materials to decarbonise the sector if steelmaking emissions are not reduced quickly and competitively, Kallanish learns from a report by the Energy Transitions Commission (ETC).
Its “achieving zero-carbon buildings” report says decarbonising construction requires either the decarbonising of the production of building material inputs such as cement, concrete, steel, bricks, glass, aluminium, or reducing demand for high-carbon material inputs, by using materials more efficiently or substituting lower-carbon materials.
It notes that 95% of embodied carbon emissions are from the production of material inputs, cement, concrete and steel, with the building’s structure accounting for over half of these.
Production of primary and secondary steel accounts for around 7% of global emissions, while the built environment drives around 50% of steel use by mass.
It notes achieving significant emissions reductions via supply decarbonisation will take time, with only little progress likely to be feasible over the next decade. It says this is because the cost of near-zero-emissions primary steel production will be significantly higher than conventional production for at least the next decade, and technologies are still on the cusp of reaching commercial scale.
Lengthy 20-40-year asset lifetimes imply a slow shift to low-carbon technologies, unless high carbon prices force these offline; ETC therefore highlights the importance of reducing building demand for steel.
Reducing material intensity through different building design choices and innovative construction techniques, and substituting for lower-carbon materials could in principle reduce steel demand by 15% to 2050.
Altogether, these demand efficiency strategies could in theory reduce cumulative demand for cement, concrete and steel by 30-35% by 2050.
ETC notes that alternative materials such as timber should be sustainably sourced and dealt with correctly at end-of-life in order to have a lower whole-life carbon impact, Without strict guidance, replacing concrete and steel with mass timber could become a net GHG-emitter.
It says combining the MPP pathways for decarbonisation of material production and opportunities to reduce demand for materials suggests that the total embodied carbon from the construction of new buildings to 2050 could be 65% lower. The vast majority of this reduction is achieved via the decarbonisation of material production.
Carbon pricing will be essential to drive heavy industry decarbonisation since, while decarbonisation is clearly technically possible, it will entail a green premium. MPP estimates suggest the cost today of producing zero carbon steel could be around 50% higher and while these increases will only add about 1.5-3% to the total cost of construction, developers will not voluntarily absorb these costs unless forced to do so via carbon prices or regulations.
Carrie Bone UK
