What is the embodied CO ₂ cost of getting building design wrong?

Today, carbon and cost-efficient construction are well matched. However, in the future, as steel production is increasingly done from recycled scrap in electric arc furnaces (EAFs) and concrete mix design is improved, the current balance of CO_{[Formula: see text]} impacts and costs can be altered. When this happens, structural designers need to update their design strategies, and incentives must be put in place to retain the alignment between environmental impact and cost. Here, I assess the potential of carbon taxation to improve the structural design. I also assess the discrepancy in embodied carbon outcomes if construction costs remain constant, but the embodied carbon of materials is varied. Finally, I look at the effect of an early-stage design tool, PANDA, on embodied carbon outcomes of real projects. I find that carbon taxes need to be extremely high to have an effect, and that this effect is limited to certain types of frames. Embodied carbon in construction can become disconnected from costs if the embodied carbon of materials varies heterogeneously. Finally, novel design tools can help designers substantially improve the embodied carbon of their design. This happens despite the absence of a significant monetary incentive to that effect.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.