*Econstruction steel*,<sup>2040</sup>(ktCO2e) =

$$\begin{aligned} 414 \ (\text{kt}) &\ast \left( \left( 0 + 6.4 \frac{\text{GWh}}{\text{kt}} \right) \ast \left( 0.34 \left( \% \right) \ast 0.37 \left( \frac{\text{kC} \text{CO}\_2 \text{s}}{\text{GWh}} \right) + 0.02 \left( \% \right) \ast 0.228 \left( \frac{\text{kC} \text{CO}\_2 \text{s}}{\text{GWh}} \right) \right. \\ &+ 0.17 \left( \% \right) \ast 0.248 \left( \frac{\text{kC} \text{CO}\_2 \text{s}}{\text{GWh}} \right) \ast \left( 1 - 0.30 \right) + 6.4 \left( \frac{\text{GWh}}{\text{kC}} \right) \ast 0.17 \left( \% \right) \ast 0.115 \left( \frac{\text{kC} \text{CO}\_2 \text{s}}{\text{GWh}} \right) \right) = 372 \text{ kC} \text{CO} \text{2} \text{s}. \end{aligned}$$

where the energy intensity factor and energy source shares are taken from Table 1 with the coal share reduced by 30%, and the emissions intensity factors are taken from Table A2 in Appendix A for the thermal energy sources and Table A3 in Appendix A for electricity.

For material transport and construction process, construction activities *tc*, the emissions in each timestep *t* is calculated as:

$$E\_{tc,t} = Q\_{tc,t} \* \sum\_{s} (q\_{tc,s,t} \* Ef\_{s,t})\_{\prime} \tag{17}$$

where *Etc*,*<sup>t</sup>* is the emissions for construction stage *tc* in time step t, *Qtc*,*<sup>t</sup>* is the energy for lifecycle stage *tc* in timestep *t*; *qtc*,*s*,*<sup>t</sup>* is the energy share for construction stage *tc* of energy source *s* in timestep *t*; *E fs*,*<sup>t</sup>* is the emissions factor for energy source *s* in timestep *t*.

**Figure 4.** Schematic illustration of the calculation of emissions and energy demand per energy source for steel production. Boxes linked with an encircled x are multiplied, a box linked via an encircled minus sign is subtracted, and boxes linked with an encircled plus sign are added up. Boxes with thick outlines are metrics that are adaptable over time in the pathways depending on the abatement measures applied, while boxes with cursive texts are input data provided in Table A1, Table A2, and Table A3 in Appendix A. The initial material demand figure is only adaptable in the sensitivity analysis. Blue boxes are result figures.
