English: "Overview of system-level results. The x-axis shows the transgression levels for nine planetary boundaries, total CO2 equivalent emissions, the impact objective as the weighted transgression level, the total annualised system costs and the abatement or mitigation costs per ton of CO2 derived from the difference in costs and GHG emissions compared with the BAU. The y-axis shows the different scenarios, which are optimised either by least cost (Cost), impact (WTL), and, when all transgression levels < 1, for the WTL solution also by boundary-constrained least-cost (Cost + ). Scenarios have differing restrictions, which are noted after the optimisation type description; “no-col” does not allow for trade, “no-N/O” does not allow for nuclear or onshore wind, “PG” combines the two previous restrictions and “Hyd” allows only hydrogen for heating. Colour legends for the five different x-axis metrics are shown on the right." "Fig. 3 shows the transgression levels for each planetary boundary downscaled to the building heating sector of the EU27 + 1. Analysing the BAU solution, it shows an average TL of 5.2, and attains a maximum TL in the category atmospheric CO2 concentration (climate change). The HRE4 scenario is still vastly unsustainable with only marginally less transgression in climate change-related boundaries (recall that HRE4 is similar to the BAU but uses more gas instead of oil and coal)."