Abstract Demand-side energy reductions have so far received less policy support than supply-side net-zero technologies. Here we undertake a demand-focused process for energy scenario analysis, led by policymakers and evaluated through public dialogue. We codesign, describe and model four societal futures that aim to achieve the UK’s 2050 net-zero target. The uniquely close involvement of policymakers leading the project generates markedly different narratives that reflect policymakers’ concerns while still leading to scenarios with reductions in energy demand of 18–45%—exceeding what policies normally suggest. By 2050, technology-focused systems cost 20–100% more than lower-demand ones. While intensive cocreation requires more complex interactions compared with academic-led research, it provides space for important, and otherwise absent, energy demand conversations. This work demonstrates how engaging policymakers to colead energy scenarios can challenge conventional policy assumptions on energy demand while offering an approach to support global climate mitigation efforts.