In recent years, global studies have attempted to understand the contribution that energy demand reduction could make to climate mitigation efforts. I will present the bottom-up, whole-system framework that we developed for the UK to estimate the potential for energy demand reduction at a country level. Replicable for other countries, our framework demonstrates that the UK can reduce energy demand of 52% by 2050 compared with 2020 levels are possible without compromising on citizens’ quality of life.