Quantified scenarios show high uncertainty for UK residential space heating to 2050. There is a high risk of gas lock in without policy intervention. Some electrification of heating is very likely to be needed to meet climate policy goals. High electrification raises challenges including peak winter electricity demand. More diverse strategies including energy efficiency and biofuels have lower risks. a b s t r a c tFossil fuels are the main source of space heating in the UK, and therefore climate mitigation implies a systemic change in space heating systems. The challenge is difficult because of an inefficient building stock and high penetration of natural gas. We present new quantified scenarios for residential energy use in the UK to 2050. With minimal policy intervention the UK will remain locked into a gas based heating system, which would conflict with the policy goal of decarbonisation. However, there is a range of scenarios in which this is avoided. A system heavily reliant on heat pumps powered by low carbon electricity is UK policy makers' currently preferred alternative. We conclude that some shift in this direction is likely to be required, but complete reliance on this solution raises a number of problems. Greater use of energy efficiency and biomass can also play a significant role. These options have different risks, but a more diversified strategy would be more prudent. We conclude that the future of UK residential space heating is very uncertain, but meeting low carbon heating goals is better conceptualised as reducing reliance on gas rather than necessarily mass electrification. Our analysis has implications for any country with high use of fossil fuels in space heating and ambitious decarbonisation goals.

Electrifying the energy system and powering it by low carbon electricity is one of the key decarbonisation pathways of the energy system. This study examines annual electricity and gas consumption in a high electrification scenario in Great Britain (GB) and the implications for electricity generation and transmission infrastructure using a suite of soft-linked models. High electrification of heating and transport services, which are two major fossil fuel consumers in GB, increases annual electricity consumption and peak electricity load by 35% and 93%, respectively, by 2050 while reducing overall annual energy consumption compared to a reference case. Meeting this high electricity consumption with a supply strategy that is dependent on offshore wind could more than double the supply-side investments required compared to a reference case, if demand-side measures are not available. High electrification would also impact existing gas and oil energy infrastructure by reducing consumption of these fuels. It was found that uncertainties in socio-economic growth can amplify these implications and therefore need serious consideration by analysts and policymakers involved in designing energy transition strategies. A case study and discussion demonstrate that smart-grid aided demand-side management has the potential to minimise electricity peak load and infrastructure requirements from high electrification.