Air conditioning and the future electricity system in Great Britain.

Climate change is driving hotter summers in temperate regions including the United Kingdom, where historically air-conditioning demand has been low and energy-system planning focused on winter peaks. As Great Britain's energy system moves toward renewables-dominated supply, understanding how emerging cooling demand could interact with system adequacy becomes increasingly important. Here, we use a risk-opportunity analysis framework to examine how cooling uptake could affect future planning and adequacy of the electricity system, integrating international ownership data, qualitative analysis of policy, and first principles system-capacity calculations. We aim to identify where cooling creates underexplored risks or opportunities, and what assumptions need revision. We find current official scenario assumptions for residential air conditioning uptake are too narrow, and present ownership is potentially an order of magnitude higher; therefore, the system-level implications of more rapid cooling uptake remain essentially unexplored. While there may be a noon surplus of solar energy in summer, official scenario analysis does not yet examine peak loads in summer and may therefore miss interactions with low-wind periods and declining afternoon solar power, potentially underestimating requirements for storage and flexibility. We recommend summer adequacy analysis be included in planning. Underestimated cooling demand could lead to missed decarbonisation targets or greater operational challenges, but treating low demand assumptions as constraints could lead to missed policy opportunities to protect health from overheating and to make use of reversible heat pumps. Air conditioning needs to be understood within a systemic context of electrification of heating, expansion of renewable energy, and adaptation to higher temperatures.