How user behaviour affects emissions and costs in residential energy systems—The impacts of clothing and thermal comfort

To mitigate climate change, energy systems must be decarbonised. Human behaviour affects energy systems on residential scales through technology adoption and use, but is often neglected in models for analysing energy systems. We therefore study the optimal planning and operation of a sector-coupled residential energy system driven by economic and environmental interests and user behaviour in terms of desired thermal comfort and clothing. Methodologically, we combine a highly flexible energy system optimisation framework for investment and operational planning, a thermal building representation, a continuous and empirically founded objective for thermal comfort as the sole driver of heating demand and an analytical multi-objective optimisation method in one sector-coupled model. We find that optimal investment in and operation of technology are highly dependent on users’ clothing and the desired comfort level. Changing from unadapted to warm clothing in transition and winter season can reduce costs by 25%, carbon emissions by 48%, gas consumption by 84%, heat demand by 20% or necessary PV installations by 28% without lowering thermal comfort. Similar reduction potentials are offered by lowering thermal comfort without changing clothing. We find that heat pumps, rooftop solar PV, batteries and generously sized water tanks are essential technologies that should be adopted regardless of user behaviour, while hydrogen is not. Full decarbonisation would require additional measures like refurbishments or further carbon-free energy sources. We conclude that in striving for decarbonisation and independency of gas, appropriate clothing and sector coupling should be promoted by policy makers and utilised by end-users as very efficient ways of reducing costs, carbon emissions, energy use and gas dependency.