Pathways toward a carbon-neutral Swiss residential building stock

Current policies to reduce energy consumption and CO2 emissions associated with buildings focus on technological developments such as energy efficiency, renovation rates and renewable energies. While technological developments are effective at mitigating climate change, the omission of lifestyle changes such as lower floor area per capita and indoor temperatures as well as disruptive measures (e.g. replacement of highly energy-consuming buildings) leave untapped potential for further savings. A dynamic stock-driven model is presented that quantifies direct energy consumption and direct CO2 emissions associated with the use phase of Swiss residential buildings. Eleven scenarios involving technological developments, lifestyle changes and disruptive measures are evaluated against relevant goals (Paris Agreement, Energy Strategy 2050 and 2000-Watt Society). Disruptive measures are modelled with a new combined lifetime-leaching approach. The scenario analysis indicates that the main leverage points for energy savings reside in lifestyle changes, whereas emission reductions can be highly levered by technological developments. Reaching all the goals is possible, but requires ambitious strategies. This study provides a basis for expanding the portfolio of climate change mitigation strategies for the residential building sector, although further research is needed to understand social, cultural and economic aspects, and indirect (embodied) emissions. Policy relevance Switzerland currently applies two policies in the building sector to reach the climate goals (Energy Strategy 2050, Paris Agreement and 2000-Watt Society). This study shows: (1) current policies (a CO2 levy on fossil fuels for heating and the Buildings Program subsidising renewable energies and energy-efficient renovations) are effective at lowering energy consumption and CO2 emissions, but insufficient to meet any of the goals; (2) reaching the Energy Strategy 2050 and Paris Agreement requires an extension of current policies and a complete phase-out of fossil fuels by 2050; and (3) achieving the 2000-Watt Society requires the measures described above, households heating only areas inside dwellings up to 20°C, and one of these three measures: (a) households living with 41 instead of 47 m2/cap, (b) increasing the renovation rate from 1.3% to 3.0%, and (c) replacing buildings consuming > 140 kWh/m2/yr. Further evaluations including social, cultural and economic aspects, and indirect energy consumption and embodied emissions are needed.