From demand to action: Analysing building emissions and refurbishment scenarios towards climate neutrality

Germany is endeavouring to reduce its greenhouse gas emissions and become climate-neutral by 2045. There are various approaches and measures to achieve this in different sectors. After the energy sector, industry and transport, the building sector in Germany, with 111.7 million tonnes of CO 2 equivalents emitted in 2022, is a major emitter that offers a high potential for reducing emissions - especially space heating, which accounts for 73 % of carbon dioxide emissions in the residential sector (as of 2020). To decarbonize space heating in residential buildings, the heat supply has to be fully decarbonized. In addition, taking action on the demand side, e.g. heat demand reduction through increased buildings efficiency, will help to reduce efforts on the supply side. Depending on the buildings age and its heat demand, different actions for insulating the building can be realised. In a case study for a German city, various refurbishment steps are analysed to determine the specific costs of the refurbishment and the economically viable reduction in heat demand. Building upon these initial steps, we assess the interconnections and dependencies stemming from actions on the supply side. The outcomes signify the optimal cost configuration for the combination of both activities. The results of the issues analysed also show their impact on building emissions in a reasonable period up to the planned climate neutrality. • The study evaluates various refurbishment measures' effects on heat demand and emissions in the urban building stock. • Findings indicate that roofs have a limited impact on heat demand, while floors are more critical due to higher U-values. • A sensitivity analysis shows how different voluntary refurbishment rates impact on heating demand. • I Comparison of insulation thicknesses (16, 20, 40 cm) shows increased facade insulation does not significantly reduce heat demand. • Refurbishing the building envelope alone is insufficient; combining with heating upgrades is key for emission reductions.