Modeling policies for the EU building stock decarbonization at sub-national resolution

Understanding how the energy needs of the different sectors will evolve in the future is key to informing climate policy design. For the buildings sector, this involves considering heterogeneity in technological, socioeconomic and climatic conditions.  In this work, we develop a building energy sectoral model for Europe that is able to consider technology adoption dynamics at the subnational scale, with high (0.5° x 0.5°) resolution. The model focuses on energy efficiency, by considering  building renovation, space heating and space cooling, and the interplay between them. We simulate wide-scale renovation waves in Europe, understanding where we may expect more households renovation efforts, and where policy support will be most needed in the following decades. We develop three scenarios: the Reference one, where no public policy is in place, the Historical Renovation Rate one, where we reproduce the renovation trends observed in the last years in the EU countries, and the Low Energy Demand one, where a high renovation rate is achieved, along with a cap on floorspace and strong electrification of end uses. In these scenarios, although space cooling energy demand is expected to increase, most efforts target reducing space heating energy demand and electrifying end-uses.  This study implies that energy renovation investments in EU27 need to increase by roughly 16%, in respect with historical data, to significantly reduce energy demand and emissions. Spatial clustering of renovation activities, which this  work uncovers with unprecedented detail across the EU both between and within countries, should be anticipated and explicitly accounted for in the design of European-level policy instruments. To increase renovation rates through subsidies, we find that public government support should roughly match private  investments, especially in those regions where the conditions of the building stock, construction costs and energy expenditures might not motivate households to renovate. This is a significant departure from the current situation where  private investments are about 20 times higher than public ones.