**Appendix B**

To build the FIDELIO database, many di fferent data sources are used. The core of the database is the IO data, which is the main source of information that feed the production block and the trade block. The IO core is built mainly using the World Input Output Database [41] (WIOD, 2016 release). In particular, the model uses the WIOD international and national supply and use tables. Whenever the WIOD database does not provide all the necessary information, other databases, such as Eurostat supply and use tables or OECD data are used.

Besides the IO core, other databases are necessary in order to compile data for the other blocks of the model. For the household block, the main data sources come from Eurostat. The main datasets used are "non-financial transactions of households and non-profit institutions serving households" (nasa\_10\_nf\_tr), "final consumption expenditure of households by consumption purpose—COICOP 3 digit" (nama\_10\_co3\_p3), "heating degree-days by NUTS 2 regions—annual data under Energy statistics" (nrg\_esdgr\_a) and "financial balance sheets of households and non-profit institutions serving households" (nasa\_10\_f\_bs). Other datasets come from the OECD—"simplified non-financial accounts" (no. 13), "final consumption expenditure of households" (no. 5) and "financial balance sheets—consolidated" (no. 710)—and from the National Statistical Institutes of Belgium, China, Czech Republic, Hungary, India, Slovakia, Turkey and the United Kingdom. Some data on household energy consumption are taken from the EU Reference Scenario 2016 on energy, transport and GHG emissions containing trends to 2050 [42]; population demographics from United Nations projections [43]. As regards the governmen<sup>t</sup> block, the main sources come from Eurostat datasets—the main datasets used are: "non-financial transactions" (nasa\_10\_nf\_tr), "government revenue, expenditure and main aggregates" (gov\_10a\_main) and "government deficit/surplus, debt and associated data" (gov\_10dd\_edpt1)—, WIOD data, the OECD dataset on general governmen<sup>t</sup> debt—"general governmen<sup>t</sup> debt – Maastricht" (no. 750)—and data from the World Bank. The labor market is described using the WIOD social accounts, and other data from Eurostat, World Bank, and CEDEFOP. Finally, for the energy block data comes from the WIOD (2019) energy accounts (https://europa.eu/!Un47Cp), the POLES model, the Eurostat table on "air emissions accounts by NACE Rev. 2 activity" (env\_ac\_ainah\_r2), the ODYSSEE database [33], the EXIOBASE database [44] and the KLEMS database [45]. A detailed description of all the data sources and methods used to build the FIDELIO database can be found in [23].
