The nZEB concept and its requirements for residential buildings renovation in Southern Europe: The case of multi-family buildings from 1961 to 1980 in Portugal and Spain

Southern Europe has an old housing stock and the challenge, as rest of European Union Member States, to transform it into a decarbonized one, by means transforming existing buildings Nearly Zero Energy Buildings (nZEB). States have large margin discretion when defining requirements for nZEB. In this paper, nZEB renovation residential in Portugal Spain are studied detail (unlike usual more general comparative studies) specific building typology with poor energy performance. This is done checking whether building, renovated different combinations improvements envelope active systems two comparable cities each these countries, fulfills or not, comparing results CO2 emissions reductions. One considered those necessary fulfill compulsory major both countries check how much we already approaching decarbonization sector. The show that standards applied typical multi-family 1961–1980 will significantly contribute descarbonization type typology, reductions 80–96% 71–94% Spain, if they applied. However, some aspects regulations could possibly be improved such restrictive current renovations way from renewable sources ensured among others.