On the viability of nearly zero energy buildings in the Mediterranean urban contexts.

The aim of this paper is to study, evaluate and demonstrate the technical feasibility of nearly zero energy buildings (nZEBs) in the Mediterranean urban contexts. To achieve this purpose, the energy performance (EP) of selected typical residential buildings in the urban Athens area have been investigated in detail, in order to properly identify the buildings’ energy requirement in winter and summer conditions and finally propose targeted retrofitting hypothesis towards nZEBs. The study has been developed on the real case study of a social housing compound of the 1960s, with typical structures built by reinforced concrete and infill walls. The urban setting is located in the Agia Varvara suburbs, in the western Athens Metropolitan Area, which, together with central Athens, present the highest heat island intensity of the whole city. Starting from performed simulations resulting in extremely low EP at the initial state of the existing compound’s buildings, alternative retrofitting design scenarios have been studied and validated, which prove the technical feasibility of nZEBs. Further reflection on the estimated costs of proposed energy retrofitting options clearly indicates the need for additional tools and measures to be developed at public, legislative and market level to counterbalance the large payback times of energy retrofitting measures.