IEQ and energy improvement of existing buildings by prefabricated facade additions: the case of a student house in Athens

The aim of this paper is to evaluate and illustrate the energy saving potential and Indoor Environmental Quality (IEQ) performances of a façade addition on existing and low energy performing buildings. Different technical solutions are proposed and all IEQ indicators' simulation results are presented for the case of a students' building block of the 80's located in Athens. The building is the demonstrator of the "Pro-GET-onE" Horizon 2020 project, that aims to demonstrate the attractiveness and the energy efficiency of a renovation strategy based on new façade additions combining inteGrated Efficient Technologies (GETs). The research project proposes the highest transformation of the existing building's shell with external added volumes, which generate energy efficient buffer zones and at the same time increase the building's volume (with balconies, sunspaces and extra rooms). This strategy gives also the possibility to increase IEQ performance, in different ways depending on the architectural solutions, the selected materials and the adopted technological solutions. As a general statement, the facade addition solution leads to an increase of the thermo-hygrometric conditions (both for the cold winter season and the summer period), of the facade sound insulation and consequently the acoustic comfort, and of the indoor air quality. The lighting and the visual comfort are a critical point due to the enlargement of the existing surface of the rooms: specific light enhancement techniques have been studied to optimize indoor light, therefore minimizing the drawbacks of façade expansions, and will be suggested for the final design of the case study. The detailed analysis of individual units (additions) led to the formulation of hypotheses for targeted energy retrofitting interventions in different options; with different scenarios of integrated RES technologies, these options have been analysed both separately and in combination, to assess the technical, the energy feasibility and the IEQ performance in each scenario. (paper)