Energy refurbishment of a University Mediterranean building: evaluation of the incentive share to achieve a cost-effective nZEB standard

To achieve the goal of decarbonization by 2050, the existing buildings, both private and public, should be renovated. Concerning public buildings, the annual renovation rate of 3% envisaged by Directive 2012/27/EU should be increased to meet the objectives set at the European level in terms of energy efficiency. The stringent targets have been confirmed by the “fit for 55” package. In this paper, a university building in Naples (South Italy, typical Mediterranean Climate) is investigated. It is brought to the standard of nearly zero energy building through different energy efficiency measures. Based on the lifespan of the individual retrofit measure, a reasonable payback period is set. Then the incentive needed to get it is evaluated. What emerges is that greater incentives are required, even up to 80%, for interventions that have a longer lifespan, i.e., the thermal insulation of the building envelope. A form of incentive equal to 40% of the investment, on the other hand, would make it possible to pay off all the interventions in about 10 years, insulation of external vertical walls and roof, replacement of transparent building envelope and installed systems, installation of a photovoltaic system. This solution would make the building a nZEB allowing a reduction of the total primary energy consumption of about 41% and a reduction of CO2 emissions of 46%.