Abstract
The high initial investment required in existing building refurbishment can limit the initiative of the building owners and prevent the full exploitation of a huge energy saving potential. Public incentives can play an essential role in fostering the energy retrofitting of the existing buildings and in increasing the renovation rate of the building stock, effectively reducing the energy final uses, the dependence on the fossil fuels, and helping meet the national efficiency targets. Public subsidization are intended to enhance the economic performance in terms of global cost of the energy efficiency measures for the owner, in order to induce positive actions and move optimality from low to high energy efficient solution. In contrast, the overall economic efficiency is obtained with combinations of interventions, able to achieve a certain energy saving target for the entire building stock at the minimum initial Investment Costs (IC). This paper tries to identify the overall economic efficiency in reducing the energy consumption of the existing stock and compares it with the efficiency of solutions optimal from the owner’s perspective, in order to support more efficient subsidization strategies. Different mixes of three reference building archetypes, representative of the existing buildings, are considered to define different possible stocks, in order to analyse their impact on the efficiency of energy renovation solutions. Four groups of energy efficiency measures (EEMs) dealing with respectively the opaque envelope insulation, the windows substitution, the heat generating system replacement, and the mechanical ventilation introduction are defined and their combinations considered.