Multi-objective optimization for existing buildings retrofitting under government subsidization

The refurbishment of existing buildings allows remarkable improvements in energy performance, even by mature and off-the-shelf technologies. However, the pursuit of nearly zero energy buildings in renovation can lead to non-optimal solutions in terms of comfort. Besides, the initial cost can limit the owner in refurbishing buildings or drive the choice toward energy-efficiency measures with minimum initial cost at the expense of energy and non-energy performances. In this regard, financial incentives can be a key driver to stimulate renovation, mobilizing private investments and overcoming the high upfront costs and relatively long pay-back time of the retrofit. In the literature, the real effectiveness of incentives to improve both the comfort and the energy performance of the cost-optimal solutions has not been assessed in depth. This work investigates to which extent the incentives on different typologies of energy-efficiency measures can improve the performance of the optimal retrofits solutions. The analysis has been carried out on a set of different residential building modules, representative of different building typologies and Italian construction periods, located in two different climatic contexts representative of Italy, mixed-humid (Milano) and warm-marine (Messina) (ASHRAE 2007), optimizing the energy, costs, and indoor thermal comfort aspects.