Holistic Impact and Environmental Efficiency of Retrofitting Interventions on Buildings in the Mediterranean Area: A Directional Distance Function Approach

The study focuses on the application of a nonparametric methodology for evaluating thesustainability of retrofitting interventions to be applied on different typologies of buildings anddifferent climate zones of the Mediterranean area. The paper starts from the analysis of data collectedthrough the HAPPEN project, that is a H2020 European project which proposes a holistic approachfor a deep and sustainable renovation of the Mediterranean residential Building stock. Even if theEuropean Commission allocated considerable funds for retrofitting interventions, the choice of theoptimal solution is not always that easy because several variables have to be considered. The presentmanuscript proposes a methodology to compare different retrofitting solutions combining Life-CycleCost (i.e., LCC) estimations with the nonparametric Directional Distance Function approach (i.e.,DDF). In detail, the literature suggests that the DDF can be effectively used for comparing differentobservations through efficiency scores. The main result of the paper is the definition of a hybridmethodology that, starting from estimates of LCC and applying a DDF technique, represents asimple method for evaluating the best retrofitting intervention. Results are represented by two scoreswhere the former represents a holistic efficiency measure, while the latter shows an environmentalefficiency score.