The new scientific article published by the RenOnBill partner UNIGE on the journal Energy, Financial and energy performance analysis of efficiency measures in residential buildings. A probabilistic approach, presents a methodology to effectively address the evaluation of building energy retrofitting projects in a highly uncertain context. By using the Monte Carlo approach, the proposed method can address the influence of more than thirty important parameters on the final result in terms of energy savings, Net Present Value and other indices aimed to quantify the level of risk associated to complex energy efficiency interventions. The methodology is then tested on a case study related to a building built in the ‘60s and located in Rome, Italy.