The interventions on envelopes, shown in Fig. 9, have mostly payback times lower than the useful life of the same, and the operation can also become economically advantageous for almost the 70% of the sample, considering tax deductions [13]. Thus ESCO's societies as well as public administrations can invest in refurbish- ment obtaining benefits that are also sustainable for their cost. A simple operation of inner or outer recladding with related