• STEP 5-6: Selection and Assessment of Retrofit Measures
While the Guidelines discuss different retrofit alternatives, a subset of actions are to be selected finally by decision-makers. It is fundamental to guide stakeholders during the planning procedure, alerting against the possible errors and effects of each measure, through a method of selection based on several criteria. For the evaluation of the selected packages, a risk-benefit analysis is proposed.
Starting from a list of common measures for the three cases, they have been divided into three categories: interventions on the building (e.g. wall insulation, window refurbishment, tents introduction, etc.), interventions on the plants, management interventions and user involvement. For each case, the most appropriate options were selected from those listed (e.g. in case 1, given the presence of antique finishing, work on floors and walls were excluded, but interventions such as, system replacements, building automation control, curtains, etc. could be considered). But assessing each singular strategy does not make possible to evaluate the effects given by the total amount, as intended by the same Guidelines, and it dilutes also the verification times.Hence, it is preferable to combine measures in packages (e.g. in the case 3: package 1='refurbishment' includes removal operations of degradation, roof improvement to limit the problems of water infiltration present).
The assessment of measures can be made on a five-level scale, through the examination of qualitative data (risk of material and spatial impact, influence on the use, etc) or collected quantities (energy performance, comfort data, payback time, GHG emissions, etc.). A critical aspect is the lack of a measurement weighing criterion: if the assessment is compiled by a multidisciplinary team, in fact, it would be a sort of multi-criteria evaluation in which each actor considers the single choice according to his point of view. Hence, for example, a window replacement could be positive if considered from an energy expert’s point of view, but negative from a conservation one. Everything should be reviewed in relation to specific needs as well as the condition of the building, as anticipated above.
As Guidelines mentioned, “this method should not be seen as a mechanical tool that provides an answer” (page 22), but it’s meant to allow a transparent dialogue to make a decision on interventions. So, the assessment procedure represents a possible basis of work to discuss with the team and all the stakeholders the different proposals, according to criteria and objectives, established case-by-case [29].