The term co-benefit aims to capture a reality that is often overlooked, highlighting how investments in energy efficiency can provide many and different advantages to different subjects involved in the project. The most recent focus has been on the incorporation of co-benefits (co-impact) into decision-making frameworks to take into consideration the full range of stakeholders involved in energy investments (Ürge-Vorsatz et al. 2014). In this field of application, the commonly used approaches refer to the Life Cycle Assessment (LCA), the Life Cycle Cost (LCC), the Cost-Benefit Analysis (CBA) and the Multi-Criteria Decision Analysis (MCDA) (Strantzali and Aravossis 2016). These evaluation methods allow to evaluate a project from different points of view considering the different externalities generated. In the international literature, the criteria considered to examine energy investments are mainly divided into four families that evaluate the technical, economic, environmental and social factors of the project (Wang et al. 2009). But it is difficult to describe a project from all points of view, given that current literature is unable to provide a comprehensive response to the quantification of these impacts (Becchio et al. 2018; Bisello and Vettorato 2018; Dell’Anna et al. 2020). Theoretically, each of the co-benefits can be estimated. To do this, the impact of the policy or initiative is first quantified in physical units (e.g. tons of pollutants avoided, years of life saved, number of additional full-time jobs created, etc.) before transformation in a monetary value. A critical point of this analysis is that not all co-benefits can be assessed directly in monetary terms as if they were consumer goods. Therefore, it is necessary to apply non-market techniques to estimate them. These techniques investigate consumer preferences from individual purchasing habits (revealed preferences) or by asking them directly for their preferences (stated preferences).

Our studies clearly trace the path followed in this area of research. A line of research is represented by publications concerning the economic-financial evaluation of energy investments. This category includes publications based on the application of stated and revealed preferences methods, to study consumer behaviour towards energy investments (Becchio et al. 2019; Bottero et al. 2020; Bottero et al. 2019). Another line concerns the application of techniques to support the decision to guide the energy transition processes at the district level (Becchio et al. 2018; Becchio et al. 2017).

Most of the research has been developed in collaboration with the Energy Center Lab of the Politecnico di Torino (Becchio et al. 2020, Borchiellini et al. 2017). With reference to the most significant publications “Decision making for sustainable urban energy planning: an integrated evaluation framework of alternative solutions for a NZED (Net Zero-Energy District) in Turin” proposes an evaluation method developed by the Cost-Benefit Analysis in order to include socio-economic benefits -environmental generated by the project (Becchio et al. 2018). An energy and economic approach is applied to a real case concerning the energy requalification of a district in Turin. “Of comfort and cost: Examining indoor comfort conditions and guests’ valuations in Italian hotel rooms” estimates the willingness of consumers to pay for excellent comfort conditions in hotel rooms using the contingent evaluation method (Buso et al. 2017).