The energy efficiency concerns on the residential building stock have increased in the last years. This can be interpreted as a policy-driven phenomenon, as witnessed by the growing number of policy instruments aimed at reducing the energy consumption of buildings. However, it can also be understood as a market-driven phenomenon, as witnessed by the widespread of Voluntary Sustainable Certification Systems (VSCSs) for buildings. Despite policies being traditionally considered the most suitable tool for dealing with environmental issues, the potential of VSCSs to contribute to enhance the energy efficiency of the building sector is widely recognized. Indeed, public agencies are beginning to adopt VSCSs as performance specification requirements. Nevertheless, part of the literature has underlined that the assessment of green projects might be more effective if performed before the conceptualization of the design; this doesn’t entirely fit traditional VSCSs, precluding their role as complete contributions to the exploitation of the energy-saving potential of building refurbishments.

The research therefore focuses on the development of a decision support tool for the assessment and comparison of energy-efficient refurbishment alternatives on a pre-design stage. The tool is developed taking into account three key conditions: (1) it must be suitable to be used during the early stages of the decision-making; (2) it must take into account the EU policy on building energy performances; and (3) the tool should inform the main stakeholders on the refurbishment features that can be perceived as a risk. 

The tool includes six financial and energy-related criteria, which range from the energy performance improvement, to the property market value after the refurbishment. Criteria are selected assuming the incipient level of design detail in the early stage of the decision-making process. The performance values achieved by the refurbishment alternatives on each criterion are normalized on a 1 to 10 scale and further on represented with radar charts. The tool has been tested through applying it to case studies. The outcomes highlight that the tool can be used either for assessing alternatives concerning a single building, or to compare retrofit options for different buildings. Moreover, the tool seems able to overcome two barriers that hinder the diffusion of energy-efficient refurbishments, namely the multi-stakeholders barrier and the information gap.