Towards net-zero: success factors of tertiary building energy efficiency retrofitting projects

The decarbonisation of the building sector requires successful Building Energy Efficiency Retrofitting (BEER) projects. Success Factors are conditions or initiatives that determine project success. In the context of BEER projects possible Success Factors are Energy Efficiency Measures (EEMs) (e.g., installation of heat pumps). Despite their empirical importance, there is a relevant gap in knowledge about the Success Factors of BEER projects. In particular, it is unclear which EEM or combination of EEMs is the most successful in reducing energy consumption and carbon emissions. Addressing this knowledge gap is crucial to improve BEER projects and, therefore, to foster energy efficiency in buildings. Existing literature on Success Factors often focuses on residential buildings and energy efficiency in the industry. Such literature is focused on project management actions (e.g., project controlling and monitoring) rather than on project-related factors (e.g., the specific EEM implemented). In this article, we present and apply a novel method to identify the Success Factors of Building Energy Efficiency Retrofitting (BEER) projects, including EEMs, retrofitting date, building type and incentives. This empirical article is based on statistical and logical analyses (i.e., Fisher exact test and Qualitative Comparative Analysis) of 30 tertiary BEER projects. The results show the building envelope's thermal insulation and the installation of heat pumps as the most relevant single EEMs. However, the results highlight the implementation of combinations of EEMs as a key project's Success Factor. Particularly, findings show a recent implementation of a substantial building envelope insulation and the replacement of gas boilers with new highly efficient heat pumps as sufficient to reach substantial final energy savings in office buildings. Based on the findings, we recommend building owners and contractors prioritise these EEMs, while policymakers support their adoption, boosting BEER projects' success.