In the evolving sustainable transition of the construction sector, the decarbonization of buildings has emerged as a salient focal point. Notwithstanding the urgency of these directives, a notable lack of consensus among professionals and policy makers remains regarding the methodologies to apply to achieve these benchmarks and standardized metrics for results validation. In this study, we undertake a detailed exploration of sport infrastructure within the Catalonia region, in Spain, a category known for its substantial energy footprint within the European context. The investigation initiates with an overarching review of the European Union’s policy trajectory concerning energy retrofitting and decarbonization, followed by a profound assessment of the current decarbonization status of sports infrastructures in Catalonia. The research introduces a proposal for a Life Cycle strategy for Sports Buildings Retrofits, proposing a methodology that could be implemented in the current version of Building Renovation Passport proposed by the EU commission with the integration of dynamic energy simulations, life cycle analysis and life cycle cost analysis. The study culminates in a juxtaposition of environmental and economic calculations of diverse energy retrofit measures. This fact introduces a financial dimension to carbon dioxide emissions, thereby enabling the evaluation of retrofit avenues. The evaluation extends beyond conventional return on investment paradigms, introducing the economic repercussions of CO2 mitigation. The contribution of this research is to support the development of building renovation passports, consistent with the EU proposal. This document guides building owners and assists public administrations in implementing a decarbonization strategy for sports buildings in Catalonia.