 Portugal has set a goal of becoming carbon neutral by 2050, which requires significant decarbonization efforts in the building sector. In order to achieve this goal, policymakers need to understand the primary drivers and barriers of energy efficiency measures. This paper reviews existing policies and actions in Portugal and assesses their effectiveness in improving energy efficiency and reducing carbon dioxide emissions in the building sector. The study found that electrifying heating and cooling, implementing energy efficiency measures, and increasing the use of renewable energy sources are all necessary for achieving climate neutrality. Additionally, the study suggests that alternative energy plans could be implemented to reduce investment costs and increase greenhouse gas reductions. One such alternative plan, alternative four, was found to have the greatest potential for cost savings and emissions reductions. This article was authored by Sara Capello, Thiago Sores, Isabel Azavito, and others.