Significant efforts are underway across all sectors of the economy to reduce greenhouse gas emissions and achieve net-zero carbon emissions by 2050. The expansion of lower-carbon energy sources has been reshaping the electricity grid generation mix, influencing the entire supply chain. Operational carbon emissions can potentially reach zero in the building sector through cleaner energy grids and on-site zero-carbon energy generation. Consequently, embodied carbon in the building life cycle could become increasingly significant in whole-life carbon. The selection of construction materials, the efficiency of construction and operational processes, and end-of-life strategies are therefore crucial to minimizing life-cycle carbon impacts. However, the broader environmental implications of this energy transition remain uncertain. This paper studies energy efficiency measures in buildings in a decarbonized grid mix, applying a dynamic LCA to a residential building in Florida, USA, evaluating and comparing the carbon emissions for an actual scenario, in which none of the environmental strategies is applied, with a scenario with envelope improvements, PV panels, and a decarbonized grid mix. The method is organized into 4 stages: case study definition, environmental evaluation through LCA, energy simulation and dynamic grid mix, and discussion and recommendations. The findings highlight the need for the built environment sector to adopt forward-looking design strategies and flexible assessment tools that can explore these dynamic changes. In doing so, the research provides insights for both practitioners and policymakers on how to align material choices, design practices, and assessment frameworks with the broader decarbonization pathways required to achieve global net-zero goals.