Global warming, driven by greenhouse gas emissions, threatens to exceed the 2 °C threshold set by the United Nations Convention on Climate Change. The construction sector contributes to 37% of global emissions, divided into embodied carbon from materials and operational emissions. This study evaluates the environmental impact and energy performance of three construction assemblies for a single-family house in Coimbra, Portugal: traditional ceramic brick, aggregate concrete blocks, and wood frame. A BIM-based method integrating lifecycle stages (A1–A3, B4 and B6) was applied to analyse embodied and operational carbon. The energy simulations, conducted using LadyBug and HoneyBee in the Grasshopper environment, revealed the wood frame assembly achieved the best performance, reducing annual thermal load by nearly 2000 kWh compared to concrete assemblies. Embodied carbon emissions were significantly lower for wood frames (77 kgCO2e/m2), compared with ceramic brick (478 kgCO2e/m2) or concrete blocks (461 kgCO2e/m2), highlighting timber’s carbon sequestration benefits. Despite better operational performance, concrete options exhibited higher long-term emissions due to poor thermal efficiency. By integrating energy simulations into lifecycle analysis, designers can prioritize solutions that achieve a balance between thermal performance, occupant comfort, and environmental impact, ultimately supporting the global goal of carbon neutrality, while considering a holistic approach. While wood frame assemblies offer a sustainable alternative, broader strategies, such as integrating circular economy principles and enhancing public awareness, are vital for systemic change. Limitations, including early design-phase data and incomplete lifecycle stages, highlight the need for further research to refine sustainable building practices in Portugal and beyond.