Sustainable architecture holds research significance as a necessary approach to address climate change. However, the lack of a clear definition and diverse research methods present obstacles in this field. To overcome these challenges, this study adopts an integrated approach that combines ecological and low-carbon aspects and considers the entire life cycle system. The highlight of this article is the integration of two research methods to assess the sustainability of a building system from both ecological and carbon footprint perspectives. This approach has not been extensively explored by researchers thus far. The aim is to quantitatively explore and evaluate the sustainability performance of building systems. The research findings reveal that, among the five life cycle stages, the operational stage of a building exhibits the highest proportions of emergy consumption and carbon emissions, accounting for approximately 89.4% and 90%, respectively. From an emergy analysis perspective, newly constructed building systems demonstrate qualified sustainable parameters (Emergy Sustainability Indicator (ESI) = 2.7 > 1)). However, as the building system ages and operates over time, the overall sustainable parameters gradually decrease, eventually becoming unqualified. Furthermore, carbon emissions analysis indicates that total carbon emissions accelerate with the aging of the building, highlighting the necessity of continuous inputs of material flow, energy flow, and information flow to maintain the building system’s sustainability. The cross-feedback model emerges as the most effective correction method among the input processes, although data collection poses a challenge due to its nonlinearity. This study provides a fresh perspective for architects and building managers, offering insights that contribute to mitigating climate change and promoting sustainable practices in the built environment.