Digital twin reveals where buildings emit the most carbon

Using an office building in northern China as a case study, the results show that operational emissions—especially from heating—dominate total emissions, highlighting how early design and technology choices can substantially reduce long-term building carbon footprints.

Buildings worldwide account for about one-third of total energy use and carbon dioxide emissions, driven mainly by heating, cooling, and material production. In China, construction-related emissions have more than doubled since the mid-2000s, placing the sector at the center of national decarbonization efforts. Across a building’s life cycle, emissions stem from material production and transport, construction, operation and maintenance, and demolition. However, comprehensively quantifying emissions across all stages and linking them to design decisions remains challenging. BIM addresses this gap by integrating geometric, material, and operational data, enabling carbon assessment to be embedded directly into the building design process.

A study (DOI:10.48130/een-0025-0014) published in Energy & Environment Nexus on 31 December 2025 by Yujing Yang’s team, Shanxi University, provides a comprehensive, design-stage methodology for accurately identifying and prioritizing carbon emission reduction strategies across the entire building life cycle by integrating BIM with life cycle assessment.

Using an integrated Carbon Emission Estimation for Buildings (CEEB) framework based on BIM and life cycle assessment principles, this study first quantified carbon emissions across material production and transportation, construction operation, alternative heating scenarios, and the full building life cycle by applying standardized calculation equations and scenario-based sensitivity analyses. To ensure data reliability and computational feasibility, the assessment focused on major construction materials—concrete, steel reinforcement, cement, sand, and masonry blocks—and simulated operational energy use for heating, cooling, lighting, and hot water under local climatic conditions. The results show that during material production, steel was the dominant carbon source, emitting 270.87 tCO₂ eq and accounting for 46% of production-related emissions, followed by concrete (29%) and cement (21%), indicating that emission reduction in material manufacturing should prioritize steel and cement-intensive processes. In contrast, transportation emissions were disproportionately driven by sand, which contributed 40% of transport-related emissions despite its negligible production footprint, highlighting logistics as a critical mitigation leverage point. Sensitivity analysis further demonstrated that shortening transport distances and switching to lower-emission vehicles could reduce total material transport emissions by up to 73.9%. For the operational phase, BIM-based energy simulations revealed that coal-based heating dominated emissions, with bituminous coal alone accounting for nearly 45% of operational emissions and heating-related activities responsible for almost two-thirds of total operational carbon output. Comparative scenario analysis showed that replacing coal-fired heating with ground-source heat pumps could cut heating emissions by over 50% and reduce total life-cycle emissions by nearly 19%, outperforming natural gas and air-source heat pump alternatives in cold regions. Finally, life cycle integration confirmed that operation and maintenance overwhelmingly dominated total emissions (94.62%), while material production and transportation contributed about 9%, and construction and demolition were negligible. Together, these results demonstrate that carbon mitigation in buildings should prioritize operational energy systems, low-carbon heating technologies, material efficiency, and localized supply chains to achieve meaningful life-cycle emission reductions.

The findings underscore that meaningful emission reductions in buildings depend far more on operational energy systems than on construction activities alone. By integrating carbon estimation into BIM at the design stage, architects and engineers can compare materials, heating technologies, and supply chains before construction begins. This enables targeted strategies such as adopting renewable-based heating, improving building envelope insulation, using low-carbon materials, and sourcing materials locally to minimize transport emissions.

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References

DOI

10.48130/een-0025-0014

Original Source URL

https://doi.org/10.48130/een-0025-0014

Funding information

This research was supported by the China Scholarship Council (CSC) (Grant No. 202308140128), and the Fundamental Research Program of Shanxi Province (Grant No. 202203021212486).

About Energy & Environment Nexus

Energy & Environment Nexus is a multidisciplinary journal for communicating advances in the science, technology and engineering of energy, environment and their Nexus.