An integrated framework combining LCA and circular economy metrics evaluates bio-based retrofitting for heritage buildings. Case studies show reduced carbon emissions, improved circularity, and cost savings.
Study: Lifecycle and circular economy assessment of bio based retrofitting strategies for heritage buildings using case studies from Iran, Oman and Saudi Arabia. Image Credit: Anton Gvozdikov/Shutterstock
A paper recently published in Scientific Reports proposed an integrated framework that combined Multi-Criteria Decision Analysis (MCDA), Circular Economy (CE) evaluation, Life Cycle Assessment (LCA), and Artificial Neural Network (ANN) modeling to evaluate bio-based retrofitting approaches for heritage buildings/historical structures.
Sustainable Heritage Building Retrofitting
Climate change has imposed substantial societal costs and affected people’s lives. Studies have shown that 35% and 40% of final energy consumption and carbon dioxide emissions, respectively, are generated by the construction and building sector, which must address greenhouse gas emissions and climate change. Thus, heritage buildings with high aesthetic, historical, and cultural value must also fulfill climate and energy targets through sustainable retrofitting. This concept focuses on improving building performance while preserving cultural heritage.
An adaptive reuse strategy for existing buildings, supported by the Leadership in Energy and Environmental Design (LEED) protocol for Existing Buildings, can conserve resources and reduce carbon emissions. Adaptive reuse involves repurposing current structures while preserving their heritage character. Another key strategy for traditional building transformation is the energy transition, achieved through the incorporation of renewable energy technologies. However, heritage building renovation poses distinct challenges as it requires addressing technical constraints and preserving architectural and historical integrity.
Hence, LCA and CE methodologies are gaining attention in the discussion of building renovation. The CE facilitates a transition towards closed-loop systems from the linear “take-make-dispose” model by focusing on material recovery, reuse, long-term resilience, and adaptability. LCA complements CE by enabling a holistic environmental impact assessment across a structure's lifespan.
Recent developments in bio-based materials indicate opportunities to align retrofitting approaches with LCA and CE frameworks. These materials are derived from renewable sources such as mycelium, straw, hemp, and wood, and are suitable for circular applications due to their biodegradability, carbon sequestration capacity, and low embodied energy.
The Study
In this work, researchers introduced an integrated decision-making framework combining LCA, CE, MCDA, and ANN modeling to evaluate bio-based retrofitting strategies for heritage buildings. Three case studies, including Al-Balad District (Saudi Arabia), Bait Al Zubair (Oman), and Ganjali Khan Complex (Iran), were chosen to represent different cultural and climatic contexts.
Researchers compared retrofitting scenarios, including bio-based, traditional, and circular-optimized strategies, based on heritage compatibility, circularity score, global warming potential (GWP), and retrofit cost. Bio-based materials were chosen depending on biodegradability, low embodied carbon, and local availability.
Matrix Laboratory (MATLAB) and global databases such as the Inventory of Carbon and Energy (ICE), Ecoinvent, and One Click Life Cycle Assessment (OneClick LCA) were used to perform LCA to evaluate the embodied emissions of retrofit materials, the building’s operational energy use, and the end-of-life treatment of retrofit materials.
Additionally, researchers used the Material Circularity Indicator (MCI) model to test the circularity performance, while the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method was used for scenario ranking. ANN modeling conducted a sensitivity analysis and predicted the optimal retrofit strategy.
The objectives of the study were to compare and quantify environmental impacts between bio-based and conventional retrofitting materials across the structure’s life cycle, and to assess the potential of the bio-based retrofitting approaches to improve the sustainability and circularity of heritage buildings without adversely affecting their historical value.
At the building scale, material quantities were modeled and studied using MATLAB to evaluate net carbon performance. Simultaneously, indicators such as biodegradability, material renewability, and reusability were used to assess circularity. Using the MCDA method TOPSIS, these metrics were created within a scenario comparison framework. The proposed approach allowed a combined evaluation of economic, cultural, and environmental dimensions across traditional, circular-optimized, and bio-based retrofit options.
Significance
Researchers successfully evaluated a circular bio-based retrofitting approach for heritage buildings in Saudi Arabia, Iran, and Oman by integrating circularity assessment, ANN, TOPSIS, and LCA modeling. The results displayed that the circular-optimized retrofitting method outperformed conventional methods across economic, environmental, and cultural criteria.
Lifecycle carbon reductions of up to ~1000 kg carbon dioxide per building were realized, while circularity scores reached 0.83 in optimal scenarios. Researchers also reported annual electricity savings of $1,600–$1,900, resulting in cumulative savings of $80,000–$95,000 over 50 years. The ANN-based model demonstrated promising predictive capability, though further validation was required due to classification imbalance. Analysis indicated that environmental factors, particularly GWP, had a stronger influence on retrofit selection than cost.
In conclusion, the findings of this study confirmed that integrating CE principles and bio-based materials could improve sustainability in heritage conservation. The proposed approach offered a replicable model to bridge the gap between environmental resilience and architectural heritage. Future research must focus on dynamic energy simulation, expanded material database, social and policy integration, and real-world validation.
Journal Reference
Ilbeigi, B.M. et al. (2026) Lifecycle and circular economy assessment of bio based retrofitting strategies for heritage buildings using case studies from Iran, Oman and Saudi Arabia. Scientific Reports. DOI: 10.1038/s41598-026-47375-z, https://www.nature.com/articles/s41598-026-47375-z
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