CIRLAB: A multi-criteria assessment model for buildings, integrating circularity and lifecycle indicators

This paper introduces CIRLAB, a multi-criteria assessment model designed to integrate circularity with lifecycle environmental indicators in the early stages of building design. Unlike existing frameworks that focus on specific aspects of circularity or place less emphasis on key sustainability factors such as resource longevity, waste hierarchy prioritisation, lifecycle impacts, and multi-level integration, CIRLAB offers a comprehensive approach by combining four composite circularity indicators—Design for Adaptability, Design for Disassembly, Resource Longevity, and Circular Flows—with two lifecycle metrics— Embodied Carbon and Embodied Energy. The model features a circularity matrix based on material flow modelling, and a decision tree to handle disassembly dependencies. It applies a novel mathematical model, employing a flexible weighting system aligned with the waste hierarchy, which is adaptable to specific project contexts and applicable across building scales (material, component, system, and whole building) and layers (Structure, Skin, Space Plan, and Services). Using the PROMETHEE II and GAIA graphical tools, CIRLAB enables transparent ranking and visualisation of design alternatives. The proposed model was implemented in an Excel-based tool with automated calculations and validated through an illustrative case study involving four hypothetical design scenarios. Results highlight that relying on isolated circularity indicators does not ensure lower environmental impacts, underscoring the need for integrated evaluation. Moreover, a more inclusive assessment of circularity may yield outcomes that diverge from solutions conventionally recognised as circular. Sensitivity analysis confirms the model's reliability. CIRLAB offers a practical and reliable tool that supports informed decision-making, helping balance circularity with sustainability and guiding building design across the entire process. • Introducing CIRLAB, a multi-criteria model integrating circularity and lifecycle indicators • Integrating four new composite circularity indicators for building assessment • Uses PROMETHEE II and GAIA to rank and visualise design alternatives • Aligns indicator weighting with the waste hierarchy across building levels • Validated through an illustrative case study comparing four early-stage design scenarios