Public Thesis Defense of Sébastien LOREAU - LAB
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Towards sustainable reuse of building services in office buildings
A framework for assessing the reuse potential of building services products, considering remedial work requirements and environmental, social, and financial performance by Sébastien LOREAU -
Friday, 5 September 2025 at 12:00 p.m. - Room AR-27 - LOCI Bruxelles - Rue Henri Wafelaerts 47-51 - 1060 Brussels
As cities increasingly embrace circular economy principles to enhance sustainability, the reuse of building products has gained prominence. Among these, building services—comprising plumbing, heating/cooling, ventilation, and electrical systems—represent significant material flows and therefore critical opportunities for intervention. However, the lack of a practical and comprehensive framework to assess the reuse potential of these systems under real-world, project-specific conditions remains a major barrier.
This thesis addresses that gap by developing a structured framework for evaluating the reuse potential of building services products. The framework facilitates the identification of required remedial actions through both visual inspection and office-based calculations, and quantifies environmental, social, and financial performance across three reuse pathways. These are benchmarked against conventional replacement or new purchase options. To operationalize this methodology, an Excel-based tool was created, verified, and validated.
The framework was applied to three case studies: reuse ex situ of an air-to-water chiller, reuse in situ of a circular air duct, and reuse in place of a recessed luminaire. Results indicated that reusing the luminaire provided notable environmental, social, and financial advantages. Conversely, chillers and air ducts showed more nuanced outcomes, with certain drawbacks depending on the reuse context. These findings confirm that reuse is not universally sustainable; rather, its effectiveness is shaped by contextual factors such as available reconditioning solutions and national environmental policies.
Four key parameters emerged as critical to reuse viability: (1) the lifespan ratio between reused and new products, (2) input power ratio, (3) lifespan of new products, and (4) local electricity mix. Input power and electricity mix had the most significant influence due to their direct impact on energy use and carbon emissions. Other influencing factors include refrigerant type, manufacturing origin, and logistical costs.
While the developed framework and tool offer a substantial advancement in reuse assessment, current limitations include partial automation, simplified uncertainty analysis, and limited impact metrics. Future work should focus on refining the tool’s scalability, data robustness, and modelling capabilities. Nonetheless, this research provides valuable decision-support for building designers, supporting more informed, sustainable, and circular design strategies.
Jury members
- Prof. Sergio Altomonte (UCLouvain) (Supervisor)
- Prof. André Stephan (University of Melbourne) (Supervisor)
- Prof. Daniel Cooper (University of Michigan) (Supervisor)
- Prof. Gérald Ledent (UCLouvain) (Chairperson)
- Prof. Geoffrey Van Moeseke (UCLouvain) (Secretary)
- Prof. Karen Allacker (KU Leuven)
- Dr Aristide Athanassiadis (EPFL)