The reuse of building systems (plumbing, mechanical, and electrical systems) is one of the most promising strategies for reducing greenhouse gas emissions associated with new buildings and building retrofits. Current methods used by engineers in assessing the opportunity to reuse building systems are often based on the calculation of their remaining service or economic lives. These methods are inadequate because they do not rely on the evaluation of the physical and technological degradation levels of building systems. Moreover, they do not distinguish between the different reuse pathways (i.e., direct reuse, repair, and upgrade).

This study aims to develop a method for identifying reuse pathways for building systems based on their physical reliability and their technological performance. The proposed method relies on the determination of failure rates and rates of successive generation release (i.e., the rates at which a successive generation of a product is released on the market). These are respectively derived from reliability databases and historical analyses of regulations and standards. The user is required to provide a minimum of field data and can provide more details if available. This information is used to calculate physical reliability and technological performance metrics, which form the basis on which reuse pathways are identified.

The proposed method is applied to a 9-year-old chiller installed in an office building scheduled for refurbishment in Brussels, Belgium. Results show that the proposed method provides the engineer with richer and more accurate information. While existing methods would simply recommend the reuse of the chiller, the compressor and the condenser, the proposed method recommends the repair and upgrade of the chiller, the upgrade of the compressor and the repair of the condenser.


Sébastien Loreau is a PhD candidate at the Université Catholique de Louvain in Belgium. He is affiliated with the Faculty of Architecture, Architectural Engineering and Urban Planning. He joined in February 2021 to start his research project entitled RESERVICE.

The project investigates the feasibility and the effects of reusing building systems in office buildings. It is an applied research project involving Cenergie, an engineering consultancy in Belgium, as an industrial partner. The project is under the supervision of Prof. André Stephan at the Université Catholique de Louvain, who is an international expert in life cycle assessment, Prof. Daniel Cooper at the University of Michigan, who is an international expert in material flow analysis, and Anne-Laure Maerckx, who is a senior consultant at Cenergie. The project is funded by Innoviris, which is the Brussels Region’s public institution for research and innovation.

Sébastien graduated in 2010 as an architectural engineer from the Université Libre de Bruxelles in Belgium. He was introduced to circular economy principles during his master’s thesis, undertaken under the supervision of Dr. Caroline Henrotay. After his graduation, he joined JZH, an engineering consultancy in Belgium, as a building systems engineer. For seven years, he developed strong technical and commercial autonomy in his field. Eager for a new challenge, he then moved to New Zealand where he joined WSP, a worldwide renowned engineering consultancy. He gained a new perspective on the field of building systems engineering and developed the willingness to investigate the application of circular economy principles to building systems. Before starting his PhD, he worked for two years as a sustainable construction consultant at 3E, an international engineering consultancy, where he acquired knowledge of life cycle assessment methods.

In his personal life, Sébastien likes to travel and play sports. He has visited many places including New Zealand, Colombia, Nepal, etc. He has been playing hockey since he was five years old. He currently plays in the hockey team of Waterloo.