This case study applies life-cycle assessment methods to the preliminary design of an office building in order to quantify the benefits achieved when reusing its load-bearing components. Results show that the production of the load-bearing system would account for 40% of the global warming potential indicator. The slabs are responsible for 65% of the environmental impacts among all structural elements and should be considered for reuse first. Compared to traditional constructions built from first-use material, a fictitious reuse of undamaged load-bearing components over three consecutive use cycles would reduce the global warming potential indicator by 25%. The global warming potential of reuse is eventually computed according to three repartition methods, highlighting the need to separate the life-cycle footprints related to production, use, and end-of-life more systematically.