Anne Carrier Architectes completed the expansion of Bibliotheque L'Octogone in Montreal's LaSalle borough, nearly doubling its size from 2,645 to 4,500 square meters. The project added a new floor and three architectural lanterns while preserving the original octagonal structure. By reusing the existing concrete slab and structural framework, the design avoided 261,000 kilograms of carbon emissions and kept 870 cubic meters of construction waste out of landfills. This approach shows how civic building renovations can cut embodied carbon without sacrificing design quality. The project kept the original octagonal volume intact and extended it, which saved materials and reduced emissions compared to a full demolition and rebuild. For architects and construction firms looking to lower the carbon footprint of public infrastructure, this project offers a concrete example of how structural reuse can work at scale.
