The Building Circularity Index (BCI) is a metric used to assess the level of circularity and sustainability of a building or construction project. It quantifies the extent to which materials, resources, and components within the building's lifecycle are reused, recycled, or repurposed, minimizing waste and environmental impact. BCI provides a quantifiable score that indicates the extent to which a building follows circular principles. A higher BCI score implies a greater level of circularity and sustainability.

BCI aims to promote more sustainable construction practices by encouraging the design, construction, and operation of buildings that prioritize circular economy principles, such as reducing resource consumption and extending the lifespan of materials.