SUSTAINABILITY, ENVIRONMENTAL RESPONSIBILITY, AND CIRCULAR BUSINESS MODELS

Sustainability raises a problem that ordinary profit-and-loss statements cannot settle: whether an enterprise can create durable value without imposing unacceptable ecological depletion, uncompensated harm, or unjust burdens on others and future generations. This chapter develops an analytically rigorous account of sustainability, environmental responsibility, and circular business models across twelve interconnected domains. A transparent, purposive synthesis of foundational scholarship, peer-reviewed empirical research, official statistics, international standards, and dated Rwandan policy documents brings externality economics, stakeholder theory, ecological limits, industrial ecology, materiality, and circular-economy scholarship into critical dialogue. It distinguishes sustainability performance from reporting activity, material recirculation from absolute impact reduction, and financial exposure from wider social and ecological significance. Rwanda's National Circular Economy Action Plan, revised Green Growth and Climate Resilience Strategy, and 2035 nationally determined contribution are considered alongside contemporary international disclosure and environmental-management requirements. An explicitly hypothetical Rwandan beverage-packaging case compares single-use glass with a managed refill system through reproducible material-flow, emissions, financial, return-rate, and sensitivity calculations. Original instruments include a life-cycle decision map, impact-and-exposure matrix, environmental indicator register, and green-claims substantiation protocol. The central argument is conditional: an enterprise can responsibly pursue resource productivity and circular innovation only when physical impacts, economic feasibility, human consequences, governance, and credible evidence are evaluated together. The chapter proposes a testable cross-functional synthesis; it does not claim new empirical validation.