Hannon Armstrong Sustainable Infrastructure Capital (HASI) is a US Real Estate Investment Trust (REIT). The company focuses on renewable energy projects and real estate investments that serve to reduce energy use. HASI provides capital and services focused on reducing greenhouse gas emissions, as well as mitigating the impact of, or increasing resiliency to, climate change. Its objective is to generate attractive returns by investing capital in assets or projects that generate long-term, recurring and predictable cash flows or cost savings from proven technologies.

Its investments take various forms including equity, joint ventures, land ownership, lending and other financing transactions. HASI also generates ongoing fees through gain-on-sale securitization transactions, advisory services and asset management. In addition, the company provides services to the various partners and counter-parties in the markets where it invests. In total, HASI manages 260 investments with a weighted average life of 17 years (as of 2021).