Green building is the practice of increasing the efficiency of buildings and their use of energy, water, and materials, and reducing building impacts on human health and the environment, through better siting, design, construction, operation, maintenance, and removal -- the complete building life cycle.

A similar concept is natural building, which is usually on a smaller scale and tends to focus on the use of natural materials that are available locally. Other commonly used terms include sustainable design and green architecture.

While good design is essential to green building, the actual operation, maintenance, and ultimate disposal or deconstruction of the building also have very significant effects on the building's overall environmental impact. 

The related concepts of sustainable development and sustainability are
integral to green building. Effective green building can result in:

Reduced operating costs by increasing productivity and using less energy and water.

Improved public and occupant health due to improved indoor air quality.

Reduced environmental impacts by, for example, lessening storm water runoff and the heat island effect.

Practitioners of green building often seek to achieve not only ecological but also an aesthetic harmony between a structure and its surrounding natural and built environment. The sustainable buildings are also environmentally friendly in the fact that they are built out of materials that are good for the environment. The appearance and style of sustainable buildings can be nearly indistinguishable from their less sustainable counterparts.

Green buildings are scored by rating systems, such as the Leadership in Energy and Environmental Design (LEED) rating system developed by the U.S. Green Building Council, Green Globes from GBI and other locally developed rating systems.