building designed to generate at least as much renewable energy as is consumed. For questions about being [off-grid] use that tag.
Zero Energy buildings are more precisely described as Zero Net Energy buildings, but zero energy (ZE) remains a common descriptor in the areas of construction and architecture. Low-energy and ultra-low-energy buildings have similar design goals, but are held to less stringent criteria.
The key defining trait of a zero energy building is that total annual energy usage is less than the amount of energy produced locally by renewable resources. For off-grid buildings, this means that energy from fossil-fuel burning generators must be offset by local production. For grid-connected buildings, this means that annual export of energy to the grid must exceed imports.
A defining strategy for achieving zero net energy is to maximize advantage from sunlight. This principle leads to choices such as improved insulation, better window placement and overhang design (to provide heat, reduce cooling demand, and provide lighting), use of photovoltaic arrays, and strategic placement of landscape or greenery to provide shading or evaporative cooling.
Zero energy building design does not imply that occupants must avoid use of electricity and other kinds of energy. Rather, a zero energy building ensures that all demands are met by using resources within the boundary of the building and by focusing on energy efficiency and conservation.
The term "zero energy" is not typically used when describing cars or other modes of transport.