Net Zero Energy Buildings

A net zero energy building produces as much energy as it uses over the course of a year. Net zero energy buildings are designed to be extremely energy efficient and have low energy requirements. To meet the remaining energy needs, net zero energy buildings typically use renewable energy generated on site. Despite the interest in zero energy buildings, there is no common definition, or even a common understanding, of what the term means. Following are several definitions of net zero energy buildings.

Determining Net Zero Energy Buildings

Net zero energy buildings can be defined in a number of ways, depending on overall goals. Each type of building has merit and value in reducing energy impact. A building may meet multiple zero energy building definitions. The more definitions it meets, the more merit it has as a zero energy building. For more information about zero energy building definitions, see the report Zero Energy Buildings: A Critical Look at the Definition (PDF 477 KB) on the National Renewable Energy Laboratory Web site. Download Adobe Reader.

Net Zero Site Energy

A site zero energy building produces at least as much energy as it uses in a year, when accounted for at the site. Typically the measurement time frame is annual.

Net Zero Source Energy

A source zero energy building produces at least as much energy as it uses in a year, when accounted for at the source. Source energy refers to the primary energy required to generate and deliver the energy to the site. To calculate a building's total source energy, imported and exported energy is multiplied by the appropriate site-to-source conversion multipliers.

Net Zero Energy Costs

In a net zero energy costs building, the amount of money the utility pays the building owner for the energy the building exports to the grid is at least equal to the amount the owner pays the utility for the energy services and energy used over the year.

Net Zero Energy Emissions

A net-zero energy emissions building produces at least as much emissions-free renewable energy as it uses from emission-producing energy sources annually.

To learn more, see examples of Zero Energy Buildings.