Net Zero Energy

A net zero-energy building (ZEB) is a residential or commercial building that has reduced its energy needs through efficiency gains. At the heart of the net zero energy concept is the idea that buildings can meet all their energy requirements from low-cost, locally available, nonpolluting, renewable sources. At the strictest level, a ZEB generates enough renewable energy on site to equal or exceed its annual energy use. There are multiple definitions of net zero energy:

• Net Zero Site: This building produces at least as much energy as it uses in a year, when accounted for at the site
• Net Zero Source: This 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 used 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 Cost: 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 Emissions: A net-zero emissions building produces at least as much emissions-free renewable energy as it uses from emissions-producing energy sources.

For more information: NREL: Zero Energy Buildings: A Critical Look at the Definition