“A site ZEB produces at least as much energy as it uses in a year, when accounted for at the site.”
Energy flows are accounted at the site of the project. A building using 100 kWh of energy annually will be site net zero energy if at least 100 kWh of renewable energy is produced at the site annually. Renewable energy supply systems can be installed on building rooftops, facades, parking lots and other open areas in the site.
Site NZEBs encourage a relentless pursuit of energy efficiency, as the quantum of renewable energy supply options on a given site are limited.
Net zero site energy buildings ignore source energy. Energy used in producing and transmitting grid supplied electricity from source to site are not accounted for while calculating demand-supply equilibrium. Energy spent in transporting renewable fuels like bio-waste to the site, is also not considered. This renders site NZEBs easier to implement because energy supply targets to reach neutrality are low.
Renewable energy sources that can be used on site are solar PV, wind, and biofuels. Technologies commonly used are solar PV, solar hot water, solar thermal, small hydro units, biogas plants and if the site location is conducive, then wind turbines.
Renewable energy produced is fed directly into the energy distribution system of the building. Surplus energy can either be stored in storage batteries or supplied to the grid if net metering and feed-in tariff policies are being implemented by local utilities.
This definition is more viable for small to medium sized buildings with comparatively large site areas and abundant supply of renewable sources like solar and wind.