As per the National Renewable Energy Laboratory (NREL) in the United States of America, Net-Zero Energy Buildings (NZEB) is a "building that offsets all of its energy use from renewable energy resources available within the footprint".Â
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NZEB can be interpreted as buildings that utilize renewable energy to satisfy building energy needs. It is a building that produces as much energy as its uses over the course of a year.Â
Statistical studies show that buildings are the primary energy consumers in the U.S. This fact emphasizes the importance of targeting building energy use as a key to decreasing the nation's energy consumption.
A Net Zero Energy Building combines ideal building design to minimize energy requirements and renewable energy systems to meet reduced energy needs.
Different Metrics of Net Zero Energy Buildings (NZEB)
- Net Zero Site Energy: This is the energy consumed and generated at site (building). It does not consider where and how the energy is originated. A net zero site energy building, must generate unit of energy for every unit of energy the building consumes.
- Net Zero Source Energy: It is the primary energy needed to extract and deliver energy to a site, including energy lost or wasted in the process of generation, transmission, and distribution. A net zero source energy building produce as much energy on an annual basis as it uses as compared to the energy content at the source.
- Net Zero Energy Costs: It is the simplest metric, where the building has an energy utility bill of $0 over the course of a year. This means, that all the energy required for the building is taken from the on-site renewable generation.
- Net Zero Energy Emissions: A net-zero energy emission building does not use energy that results in emissions i.e. it uses emissions-free energy.
Energy Efficiency of Net Zero Energy Buildings (NZEB)
- High-performance envelopes
- Daylighting
- Air barrier systems
- Passive solar heating
- Natural ventilation
- Water conservation
- Sun control and shading devices
- Energy efficient lighting
- High-performance HVAC
- Geothermal heat pumps
- Electric lighting controls
- Fuel cells
- Combined heat and power systems
- Microturbines