Net zero buildings don't just practice energy efficiency, aim for LEED certification, install solar panels, etc. these buildings actually use no net energy from the grid, or go even further in their "zero" duties. Typically a net zero building will leverage on-site renewable energy to generate enough power to cover all of the building's energy consumption. Some net zero buildings will also use off-site renewable energy or renewable energy certificates to supplement the building’s energy generation, but all of the building's energy use must come from renewable sources to be considered “net zero”.
While some net zero buildings may leverage the grid, others are entirely "self-reliant" and can operate independent of the grid. There are additional "zero" considerations that ZEBs can achieve as well:
- Site ZEB: A building that produces at least as much energy as it uses in a year, when accounted for at the site. This is what is described above and is required in net zero buildings.
- Source ZEB: A building that produces at least as much energy as it uses in a year, when accounted for at the source. "At the source" means including the energy used to transport the energy to the building, which accounts for transmission loss during delivery of the electricity from the plant to the building. Such losses can be significant, as much as 6.5%.
- Emissions (carbon) ZEB: A building that produces at least as much emissions-free renewable energy as it uses from emission-producing energy sources annually.
The following buildings are some of the most well-known net zero energy buildings, each with an array of unique and innovative features that take green building to the next level.
Beddington Zero Energy DevelopmentBedZED in Hackbridge, London
It’s a mixed use development, holding 82 homes and 15,120 square feet of work space. The buildings use a mix of 8,360 square feet of solar panels, a cogeneration plant fueled by tree waste, and district heating and electricity. Their passive solar design and highly insulated and triple glazed windows make them highly energy efficient, and able to run on only the energy produced on site.
The development has a number of other sustainability features in addition to net zero energy, such as on-site rainwater collection and reuse, walkable design with a car sharing program, and materials sourced locally (within 35 miles of the site).
BedZED is prominent because it was one of the first developments of its kind, built between 2000 and 2002. It was designed by forward-thinking architect Bill Dunster, and has a unique appearance, especially because of its wind driven cowls on the roof, which allow passive ventilation.
Hawaii Gateway Energy Center Photo credit: Ferraro Choi and Associates, Ltd.
Designed by Ferraro Choi and Associates, Ltd. it is the first building to be constructed on a 6.5 acre campus designed to house research, development, and demonstration facilities for energy and technological fields.
The HGEC is a sustainable, zero-net energy multi-use facility that engages in various distributed and renewable energy research, generation, development, demonstration, education, and outreach activities. NELHA is the acronym for Natural Energy Laboratory of Hawaii Authority, the State agency that operates the Natural Energy Laboratory of Hawaii and harvests cold, deep seawater from depths of up to 3,000 feet below sea level.
The NELH facilities are run by the State of Hawaii under the Natural Energy Laboratory of Hawaii Authority (NELHA). The visitor complex houses administrative office space, restrooms, support areas, and a large multi-purpose space that will be used for displays, outreach, conferencing, and education. The first phase of the plan for the site also includes a small research laboratory facility. The second phase will add more laboratory space to complete the campus.
Center for Sustainable Landscapes at Phipps Conservatory "Romero" in bloom at Phipps
The building has cut energy use by 50% compared to traditional buildings, thanks to its passive solar design, a robust building envelope with high performance insulation and low-e windows, and a rooftop energy recovery unit (which pre-cools or pre-heats air as necessary before it enters the building).
The Phipps Conservatory also uses natural ventilation and demand-controlled ventilation based on CO2 sensors installed in some rooms. Its atrium is air conditioned using 100% passive strategies. It has a solar PV system, vertical axis wind turbines, solar hot water and 14 geothermal wells that supply all of the building’s energy.
The ventilation may be very helpful right about now, as the Phipps Conservatory is hosting the blooming of an Amorphophallus Titanum, aka the "Corpse Flower", a rare flower that blooms approximately every ten years and gives off a stench some say is akin to rotting flesh. This corpse flower has been named "Romero" after George Romero, director of "Night of the Living Dead", a Pittsburgh native.
Center for Interactive Research on Sustainability (CIRS) CERS Building by Perkins & Will
CIRS is not only net zero, it is net positive, meaning that it generates more energy than it consumes. It has 30 vertical geoexchange wells and windows that incorporate solar PV screens. Its energy efficient features include daylighting (with see-through floors for light transfer), and a naturally ventilated atrium.
The Centre is experimenting with many innovative sustainability technologies. For example, wastewater is collected and treated using a solar aquatic biofiltration system, and is then reused for toilet flushing and irrigation. In the summer, a living vegetated wall shades interior spaces, but in the winter, it drops its leaves and allows the sunlight in to warm the space. It also uses beetle kill pine, which is a species of wood that has been killed by a beetle invasion - making it arguably more sustainable than FSC-certified wood (which has been certified as sustainably harvested).
Environmental Technology Center
ETC achieved this through the use of energy-efficient techniques such as a tight building envelope, thermal mass, shading, and other features. ETC includes a 3-kW rooftop photovoltaic (PV) system that is tied to the grid and is a net energy exporter. So, this building qualifies as a net zero energy building (ZEB) in the following areas:
- ETC produces at least as much energy as it uses in a year, when accounted for at the site. ETC produces all of its needed electricity through a PV system that is within the building’s footprint. Any natural gas used for domestic hot water and radiant heat is also offset at the site by PV generation.
- Source ZEB: Building produces at least as much energy as it uses in a year, when accounted for at the source. ETC is considered a source ZEB because the energy generated on-site through PV is greater than the energy used when accounted for at the source. .
- Emissions ZEB: Building produces at least as much emissions-free renewable energy as it uses from emission-producing energy sources annually. ETC offsets any emissions for which it is responsible through its PV system which produces electricity with zero emissions. .
Bullitt Center Bullitt Center
Opened in April 2013, the building is aiming to achieve certification through the Living Building Challenge, which is the most difficult green building certification program in the world. The building must be monitored by the International Living Building Institute, the organization that created the certification, for one full year before it can achieve Living Building status, but it was designed to meet the strict criteria. If it earns certification, it will be the largest Living Building in the world.
One requirement for full certification as a Living Building is that it must be net zero. The Bullitt Center uses solar PV panels and geothermal wells to supply the building’s energy, which is 1/3 of the energy use of a typical office building. It used design strategies such as daylighting that helped it cut down energy demand. Aside from net zero, the building also has many other green features, like on-site wastewater treatment and rainwater collection and reuse.
Learn More About Net Zero Buildings
It also discusses certifications for Net Zero buildings, which include the Living Building Challenge and Net Zero Building certification.