A building approaching zero energy use may be called a near-zero energy building or ultra-low energy house. Buildings that produce a surplus of energy during a portion of the year may be known as energy-plus buildings. An energy autarkic house is a building concept where the balance of the own energy consumption and production can be made on an hourly or even smaller basis. Energy autarkic houses can be taken off-the-grid.
Zero Energy Buildings are usually built with significant energy-saving features. The heating and cooling loads are often drastically lowered by using high-efficiency equipment, added insulation, high-efficiency windows, passive solar techniques, and other techniques. These features can vary drastically between buildings in different climate zones. Water heating loads can be alleviated by using heat recovery units on waste water, and by using high-efficiency water heating equipment. In addition, lighting energy use can be lessened by daylighting, fluorescent and LED lighting, and miscellaneous electric loads can be lessened by choosing efficient appliances and minimizing standby power. Zero energy buildings are often designed to make use of energy gained from other sources including white goods; for example, use refrigerator exhaust to heat domestic hot water, ventilation air and shower drain heat exchangers, office machines and computer servers, and even body heat from rooms with multiple occupants. These buildings make use of heat energy that conventional buildings typically exhaust outside. They may use heat recovery ventilation, hot water heat recycling, and absorption chiller units. They are normally optimised to use passive solar heat gain, use thermal mass to stabilise diurnal temperature variations throughout the day, and in most climates are superinsulated. All the technologies needed to create zero energy buildings are available off-the-shelf today.
Zero Energy Production, in commercial and industrial applications. Taking into account the diverse topography of each location and designing a renewable energy development approach to satisfy the production energy required to develop each product. This production energy always reduces the profitability of each facility constructed in the past. With Zero Energy Production comes the arena of placing Geothermal, Microhydro, Solar, and Wind resources to lower the initial impact of each facilities requirement to be self sustainable using only sustainable energy.
Zero-energy neighborhoods, such as the BedZED development in the United Kingdom, and those that are spreading rapidly in California and China, may use distributed generation schemes. This may in some cases include district heating, community chilled water, shared wind turbines, etc. There are current plans to use ZEB technologies to build entire off-the-grid cities, such as the photovoltaic-powered Huangbaiyu Sustainable Village, and the planned Dongtan Eco-City near Shanghai.
As a result of significant government subsidies for photovoltaic solar electric systems, wind turbines, etc., there are those who suggest that a ZEB is a conventional house with distributed renewable energy generation. Entire additions of such homes have appeared in locations such as California and other locations where photovoltaic (PV) subsidies are significant, but many so called "Zero Energy Homes" still have utility bills. This type of energy generation without energy conservation may not be cost effective with the current price of photovoltaic equipment (depending on the local price of power company electricity) , and also requires greater embodied energy and greater resources and is thus the lesser ecological approach..
For three decades, passive solar building design has demonstrated energy consumption reductions of 70% to 90% in many locations, without using any active power generation systems. With expert design, this can be accomplished with little additional new construction cost for materials over a conventional building, but very few industry experts have the skills or experience to do this. Such passive solar designs are much more cost effective than adding expensive photovoltaic panels on the roof of a conventional inefficient building. A few kWh of photovoltaic panels (costing tens of thousands of U.S. dollar equivalent) may only reduce external energy requirements by 15% to 30%. A 100,000 BTU high seasonal energy efficiency ratio 14 conventional air conditioner requires over 7 kW of photovoltaic electricity while it is operating, and that does not include enough for off-the-grid night time operation. Using passive cooling, and superior system engineering techniques, can reduce the air conditioning requirement by 70% to 90%, where photovoltaic electricity then becomes more cost-effective.
Those who commissioned construction of Passive Houses and Zero Energy Homes (over the last three decades) were essential to iterative, incremental, cutting-edge, technology innovations. Much has been learned from many significant successes, and a few expensive failures.
The zero energy building concept has been a progressive evolution from other low-energy building designs. Among these, the Canadian R-2000 and the German passive house standards have been internationally influential. Collaborative government demonstration projects, such as the superinsulated Saskatchewan House, and the International Energy Agency's Task 13, have also played their part.
The 1999 side-by-side Florida Solar Energy Center Lakeland Florida demonstration project was called the "Zero Energy Home." It was a first-generation university effort that significantly influenced the creation of the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Zero Energy Home program. George Bush's Solar America Initiative is funding research and development into widespread near-future development of cost-effective Zero Energy Homes in the amount of $148 million in 2008 .
One example of the new generation of zero energy office buildings is the 71-story Pearl River Tower, which is scheduled to open in 2009, as the Guangdong Company headquarters. It uses both high energy efficiency, and distributed renewable energy generation from both solar and wind. Built by Skidmore Owings Merrill LLP in Guangzhou, China, the tower is receiving economic support from government subsidies that are now funding many significant conventional fossil-fuel (and nuclear energy) energy reduction efforts.
One of the first zero-energy commercial buildings in the United States is Integrated Design Associates (IDeAs) Z-Squared Design Facility. Opened and occupied as of October 2007, this San Jose, California building was designed to meet a net-zero-energy/zero-carbon-emissions (Z-squared) target. Notably, it is a remodel of a commonplace 1960’s-era tilt-up concrete structure that once served as a corner bank. Z-squared performance was achieved through simple, affordable strategies, including daylighting, radiant heating, ground source heat pump cooling, advanced insulation and glazing and reduced computer and appliance loads through careful equipment selection and wiring.
Googleplex, Google's headquarters in Mountain View, California, completed a 1.6 megawatt photovoltaic campus-wide renewable power generation system. Google (and others) have developed advanced technology for major reductions in computer-server energy consumption (which is becoming a major portion of modern zero-energy commercial building design, along with daylighting and efficient electrical lighting systems).
Wide acceptance of zero energy building technology may require more government incentives or building code regulations, the development of recognised standards, or significant increases in the cost of conventional energy.
The Google photovoltaic campus, and the Microsoft 480-kilowatt photovoltaic campus relied on U.S. Federal, and especially California, subsidies and financial incentives. California is now providing $3.2 billion USD in subsidies for residential-and-commercial near-zero-energy buildings, due to California's serious electricity shortage, frequent power outages, and air pollution problems. The details of other American states' renewable energy subsidies (up to $5.00 USD per watt) can be found in the Database of State Incentives for Renewables and Efficiency. The Florida Solar Energy Center has a slide presentation on recent progress in this area.
The World Business Council for Sustainable Development has launched a major initiative to support the development of ZEB. Led by the CEO of United Technologies and the Chairman of Lafarge, the organization has both the support of large global companies and the expertise to mobilize the corporate world and governmental support to make ZEB a reality. Their first report, a survey of key players in real estate and construction, indicates that the costs of building green are overestimated by 300 percent. Survey respondents estimated that greenhouse gas emissions by buildings are 19 percent of the worldwide total, in contrast to the actual value of roughly 40 percent.
The goal of green building and sustainable architecture is to use resources more efficiently and reduce a building's negative impact on the environment. Zero energy buildings achieve one green-building goal of significantly reducing energy use and greenhouse gas emissions. Zero energy buildings, however, are not necessarily green, because in order to achieve net zero energy use or carbon emissions, buildings do not require other green building practices such as reducing waste, using recycled building materials, etc.
Similarly, green building certification does not require a building to have net zero energy use, only to reduce energy use. Green building council certification criteria (such as the Leadership in Energy and Environmental Design Green Building Rating System, developed by the U.S. Green Building Council) involve evolving check lists that reduce the impact of new buildings on the environment, while improving environmental sustainability. Sustainable architecture, sustainable design, and natural building all embrace similar goals and solution concepts. The computer models used to evaluate green building design do not include the thermal science and architectural design patterns necessary to evaluate state-of-the-art passive solar building design or zero energy design.
One green building limitation is that the potentially-complex thermal physics necessary for zero energy design is not part of the required formal education for professional architects. Thus, the knowledge of zero energy design is less common than the basics of green building.
"Self-Sufficient Solar House " Fraunhofer Institute's (ZEB), Freiburg, Germany
DOE is also awarding $4.1 million to two regional building technology application centers that will accelerate the adoption of new and developing energy-efficient technologies. The two centers, located at the University of Central Florida and Washington State University, will serve 17 states, providing information and training on commercially available energy-efficient technologies.
According to Energy Design Update (February 2007), one home in the United States has demonstrated 12 months of data showing net-zero-energy performance; that house, located in Wheat Ridge, Colorado, was built by Metro Denver Habitat for Humanity, with help from NREL engineers.
The U.S. Energy Independence and Security Act of 2007 created 2008 through 2012 funding for a new solar air conditioning research and development program, which should soon demonstrate multiple new technology innovations and mass production economies of scale.
One of the most comprehensive modern compilations of information on this subject is the U.S. Department of Energy (DOE) Oak Ridge National Laboratory (ORNL) Building Technology group "Thermal Performance of the Exterior Envelopes of Whole Buildings Tenth International Conference" held December 2007. The popular Zero Energy Design DOE/ORNL Workshop materials include an 800-page eBook, 500 presentation slides, and related support materials.