Zero energy building - AbsoluteAstronomy.com

A zero-energy building, also known as a zero net energy (ZNE) building, Net-Zero Energy Building (NZEB), or Net Zero Building, is a popular term to describe a building

Building

In architecture, construction, engineering, real estate development and technology the word building may refer to one of the following:...

with zero net energy consumption and zero carbon emissions annually. Zero energy buildings can be independent from the energy grid supply. Energy can be harvested on-site—usually through a combination of energy producing technologies like Solar and Wind—while reducing the overall use of energy with extremely efficient HVAC

HVAC

HVAC refers to technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer...

and Lighting technologies. The zero-energy design principle is becoming more practical to adopt due to the increasing costs of traditional fossil fuels and their negative impact on the planet's climate and ecological balance.

The zero net energy consumption principle is gaining considerable interest as renewable energy harvesting is a means to cut greenhouse gas emissions. Traditional building consumes 40% of the total fossil energy in the US and European Union.

Modern evolution

The development of modern zero-energy buildings became possible not only through the progress made in new construction technologies and techniques, but it has also been significantly improved by academic research on traditional and experimental buildings, which collected precise energy performance data. Today's advanced computer models can show the efficacy of engineering design decisions.

Energy use can be measured in different ways (relating to cost, energy, or carbon emissions) and, irrespective of the definition used, different views are taken on the relative importance of energy harvest and energy conservation to achieve a net energy balance. Although zero energy buildings remain uncommon in developed countries

Developed country

A developed country is a country that has a high level of development according to some criteria. Which criteria, and which countries are classified as being developed, is a contentious issue...

, they are gaining importance and popularity. The zero net energy approach has potential to reduce carbon emissions

Carbon dioxide

Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

, and reduce dependence on fossil fuel

Fossil fuel

Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...

s.

A building approaching zero net 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

Energy-plus-house

An energy-plus-house produces more energy from renewable energy sources, over the course of a year, than it imports from external sources. This is achieved using a combination of microgeneration technology and low-energy building techniques, such as: passive solar building design, insulation and...

".

If the building is located in an area that requires heating or cooling throughout parts of the year, it is easier to achieve zero net energy consumption when the available living space is kept small.

Definitions

Despite sharing the name "zero net energy", there are several definitions of what the term means in practice, with a particular difference in usage between North America and Europe.

Zero net site energy use: In this type of ZNE, the amount of energy provided by on-site renewable energy

Renewable energy

Renewable energy is energy which comes from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable . About 16% of global final energy consumption comes from renewables, with 10% coming from traditional biomass, which is mainly used for heating, and 3.4% from...

sources is equal to the amount of energy used by the building. In the United States, “zero net energy building” generally refers to this type of building.

Zero net source energy use: This ZNE generates the same amount of energy as is used, including the energy used to transport the energy to the building. This type accounts for losses during electricity transmission

Electric power transmission

Electric-power transmission is the bulk transfer of electrical energy, from generating power plants to Electrical substations located near demand centers...

. These ZNEs must generate more electricity than zero net site energy buildings.

Net zero energy emissions: Outside the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

and Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, a ZEB is generally defined as one with zero net energy emissions, also known as a zero carbon building or zero emissions building. Under this definition the carbon emissions generated from on-site or off-site fossil fuel use are balanced by the amount of on-site renewable energy

Renewable energy

production. Other definitions include not only the carbon emissions generated by the building in use, but also those generated in the construction of the building and the embodied energy

Embodied energy

Embodied energy is defined as the sum of energy inputs that was used in the work to make any product, from the point of extraction and refining materials, bringing it to market, and disposal / re-purposing of it...

of the structure. Others debate whether the carbon emissions of commuting

Commuting

Commuting is regular travel between one's place of residence and place of work or full time study. It sometimes refers to any regular or often repeated traveling between locations when not work related.- History :...

to and from the building should also be included in the calculation.

Net zero cost: In this type of building, the cost of purchasing energy is balanced by income from sales of electricity to the grid of electricity generated on-site. Such a status depends on how a utility credits net electricity generation and the utility rate structure the building uses.

Net off-site zero energy use: A building may be considered a ZEB if 100% of the energy it purchases comes from renewable energy sources, even if the energy is generated off the site.

Off-the-grid:Off-the-grid

Off-the-grid

The term off-the-grid or off-grid refers to living in a self-sufficient manner without reliance on one or more public utilities....

buildings are stand-alone ZEBs that are not connected to an off-site energy utility facility. They require distributed renewable energy generation and energy storage capability (for when the sun is not shining, wind is not blowing, etc.). An energy autarkic

Autarky

Autarky is the quality of being self-sufficient. Usually the term is applied to political states or their economic policies. Autarky exists whenever an entity can survive or continue its activities without external assistance. Autarky is not necessarily economic. For example, a military autarky...

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.

Design and construction

The most cost-effective steps toward a reduction in a building's energy consumption usually occurs during the design process. To achieve efficient energy use, zero energy design departs significantly from conventional construction practice. Successful zero energy building designers typically combine time tested passive solar, or natural conditioning, principles that work with the on site assets. Sunlight and solar heat, prevailing breezes, and the cool of the earth below a building, can provide daylighting and stable indoor temperatures with minimum mechanical means. ZEBs are normally optimized to use passive solar heat gain and shading, combined with thermal mass

Thermal mass

Thermal mass is a concept in building design which describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect...

to stabilize diurnal temperature variation

Diurnal temperature variation

Diurnal temperature variation is a meteorological term that relates to the variation in temperature that occurs from the highs of the day to the cool of nights.-Temperature lag:Temperature lag is an important factor in diurnal temperature variation...

s throughout the day, and in most climates are superinsulated

Superinsulation

Superinsulation is an approach to building design, construction, and retrofitting that dramatically reduces heat loss by using much higher levels of insulation and airtightness than normal...

. All the technologies needed to create zero energy buildings are available off-the-shelf

Commercial off-the-shelf

In the United States, Commercially available Off-The-Shelf is a Federal Acquisition Regulation term defining a nondevelopmental item of supply that is both commercial and sold in substantial quantities in the commercial marketplace, and that can be procured or utilized under government contract...

today.

Sophisticated 3D computer simulation

Computer simulation

A computer simulation, a computer model, or a computational model is a computer program, or network of computers, that attempts to simulate an abstract model of a particular system...

tools are available to model how a building will perform with a range of design variables such as building orientation (relative to the daily and seasonal position of the sun

Sun

The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

), window and door type and placement, overhang depth, insulation type and values of the building elements, air tightness (weatherization

Weatherization

Weatherization or weatherproofing is the practice of protecting a building and its interior from the elements, particularly from sunlight, precipitation, and wind, and of modifying a building to reduce energy consumption and optimize energy efficiency.Weatherization is distinct from building...

), the efficiency of heating, cooling, lighting and other equipment, as well as local climate. These simulations help the designers predict how the building will perform before it is built, and enable them to model the economic and financial implications on building cost benefit analysis, or even more appropriate - life cycle assessment.

Zero-energy buildings are built with significant energy-saving features. The heating and cooling loads are lowered by using high-efficiency equipment, added insulation

Building insulation

building insulation refers broadly to any object in a building used as insulation for any purpose. While the majority of insulation in buildings is for thermal purposes, the term also applies to acoustic insulation, fire insulation, and impact insulation...

, high-efficiency windows, natural ventilation, and other techniques. These features vary depending on climate zones in which the construction occurs. Water heating loads can be lowered by using water conservation fixtures, heat recovery units on waste water, and by using solar water heating, and high-efficiency water heating equipment. In addition, daylighting

Daylighting

Daylighting is the practice of placing windows or other openings and reflective surfaces so that during the day natural light provides effective internal lighting. Particular attention is given to daylighting while designing a building when the aim is to maximize visual comfort or to reduce energy...

with skylites or solartubes can provide 100% of daytime illumination within the home. Nighttime illumination is typically done with fluorescent

Fluorescent lamp

A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful...

and LED

LED lamp

An LED lamp is a solid-state lamp that uses light-emitting diodes as the source of light. The LEDs involved may be conventional semiconductor light-emitting diodes, organic LEDs , or polymer light-emitting diodes devices, although PLED technologies are not currently commercially available.Since...

lighting that use 1/3 or less power than incandescent lights, without adding unwanted heat. And miscellaneous electric loads can be lessened by choosing efficient appliances and minimizing phantom loads or standby power

Standby power

Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity , refers to the electric power consumed by electronic and electrical appliances while they are switched off Standby power, also called vampire power, vampire draw, phantom load, or leaking electricity...

. Other techniques to reach net zero (dependent on climate) are Earth sheltered building principles, superinsulation walls using straw-bale construction

Straw-bale construction

Straw-bale construction is a building method that uses bales of straw as structural elements, building insulation, or both...

, Vitruvianbuilt pre-fabricated building panels and roof elements plus exterior landscaping for seasonal shading.

Zero-energy buildings are often designed to make dual use of energy including white goods; for example, using refrigerator exhaust to heat domestic water, ventilation air and shower drain heat exchanger

Heat exchanger

A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall, so that they never mix, or they may be in direct contact...

s, office machines and computer servers, and body heat to heat the building. These buildings make use of heat energy that conventional buildings may exhaust outside. They may use heat recovery ventilation

Heat recovery ventilation

Heat recovery ventilation, also known as HRV, mechanical ventilation heat recovery, or MVHR, is an energy recovery ventilation system using equipment known as a heat recovery ventilator, heat exchanger, air exchanger, or air-to-air heat exchanger which employs a counter-flow heat exchanger between...

, hot water heat recycling

Hot water heat recycling

Water heat recycling is the use of a heat exchanger to recover energy and reuse heat from drain water from various activities such as dish-washing, clothes washing and especially showers...

, combined heat and power

Combined Heat and Power

Combined Heat and Power may refer to:* Cogeneration* Combined Heat and Power Solar...

, and absorption chiller units.

Energy harvest

ZEBs harvest available energy to meet their electricity and heating or cooling needs. In the case of individual houses, various microgeneration

Microgeneration

Microgeneration is the small-scale generation of heat and power by individuals, small businesses and communities to meet their own needs, as alternatives or supplements to traditional centralized grid-connected power...

technologies may be used to provide heat and electricity to the building, using solar cell

Solar cell

A solar cell is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect....

s or wind turbine

Wind turbine

A wind turbine is a device that converts kinetic energy from the wind into mechanical energy. If the mechanical energy is used to produce electricity, the device may be called a wind generator or wind charger. If the mechanical energy is used to drive machinery, such as for grinding grain or...

s for electricity, and biofuel

Biofuel

Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases...

s or solar collector

Solar collector

-See also:*Solar thermal collector*Solar water heating*Solar air heating*Photovoltaic module*Renewable heat*Concentrating solar power...

s linked to seasonal thermal store

Seasonal thermal store

A seasonal thermal store is a store designed to retain heat deposited during the hot summer months for use during colder winter weather...

s for space heating. To cope with fluctuations in demand, zero energy buildings are frequently connected to the electricity grid, export electricity to the grid when there is a surplus, and drawing electricity when not enough electricity is being produced. Other buildings may be fully autonomous

Autonomous building

An autonomous building is a building designed to be operated independently from infrastructural support services such as the electric power grid, gas grid, municipal water systems, sewage treatment systems, storm drains, communication services, and in some cases, public roads.Advocates of...

.

Energy harvesting is most often more effective (in cost and resource utilization) when done on a local but combined scale, for example, a group of houses, co-housing, local district, village, etc. rather than an individual basis. An energy benefit of such localized energy harvesting is the virtual elimination of electrical transmission and electricity distribution

Electricity distribution

File:Electricity grid simple- North America.svg|thumb|380px|right|Simplified diagram of AC electricity distribution from generation stations to consumers...

losses. These losses amount to about 7.2%-7.4% of the energy transferred. Energy harvesting in commercial

Commerce

While business refers to the value-creating activities of an organization for profit, commerce means the whole system of an economy that constitutes an environment for business. The system includes legal, economic, political, social, cultural, and technological systems that are in operation in any...

and industrial

Industry

Industry refers to the production of an economic good or service within an economy.-Industrial sectors:There are four key industrial economic sectors: the primary sector, largely raw material extraction industries such as mining and farming; the secondary sector, involving refining, construction,...

applications should benefit from the topography

Topography

Topography is the study of Earth's surface shape and features or those ofplanets, moons, and asteroids...

of each location. The production of goods under net zero fossil energy consumption requires locations of geothermal

Geothermal power

Geothermal energy is thermal energy generated and stored in the Earth. Thermal energy is the energy that determines the temperature of matter. Earth's geothermal energy originates from the original formation of the planet and from radioactive decay of minerals...

, microhydro, solar, and wind

Wind

Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...

resources to sustain the concept.

Zero-energy neighborhoods, such as the BedZED

BedZED

Beddington Zero Energy Development is an environmentally friendly housing development in Hackbridge, London, England. It is in the London Borough of Sutton. It was designed by the architect Bill Dunster to support a more sustainable lifestyle...

development in the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, and those that are spreading rapidly in California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

and China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

, may use distributed generation

Distributed generation

Distributed generation, also called on-site generation, dispersed generation, embedded generation, decentralized generation, decentralized energy or distributed energy, generates electricity from many small energy sources....

schemes. This may in some cases include district heating

District heating

District heating is a system for distributing heat generated in a centralized location for residential and commercial heating requirements such as space heating and water heating...

, community chilled water, shared wind turbines, etc. There are current plans to use ZEB technologies to build entire off-the-grid or net zero energy use cities.

The "energy harvest" versus "energy conservation" debate

One of the key areas of debate in zero energy building design is over the balance between energy conservation

Energy conservation

Energy conservation refers to efforts made to reduce energy consumption. Energy conservation can be achieved through increased efficient energy use, in conjunction with decreased energy consumption and/or reduced consumption from conventional energy sources...

and the distributed point-of-use harvesting of renewable energy

Renewable energy

(solar energy and wind energy

Wind energy

Wind energy is the kinetic energy of air in motion; see also wind power.Total wind energy flowing through an imaginary area A during the time t is:E = ½ m v2 = ½ v 2...

). Most zero energy homes use a combination of the two strategies.

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 harvesting technologies. Entire additions of such homes have appeared in locations where photovoltaic (PV) subsidies are significant, but many so called "Zero Energy Homes" still have utility bills. This type of energy harvesting without added energy conservation may not be cost effective with the current price of electricity generated with photovoltaic equipment (depending on the local price of power company electricity), and may also requires greater embodied energy and greater resources so be thus the less ecological approach.

Since the 1980s passive solar building design

Passive solar building design

In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer...

and passive house

Passive house

The term passive house refers to the rigorous, voluntary, Passivhaus standard for energy efficiency in a building, reducing its ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling. A similar standard, MINERGIE-P, is used in...

have demonstrated heating energy consumption reductions of 70% to 90% in many locations, without active energy harvesting. For new builds, and with expert design, this can be accomplished with little additional construction cost for materials over a conventional building. Very few industry experts have the skills or experience to fully capture benefits of the passive design. Such passive solar designs are much more cost effective than adding expensive photovoltaic panels on the roof of a conventional inefficient building. A few kilowatt-hours of photovoltaic panels (costing 2 to 3 dollars per annual kW-hr production, U.S. dollar equivalent) may only reduce external energy requirements by 15% to 30%. A 100000 BTU high seasonal energy efficiency ratio

Seasonal energy efficiency ratio

The efficiency of air conditioners is often rated by the Seasonal Energy Efficiency Ratio which is defined by the Air Conditioning, Heating and Refrigeration Institute in its standard ARI 210/240, Performance Rating of Unitary Air-Conditioning and Air-Source Heat Pump Equipment.The SEER rating of...

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

Off-the-grid

The term off-the-grid or off-grid refers to living in a self-sufficient manner without reliance on one or more public utilities....

night-time operation. Passive cooling

Passive cooling

Passive cooling refers to technologies or design features used to cool buildings without power consumption, such as those technologies discussed in the Passive house project.-Passive cooling:...

, and superior system engineering techniques, can reduce the air conditioning requirement by 70% to 90%. Photovoltaic generated electricity becomes more cost-effective when the overall demand for electricity is lower.

Occupant behavior

The energy used in a building can vary greatly depending on the behavior of its occupants. The acceptance of what is considered comfortable varies widely. Studies of identical homes in the United States have shown dramatic differences in energy use, with some homes using more than twice the energy of others. Occupant behavior can vary from differences in setting and programming thermostat

Thermostat

A thermostat is the component of a control system which regulates the temperature of a system so that the system's temperature is maintained near a desired setpoint temperature. The thermostat does this by switching heating or cooling devices on or off, or regulating the flow of a heat transfer...

s, varying levels of illumination

Over-illumination

Over-illumination is the presence of lighting intensity beyond that required for a specified activity. Over-illumination was commonly ignored between 1950 and 1995, especially in office and retail environments; only since then has the interior design community begun to reconsider this practice.The...

and hot water, and the amount of miscellaneous electric devices

Miscellaneous electric load

Miscellaneous electric loads in buildings are electric loads resulting from electronic devices not responsible for space heating, cooling, water heating, or lighting...

used.

Development efforts

Wide acceptance of zero energy building technology may require more government incentives or building code regulations, the development of recognized 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 outage

Power outage

A power outage is a short- or long-term loss of the electric power to an area.There are many causes of power failures in an electricity network...

s, and air pollution

Air pollution

Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment, into the atmosphere....

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

Lafarge

Lafarge is a French industrial company specialising in four major products: cement, construction aggregates, concrete and gypsum wallboard. In 2010 the company was the world's second-largest cement manufacturer by mass shipped behind Holcim.-History:...

, 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.

Influential zero- and low-energy buildings

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

R-2000 program

R-2000 is a Natural Resources Canada program that was developed in partnership with the Canadian Home Builders' Association in 1981, and formalized as a standard in 1982...

and the German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

passive house
Passive house
The term passive house refers to the rigorous, voluntary, Passivhaus standard for energy efficiency in a building, reducing its ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling. A similar standard, MINERGIE-P, is used in...

standards have been internationally influential. Collaborative government demonstration projects, such as the superinsulated Saskatchewan House, and the International Energy Agency's

International Energy Agency

The International Energy Agency is a Paris-based autonomous intergovernmental organization established in the framework of the Organisation for Economic Co-operation and Development in 1974 in the wake of the 1973 oil crisis...

Task 13, have also played their part.

Advantages

isolation for building owners from future energy price increases
increased comfort due to more-uniform interior temperatures (this can be demonstrated with comparative isotherm maps)
reduced requirement for energy austerity
Austerity
In economics, austerity is a policy of deficit-cutting, lower spending, and a reduction in the amount of benefits and public services provided. Austerity policies are often used by governments to reduce their deficit spending while sometimes coupled with increases in taxes to pay back creditors to...
reduced total cost of ownership
Total cost of ownership
Total cost of ownership is a financial estimate whose purpose is to help consumers and enterprise managers determine direct and indirect costs of a product or system...

due to improved energy efficiency
Efficient energy use
Efficient energy use, sometimes simply called energy efficiency, is the goal of efforts to reduce the amount of energy required to provide products and services. For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature...
reduced total net monthly cost of living
improved reliability - photovoltaic systems have 25-year warranties - seldom fail during weather problems - the 1982 photovoltaic systems on the Walt Disney World EPCOT Energy Pavilion are still working fine today, after going through 3 recent hurricanes
extra cost is minimized for new construction compared to an afterthought retrofit
higher resale value as potential owners demand more ZEBs than available supply
the value of a ZEB building relative to similar conventional building should increase every time energy costs increase
future legislative restrictions, and carbon emission taxes/penalties may force expensive retrofits to inefficient buildings

Disadvantages

initial costs can be higher - effort required to understand, apply, and qualify for ZEB subsidies
very few designers or builders have the necessary skills or experience to build ZEBs
possible declines in future utility company renewable energy costs may lessen the value of capital invested in energy efficiency
new photovoltaic solar cells equipment technology price has been falling at roughly 17% per year - It will lessen the value of capital invested in a solar electric generating system - Current subsidies will be phased out as photovoltaic mass production lowers future price
challenge to recover higher initial costs on resale of building - appraisers are uninformed - their models do not consider energy
while the individual house may use an average of net zero energy over a year, it may demand energy at the time when peak demand for the grid occurs. In such a case, the capacity of the grid must still provide electricity to all loads. Therefore, a ZEB may not reduce the required power plant capacity.
without an optimised thermal envelope the embodied energy, heating and cooling energy and resource usage is higher than needed. ZEB by definition do not mandate a minimum heating and cooling performance level thus allowing oversized renewable energy systems to fill the energy gap.
solar energy capture using the house envelope only works in locations unobstructed from the South. The solar energy capture cannot be optimized in South (for northern hemisphere, or North for southern Hemisphere) facing shade or wooded surroundings.

Zero energy building versus green building

The goal of green building

Green building

Green building refers to a structure and using process that is environmentally responsible and resource-efficient throughout a building's life-cycle: from siting to design, construction, operation, maintenance, renovation, and demolition...

and sustainable architecture

Sustainable architecture

Sustainable architecture is a general term that describes environmentally conscious design techniques in the field of architecture. Sustainable architecture is framed by the larger discussion of sustainability and the pressing economic and political issues of our world...

is to use resources more efficiently and reduce a building's negative impact on the environment. Zero energy buildings achieve one key green-building goal of completely or very significantly reducing energy use and greenhouse gas

Greenhouse gas

A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

emissions for the life of the building. Zero energy buildings may or may not be considered "green" in all areas, such as reducing waste, using recycled

Recycling

Recycling is processing used materials into new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution and water pollution by reducing the need for "conventional" waste disposal, and lower greenhouse...

building materials, etc. However, zero energy, or net-zero buildings do tend to have a much lower ecological impact over the life of the building compared with other "green" buildings that require imported energy and/or fossil fuel to be habitable and meet the needs of occupants.

Because of the design challenges and sensitivity to a site that are required to efficiently meet the energy needs of a building and occupants with renewable energy (solar, wind, geothermal, etc.), designers must apply holistic design principles, and take advantage of the free naturally occurring assets available, such as passive solar orientation, natural ventilation, daylighting, thermal mass, and night time cooling.

Certification

Many Green building

Green building

certification programs do not require a building to have net zero energy use, only to reduce energy use a few percentage points below the minimum required by law. The Leadership in Energy and Environmental Design

Leadership in Energy and Environmental Design

Leadership in Energy and Environmental Design consists of a suite of rating systems for the design, construction and operation of high performance green buildings, homes and neighborhoods....

(LEED) certification developed by the U.S. Green Building Council, and Green Globes, involve check lists that are measurement tools, not design tools. Inexperienced designers or architects may cherry-pick points to meet a target certification level, even though those points may not be the best design choices for a specific building or climate.

Canada

In Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

the Net-Zero Energy Home Coalition is an industry association promoting net-zero energy home construction and the adoption of a near net-zero energy home (nNZEH), NZEH Ready and NZEH standard.
The Canada Mortgage and Housing Corporation
Canada Mortgage and Housing Corporation
Canada Mortgage and Housing Corporation is a Crown corporation, owned by the Government of Canada, founded after World War II to provide housing for returning soldiers...

is sponsoring the EQuilibrium Sustainable Housing Competition that will see the completion of fifteen zero-energy and near-zero-energy demonstration projects across the country starting in 2008.
The EcoTerra House in Eastman, Quebec is Canada's first nearly net-zero energy housing built through the CMHC EQuilibrium Sustainable Housing Competition. The house was designed by Dr. Masa Noguchi of the Mackintosh School of Architecture
Mackintosh School of Architecture
The Mackintosh School of Architecture of the University of Glasgow/Glasgow School of Art is one of the three schools which makes up the Glasgow School of Art, situated in the Garnethill area of Glasgow, Scotland. The Mackintosh School of Architecture is the GSA's only academic school concerned...

for Alouette Homes and engineered by Prof. Dr. Andreas K. Athienitis of Concordia University
Concordia University
Concordia University is a comprehensive Canadian public university located in Montreal, Quebec, one of the two universities in the city where English is the primary language of instruction...

.
The EcoPlusHome in Bathurst, New Brunswick. The Eco Plus Home is a prefabricated test house built by Maple Leaf Homes and with technology from Bosch Thermotechnology.
The first net-zero passive house in Northshore, Vancouver, BC, is designed by Dr. Homayoun Arbabian. The design and construction of this SuperEcoHouse is undertaken by Vancouver Green Homes LTD.

China

One example of the new generation of zero energy office buildings is the 71-story Pearl River Tower
Pearl River Tower
The Pearl River Tower is a clean technology skyscraper under construction at the junction of Jinsui Road/Zhujiang Avenue West, Tianhe District, Guangzhou, China. The tower's architecture and engineering were performed by Skidmore, Owings, and Merrill with Adrian D. Smith and Gordon Gill as...

, which opened in 2009, as the Guangdong Company headquarters. It uses both modest energy efficiency, and a big distributed renewable energy generation from both solar and wind. Designed by Skidmore Owings Merrill LLP in Guangzhou, China
Guangzhou
Guangzhou , known historically as Canton or Kwangchow, is the capital and largest city of the Guangdong province in the People's Republic of China. Located in southern China on the Pearl River, about north-northwest of Hong Kong, Guangzhou is a key national transportation hub and trading port...

, the tower is receiving economic support from government subsidies that are now funding many significant conventional fossil-fuel (and nuclear energy
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

) energy reduction
Energy conservation
Energy conservation refers to efforts made to reduce energy consumption. Energy conservation can be achieved through increased efficient energy use, in conjunction with decreased energy consumption and/or reduced consumption from conventional energy sources...

efforts.
Dongtan
Dongtan
Dongtan is a plan for a new eco-city on the island of Chongming in Shanghai, China. The name of the city literally translates as "East Beach".-Population:...

Eco-City near Shanghai
Shanghai
Shanghai is the largest city by population in China and the largest city proper in the world. It is one of the four province-level municipalities in the People's Republic of China, with a total population of over 23 million as of 2010...

Germany

Technische Universität Darmstadt won first place in the international zero energy design 2007 Solar Decathlon competition, with a passivhaus design (Passive house
Passive house
The term passive house refers to the rigorous, voluntary, Passivhaus standard for energy efficiency in a building, reducing its ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling. A similar standard, MINERGIE-P, is used in...

) + renewables, scoring highest in the Architecture, Lighting, and Engineering contests
Fraunhofer Institute for Solar Energy Systems (ISE), Freiburg im Breisgau

Iran

In 2011 Energy Payesh House (EPH) or Khaneh Niroo Payesh by a collaboration of Fajr-e-Toseah Consultant Engineering Company and ancouver Green Homes Ltd] under management of Energy Payesh Group (EPG) launched the first Net-Zero passive house in Iran. This concept makes the design and construction of EPhouse a sample model and standardized process for mass production by MAPSA.

Also an example of the new generation of zero energy office buildings is the 24-story OIIC Office Tower, which is started in 2011, as the OIIC Company headquarter. It uses both modest energy efficiency, and a big distributed renewable energy generation from both solar and wind. It is managed by Rahgostar Naft Company and advised by Dr. Homayoun Arbabian (CEA) in Tehran, Iran. The tower is receiving economic support from government subsidies that are now funding many significant fossil-fuel-free efforts.

Ireland

In 2005 Scandinavian Homes launched the worlds first standardised passive house in Ireland, this concept makes the design and construction of passive house a standardised process.
Conventional low energy construction techniques have been refined and modelled on the PHPP (Passive House Design Package) to create the standardised passive house.
Building offsite allows high precision techniques to be utilised and reduces the possibility of errors in construction.

In 2009 the same company started a project to use 23,000 liters of water in a seasonal storage tank, heated up by evacuated solar tubes throughout the year, with the aim to provide the house with enough heat throughout the winter months thus eliminating the need for any electrical heat to keep the house comfortably warm. The system is monitored and documented by a research team from The University of Ulster and the results will be included in part of a PhD

PHD

PHD may refer to:*Ph.D., a doctorate of philosophy*Ph.D. , a 1980s British group*PHD finger, a protein sequence*PHD Mountain Software, an outdoor clothing and equipment company*PhD Docbook renderer, an XML renderer...

thesis.

Malaysia

In October 2007, the Malaysia Energy Centre (PTM) successfully completed the development and construction of the PTM Zero Energy Office (ZEO) Building. The building has been designed to be a super-energy-efficient building using only 286 kW·h/day. The renewable energy - photovoltaic combination is expected to result in a net zero energy requirement from the grid. The building is currently undergoing a fine tuning process by the local energy management team. Findings are expected to be published in a year.

the Netherlands

In September 2006, the Dutch headquarters of the World Wildlife Fund (WWF) in Zeist

Zeist

Zeist is a municipality and a town in the central Netherlands, located east of the city of Utrecht.-Population centres :*Austerlitz*Bosch en Duin*Den Dolder*Huis ter Heide*Zeist- The town of Zeist :...

was opened. This earth-friendly building, gives back more energy than it uses. All materials in the building were tested against strict requirements laid down by the WWF and the architect.

Norway

In February 2009, the Research Council of Norway

Norway

Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

assigned The Faculty of Architecture and Fine Art at the Norwegian University of Science and Technology to host the Research Centre on Zero Emission Buildings (ZEB), which is one of eight new national Centres for Environment-friendly Energy Research (FME). The main objective of the FME-centres is to contribute to the development of good technologies for environmentally friendly energy and to raise the level of Norwegian expertise in this area. In addition, they should help to generate new industrial activity and new jobs. Over the next eight years, the FME-Centre ZEB will develop competitive products and solutions for existing and new buildings that will lead to market penetration of zero emission buildings related to their production, operation and demolition.

Singapore

Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...

's first zero energy building was launched at the inaugural Singapore Green Building Week.

Switzerland

The Swiss MINERGIE

Minergie

MINERGIE is a registered quality label for new and refurbished low-energy-consumption buildings. This label is mutually supported by the Swiss Confederation, the Swiss Cantons and the Principality of Liechtenstein along with Trade and Industry. The label is registered in Switzerland and around the...

-A-Eco label certifies zero energy buildings. The first building with this label, a single-family home, was completed in Mühleberg

Mühleberg

Mühleberg is a municipality in the Bern-Mittelland administrative district in the canton of Bern in Switzerland.-Geography:Mühleberg has an area of . Of this area, 53.6% is used for agricultural purposes, while 32.9% is forested...

in 2011.

United Kingdom

In December 2006 the government announced that by 2016 all new homes in England will be zero energy buildings. To encourage this, an exemption from Stamp Duty Land Tax is planned. In Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

the plan is for the standard to be met earlier in 2011, although it is looking more likely that the actual implementation date will be 2012. However, as a result of a unilateral change of policy published at the time of the March 2011 budget, a more limited policy is now planned which, it is estimated, will only mitigate two thirds of the emissions of a new home.

BedZED
BedZED
Beddington Zero Energy Development is an environmentally friendly housing development in Hackbridge, London, England. It is in the London Borough of Sutton. It was designed by the architect Bill Dunster to support a more sustainable lifestyle...

development
Hockerton Housing Project Hockerton Housing Project

United States

In the US

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, ZEB research is currently being supported by the US Department of Energy (DOE) Building America Program , including industry-based consortia and researcher organizations at the National Renewable Energy Laboratory

National Renewable Energy Laboratory

The National Renewable Energy Laboratory , located in Golden, Colorado, is the United States' primary laboratory for renewable energy and energy efficiency research and development. The National Renewable Energy Laboratory is a government-owned, contractor-operated facility; it is funded through...

(NREL), the Florida Solar Energy Center

Florida Solar Energy Center

The Florida Solar Energy Center is a research institute of the University of Central Florida, located on a 20 acre research complex on Florida's Space Coast at UCF's Cocoa satellite campus. FSEC is the largest and most active state-supported renewable energy and energy efficiency research,...

(FSEC), Lawrence Berkeley National Laboratory

Lawrence Berkeley National Laboratory

The Lawrence Berkeley National Laboratory , is a U.S. Department of Energy national laboratory conducting unclassified scientific research. It is located on the grounds of the University of California, Berkeley, in the Berkeley Hills above the central campus...

(LBNL), and Oak Ridge National Laboratory

Oak Ridge National Laboratory

Oak Ridge National Laboratory is a multiprogram science and technology national laboratory managed for the United States Department of Energy by UT-Battelle. ORNL is the DOE's largest science and energy laboratory. ORNL is located in Oak Ridge, Tennessee, near Knoxville...

(ORNL). From fiscal year 2008 to 2012, DOE plans to award $40 million to four Building America teams, the Building Science Corporation; IBACOS; the Consortium of Advanced Residential Buildings; and the Building Industry Research Alliance, as well as a consortium of academic and building industry leaders. The funds will be used to develop net-zero-energy homes that consume at 50% to 70% less energy than conventional homes.

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

Efficient energy use

Efficient energy use, sometimes simply called energy efficiency, is the goal of efforts to reduce the amount of energy required to provide products and services. For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature...

technologies. The two centers, located at the University of Central Florida

University of Central Florida

The University of Central Florida, commonly referred to as UCF, is a metropolitan public research university located in Orlando, Florida, United States...

and Washington State University

Washington State University

Washington State University is a public research university based in Pullman, Washington, in the Palouse region of the Pacific Northwest. Founded in 1890, WSU is the state's original and largest land-grant university...

, will serve 17 states, providing information and training on commercially available energy-efficient technologies.

The U.S. Energy Independence and Security Act of 2007

Energy Independence and Security Act of 2007

The Energy Independence and Security Act of 2007 is an Act of Congress concerning the energy policy of the United States...

created 2008 through 2012 funding for a new solar air conditioning

Solar air conditioning

Solar air conditioning refers to any air conditioning system that uses solar power.This can be done through passive solar, solar thermal energy conversion and photovoltaic conversion . The U.S...

research and development program, which should soon demonstrate multiple new technology innovations and mass production

Mass production

Mass production is the production of large amounts of standardized products, including and especially on assembly lines...

economies of scale

Economies of scale

Economies of scale, in microeconomics, refers to the cost advantages that an enterprise obtains due to expansion. There are factors that cause a producer’s average cost per unit to fall as the scale of output is increased. "Economies of scale" is a long run concept and refers to reductions in unit...

.

The 2008 Solar America Initiative funded research and development into future development of cost-effective Zero Energy Homes in the amount of $148 million in 2008.

The Solar Energy Tax Credits have been extended until the end of 2016. Solar power in the United States

Solar power in the United States

Solar power in the United States is an area of considerable activity and there are many utility-scale solar power plants. The largest solar power installation in the world is the Solar Energy Generating Systems facility in California, which has a total capacity of 354 megawatts...

By Executive Order 13514, U.S. President Barack Obama mandated that by 2015, 15% of existing Federal buildings conform to new energy efficiency standards and 100% of all new Federal buildings be Zero-Net-Energy

Zero-Net-Energy USA Federal Buildings

A Zero-Net-Energy Building is an official designation in the United States for a building whose construction and operation creates zero net emissions of greenhouse gases, as specified in President Obama's Executive Order 13514 of October 5, 2009....

by 2030.

Energy Free Home Challenge - In 2007, the philanthropic Siebel Foundation created the Energy Free Home Foundation. The goal was to offer $20 million in global incentive prizes to design and build a 2,000 square foot (186 square meter) three-bedroom, two bathroom home with (1) net-zero annual utility bills that also has (2) high market appeal, and (3) costs no more than a conventional home to construct.

The plan included funding to build the top ten entries at $250,000 each, a $10 million first prize, and then a total of 100 such homes to be built and sold to the public.

Beginning in 2009, Thomas Siebel

Thomas Siebel

Thomas Siebel is a business executive. He is the chairman of First Virtual Group, a diversified holding company with interests in commercial real estate, agribusiness, global investment management, and philanthropy.-Education and Work:...

made many presentations about his Energy Free Home Challenge. The Siebel Foundation Report stated that the Energy Free Home Challenge was "Launching in late 2009".

Berkley National Laboratory (University of California, Berkley) participated in writing the "Feasibility of Achieving Zero-Net-Energy, Zero-Net-Cost Homes" for the $20-million Energy Free Home Challenge.

Although the energyfreehome.org website is still defined, everything about the $20-million Challenge has been deleted without explanation.

If implemented, the Energy Free Home Challenge would have provided much-needed increased incentives for improved technology and consumer education about zero energy building at the same cost as conventional housing.
Arizona

Zero Energy House developed by the NAHB Research Center and John Wesley Miller Companies, Tucson.

California

The IDeAs Z2 Design Facility is a net zero energy, zero carbon retrofit project occupied since 2007. It uses less than one fourth the energy of a typical U.S. office by applying strategies such as daylighting, radiant heating/cooling with a ground-source heat pump and high energy performance lighting and computing. The remaining energy demand is met with renewable energy from its building-integrated photovoltaic array. In 2009, building owner and occupant Integrated Design Associates (IDeAs) recorded actual measured energy use intensity of 21.17 kbtu/sf-year, with 21.72 kbtu/sf-year produced, for a net of -0.55 kbtu/sf-yr. The building is also carbon neutral, with no gas connection, and with carbon offset
Carbon offset
A carbon offset is a reduction in emissions of carbon dioxide or greenhouse gases made in order to compensate for or to offset an emission made elsewhere....

s purchased to cover the embodied carbon of the building materials used in the renovation.

Florida

The 1999 side-by-side Florida Solar Energy Center
Florida Solar Energy Center
The Florida Solar Energy Center is a research institute of the University of Central Florida, located on a 20 acre research complex on Florida's Space Coast at UCF's Cocoa satellite campus. FSEC is the largest and most active state-supported renewable energy and energy efficiency research,...

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.

Michigan

The Mission Zero House is the 110-year-old Ann Arbor home of Greenovation.TV host and Environment Report contributor Matthew Grocoff
The Environment Report
The Environment Report is a show produced and syndicated by Michigan Radio in Ann Arbor, Michigan.-Mission:The Environment Report's mission is to be a news service committed to revealing the relationship between the natural world and the everyday lives of people.-1993-2006: Great Lakes Radio...

. As of 2011, the home is the oldest home in America to achieve net-zero energy. The owners are chronicling their project on Greenovation.TV and the Environment Report
The Environment Report
The Environment Report is a show produced and syndicated by Michigan Radio in Ann Arbor, Michigan.-Mission:The Environment Report's mission is to be a news service committed to revealing the relationship between the natural world and the everyday lives of people.-1993-2006: Great Lakes Radio...

on public radio.

The Vineyard Project is a Zero Energy Home (ZEH) thanks to the Passive Solar Design, 3.3 Kws of Photovoltaics,Solar Hot Water and Geothermal Heating and Cooling. The home is pre-wired for a future wind turbine and only uses 600kwh of energy per month while a minimum of 20 kWh of electricity per day with many days net-metering backwards. The project also used ICF insulation throughout the entire house and is certified as Platinum under the LEED for Homes certification. This Project was awarded Green Builder Magazine Home of the Year 2009

Missouri

In 2010, architectural firm HOK
Hellmuth, Obata and Kassabaum
HOK is a global architecture, interiors, engineering, planning and consulting firm. HOK is the largest U.S.-based architecture-engineering firm and the "No. 1 role model for sustainable and high-performance design." HOK also is the second-largest interior design firm...

worked with energy and daylighting consultant The Weidt Group to design a 170735 square feet (15,861.8 m²) net zero carbon emissions Class A office building prototype in St. Louis, Missouri
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...

. The team chronicled its process and results on Netzerocourt.com.

New Jersey

The 31 Tannery Project
31 Tannery Project
The 31 Tannery Project, located in Branchburg, New Jersey, serves as the corporate headquarters for Ferreira Construction, the Ferreira Group, and Noveda Technologies. The office and shop building was constructed in 2006 and is the 1st building in the state of New Jersey to meet...

, located in Branchburg, New Jersey, serves as the corporate headquarters for Ferreira Construction, the Ferreira Group, and Noveda Technologies. The 42,000-square-foot (3,900 m²) office and shop building was constructed in 2006 and is the 1st building in the state of New Jersey to meet New Jersey's Executive Order 54. The building is also the first Net Zero Electric Commercial Building in the United States.

New York

Green Acres, the first true zero-net energy development in America, is located in New Paltz, about 80 miles (128.7 km) north of New York City. Greenhill Contracting began construction on this development of 25 single family homes in summer 2008, with designs by BOLDER Architecture. After a full year of occupancy, from March 2009 to March 2010, the solar panels of the first occupied home in Green Acres generated 1490 kWh more energy than the home consumed. The chart of energy use and production is available at http://www.greenacresnewpaltz.com/pages/performance.html. The second occupied home has also achieved zero-net energy use. As of June 2011, 5 houses have been completed, purchased and occupied, 2 are under construction, and several more are being planned. The homes are built of insulated concrete forms with spray foam insulated
Spray foams (insulation)
Spray foam insulation is an alternative to traditional building insulation such as fiberglass. A two-component mixture comes together at the tip of a gun, and forms an expanding foam that is sprayed onto roof tiles,concrete slabs, into wall cavities, or through holes drilled in into a cavity of a...

rafters and triple pane casement windows, heated and cooled by a geothermal system, to create extremely energy-efficient and long-lasting buildings. The heat recovery ventilator provides constant fresh air and, with low or no VOC
Volatile organic compound
Volatile organic compounds are organic chemicals that have a high vapor pressure at ordinary, room-temperature conditions. Their high vapor pressure results from a low boiling point, which causes large numbers of molecules to evaporate or sublimate from the liquid or solid form of the compound and...

(volatile organic compound) materials, these homes are very healthy to live in. To the best of our knowledge, Green Acres is the first development of multiple buildings, residential or commercial, that achieves true zero-net energy use in the United States, and the first zero-net energy development of single family homes in the world.

Greenhill Contracting has built 2 luxury zero-net energy homes in Esopus, completed in 2008. One house was the first Energy Star rated zero-net energy home in the Northeast and the first registered zero-net energy home on the US Department of Energy's Builder's Challenge website. These homes were the template for Green Acres and the other zero-net energy homes that Greenhill Contracting has built, in terms of methods and materials.

The headquarters of Hudson Valley Clean Energy, located in Rhinebeck and completed in 2007, is the first and only zero-net energy, carbon-free commercial building in New York State and the entire Northeast. The building consumes less energy than it generates, using a solar electric system to generate power from the sun, geothermal heating and cooling, and solar thermal collectors to heat all its hot water.

Oklahoma

The first 5000 square feet (464.5 m²) zero energy design home was built in 1979 with support from President Carter's new United States Department of Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...

. It relied heavily on passive solar building design
Passive solar building design
In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer...

for space heat, water heat and space cooling. It heated and cooled itself effectively in a climate where the summer peak temperature was 110 degrees Fahrenheit, and the winter low temperature was -10 F. It did not use active solar
Active solar
Active solar technologies are employed to convert solar energy into another more useful form of energy. This would normally be a conversion to heat or electrical energy. Inside a building this energy would be used for heating, cooling, or off-setting other energy use or costs. Active solar uses...

systems. It is a double envelope house
Double envelope house
-History:Lee Porter Butler's 1975 Double Envelope design received wide publicity after the U.S. solar energy tax credits were created in 1978. Versions were on the cover of Better Homes and Gardens and Popular Science magazines....

that uses a gravity-fed natural convection
Natural convection
Natural convection is a mechanism, or type of heat transport, in which the fluid motion is not generated by any external source but only by density differences in the fluid occurring due to temperature gradients. In natural convection, fluid surrounding a heat source receives heat, becomes less...

air flow design to circulate passive solar heat from 1000 square feet (92.9 m²) of south-facing glass on its greenhouse
Greenhouse
A greenhouse is a building in which plants are grown. These structures range in size from small sheds to very large buildings...

through a thermal buffer zone in the winter. A swimming pool in the greenhouse provided thermal mass for winter heat storage. In the summer, air from two 24 inches (609.6 mm) 100 feet (30.5 m)-long underground earth tubes is used to cool the thermal buffer zone and exhaust heat through 7200 cfm of outer-envelope roof vents.

Texas

The University of North Texas (UNT) is currently constructing a Zero Energy Research Laboratory on its 300 acre research campus, Discovery Park, in Denton, Texas. The project is funded at over $1,150,000 and will primarily benefit students in mechanical and energy engineering (UNT became the first university to offer degrees in mechanical and energy engineering in 2006). This 1,200 square-foot structure is expected to open in early 2012.

Vermont

The Putney School's net zero Field House was opened October 10, 2009. In use for a over a year, as of December, 2010, the Field House used 48,374 kWh and produced a total of 51,371 kWh during the first 12 months of operation, thus performing at slightly better than net-zero. Also in December, the building won an AIA-Vermont Honor Award.
The Charlotte Vermont House designed by Pill-Maharam Architects is a verified net zero energy house completed in 2007. The project won the Northeast Sustainable Energy Association's Net Zero Energy award in 2009.

External links

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

Modern evolution

Definitions

Design and construction

Energy harvest

The "energy harvest" versus "energy conservation" debate

Occupant behavior

Development efforts

Influential zero- and low-energy buildings

Advantages

Disadvantages

Zero energy building versus green building

Certification

Canada

China

Germany

Iran

Ireland

Malaysia

the Netherlands

Norway

Singapore

Switzerland

United Kingdom

United States

See also

Further reading

External links