The basic theory of green building is very simple: any building construction should be done in a way that supports the natural cycle of life and its systems. Although it is almost impossible for human beings to live and work without having some negative effects on the environment, green building strives to minimize that impact as much as possible by using processes, designs, and products that do not deplete resources, disturb ecosystems, or disrupt natural life rhythms. Some green building practices seek to have a positive impact on the environment by contributing to regenerating resources. Green design is sensitive not only to the environment, but to the life rhythms of the people who will live or work in a building. It aims to maximize comfort and provide sunlight, fresh air, and protection from pollution and noise.
The concept is simple, but the practice of green building can become complicated. Green building encompasses three objectives: energy efficiency, conserving resources, and creating a healthy indoor environment for the building occupants. In practice, these objectives sometimes counteract each other; for example, a highly energy-efficient air conditioning system might contain components that cannot be recycled when the system ceases to function. Some trade-offs are inevitable in selecting materials and technologies for a green project. The choices that must be made are unique to each green building project because they are determined by many factors, including climate and geographical location, the physical characteristics of the building site, local availability of building materials and trained professionals, the needs of the building occupants, and the personality and financial resources of the builder.
Energy efficiency: A well-designed green home uses as little energy as possible to maintain the comfort of its occupants. Renewable energy is used whenever possible. Energy efficiency not only saves on utility bills, but it also reduces greenhouse gas emissions and air pollution because less fossil fuel is burned.
Conservation of resources: Conventional construction consumes large amounts of water, wood, cement, metal, and plastics. Using alternative building materials made of recycled or renewable content, and more durable components that do not have to be replaced, reduces waste. Green homes use fixtures and appliances such as low-flow showerheads, faucets, and toilets and ENERGY STAR dishwashers and washing machines to conserve water. Low-volume irrigation systems, rainwater collection systems, wastewater treatment systems, and hot water recirculation systems also save water. Traditional suburban lawns consume excessive amounts of precious water and fertilizer and displace native species. “Green” landscaping preserves habitat, incorporates native plants, and uses less water.
Durability: Many conventional homes are built with products that will not last a long time, such as shingle roofs that must be replaced every 12 to 25 years. Faulty construction and inattention to detail lead to moisture leaks that cause premature deterioration of walls and sidings. Green homes are built to last and are easy to maintain and repair.
Indoor air quality: The air inside a home often contains spores and allergens from mold and mildew caused by water leaks and poorly designed heating and air conditioning systems; dust and particles from air ducts; polluted air drawn into the house from outside or from a garage or basement; and toxic chemicals given off by paints, adhesives, and cleaning products. Toxins including lead, radon, asbestos, and pesticides also contribute to poor indoor air quality. Green building uses nontoxic, low-emitting products, creates an airtight barrier between the interior of a building and the outdoors, and closely monitors the design and performance of ventilation, heating, and cooling systems.
Green building is also called “sustainable building” and “high-performance building” because it aims to be as efficient as possible from design until the building is demolished (in green building, the term is deconstructed) and its remnants are disposed of. Sustainability and high performance translate into lower costs, with the result that some green building practices are now becoming standard for conventional builders.
Conventional building design typically considers only the environmental impact of the finished structure. Green building takes a much wider view and calculates the effect every activity associated with a building has on the environment. Green building considers the impact of new land development on the community, the energy and resources used to manufacture and transport building materials to the site, energy and water use in the building, disposal of waste products, how the building materials and components can be eventually salvaged and reused, and even the pollution generated when occupants of the house drive to work, school, and shopping.
Green Building Concepts
Green building is not just a technique; it is guided by a philosophy that defines the green aspects of a building during design, construction, occupation of the building, and ultimately its deconstruction. The terminology used in green building may seem unfamiliar if you have never been involved in a green building project before. Here are some of the basic concepts of green building:
Sustainability
A primary goal of green building is sustainability — using available resources in a way that does not deplete them for future generations and allows their use to continue indefinitely. Green building uses processes, designs, and products that do not deplete natural resources and, in some cases, that actively contribute to regenerating resources. A sustainable building minimizes its water and energy use, improves the quality of life for its occupants and the community, cuts down on waste, and does not contribute significantly to the depletion of natural resources throughout the entire life of the building.
The terms “sustainable building” and “green building” are often used interchangeably. Sometimes “green building” is used to refer to buildings constructed for environmental reasons, and “sustainable building” to refer to those that are constructed to conserve costs and energy.
Energy efficiency
Energy-efficient design uses the least possible amount of energy to get the desired result. For example, south-facing windows that allow sunlight to warm the interior of a building but prevent heat from escaping will reduce the need for heating in the winter. Natural air circulation helps to cool a building in summer.
A building can be made more energy efficient by using insulation to help maintain the temperature inside the building: sealing cracks and air leaks and using materials that do not conduct heat and cold for window frames. In hot climates, materials that reflect or re-emit absorbed heat are used on roofs and exteriors to keep the interior of buildings cooler.
The amount of energy needed to heat or cool a building can be reduced by using a geothermal system and by installing devices that transfer heat or cold from outgoing air to incoming air.
An energy-efficient product or appliance uses less energy than a conventional product but provides the same service. For example, energy-efficient window air conditioners use about 10 percent less energy than conventional air conditioners but still provide the same quality and level of cooling.
Products that earn the ENERGY STAR® rating prevent greenhouse gas emissions by meeting strict energy efficiency guidelines set by the U.S. Environmental Protection Agency and the U.S. Department of Energy.
ENERGY STAR, a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy, assigns energy performance ratings to buildings and appliances. A building or an appliance that meets EPA energy efficiency requirements is given an ENERGY STAR rating to let consumers know that they are saving resources when they purchase it.
Renewable resources
A renewable resource can be replenished naturally at a rate that is greater than the rate at which it is consumed. Wind and solar power are considered renewable sources of energy because wind and sunshine are abundant and natural, and energy from these sources is easily accessible and has the potential to be replenished at a faster rate than it is consumed. Bamboo is considered a renewable building material because it grows rapidly; it reaches a mature height of 75 feet in two months, and its cultivation does not require using pesticides.
Environmentally friendly/ eco-friendly materials and practices
The terms environmentally friendly and eco-friendly refer to products, materials, buildings, and practices that cause little or no harm to the environment and only minimally interfere with natural ecosystems. Straw bales, which are blocks of wheat, rice, oats, and other grain stalks, are an example of an eco-friendly building material because these natural materials from leftover agriculture do not require using non-renewable resources for production. Building materials made with recycled content or waste products, such as concrete made with fly ash from coal-fired power plants, and materials that are completely recyclable or biodegradable when they are no longer needed are considered eco-friendly.
Ecological design
Ecological design uses systems compatible with nature and modeled on natural systems to synergize with the surrounding environment and minimize damage to the landscape. Most conventional buildings are modeled after machines rather than nature and are designed to conform to industrial processes. Ecological design is sometimes referred to as “green design.”
Ecologically designed waterfront apartments.
Ecological design faces a number of problems, including a dearth of knowledge about how to apply ecology to design. Ecologists understand ecology in different ways; some focus on energy usage while others focus on management processes. Building professionals typically have only a shallow understanding of ecology and follow a long tradition of machine-oriented design. Many natural processes, such as the growth of trees and the decomposition of materials, occur over periods of time that exceed a human lifespan, while man-made processes occur rapidly and at will.
Embodied energy
Raw natural resources, such as limestone, clay, iron ore, sand, gypsum, wood fiber, resins, coal, and petroleum products, are used in building a home. Energy in the form of electricity, diesel fuel, gasoline, wood, coal, or nuclear power is used to manufacture finished products out of these raw materials and construct a house. The cumulative impact of using all these natural resources and energy is not immediately apparent. Embodied energy refers to the total amount of energy expended in acquiring and processing raw materials, transporting them to the building site, and installing them in a building. Products with greater embodied energy typically have a greater environmental impact because of emissions from the fossil fuels used to process and transport them. A highly durable product, though, has less environmental impact when you consider that it can remain in use for longer periods than another less durable material with less embodied energy. Also, some products have a much lower embodied energy when they are recycled, which makes them more environmentally sound than a product with less embodied energy that cannot be recycled. Scientific studies of embodied energy have produced databases and software programs that calculate the embodied energy of individual materials and entire buildings. It is sometimes difficult to compare the embodied energy of two similar building materials because there is no accepted worldwide standard or method, but embodied energy should never be ignored when selecting materials for building.
Life cycle
The life cycle of a product, building, or material encompasses every phase of its existence, from its initial creation to its destruction. In green building, cost and sustainability are calculated over the life cycle of a building or material, not just when it is built or purchased. The life cycle of wood floors would include harvesting wood from a forest, manufacturing the wood into a usable product, transportation to the job site, installation, use and maintenance of the product, and ultimately, the disposal of the product when the building is demolished or the flooring is replaced.
Recyclable materials
Recyclable materials are made of various kinds of metal, plastics, glass, paper, or fibers that can be broken down and reused to manufacture a new product — ideally a new version of the same material. Recycling eliminates using energy and resources to create brand new materials and prevents tons of waste from going into landfills. Asphalt is one of the most recyclable construction materials available. Many forms of paper, metal, plastic, and glass are also easily recycled. Whether a material can be recycled is an important factor in determining the greenness of a particular building material.
Reclaimed materials
Reclaimed materials include discarded materials that can be salvaged and used in a new way. Wood from old furniture and buildings can be reused to create new furniture and buildings. Reclaimed materials differ from recycled materials in that they have not been re-processed and made into a new product, but can be used in their original form for another purpose.
Big Dig House, SsD (www.ssdarchitecture.com/works/residential/big-dig-house)
When a portion of Highway I-93 was dismantled for Boston’s Big Dig project, civil engineer Paul Pedini thought the steel and concrete should be recycled instead of being thrown away. The result was the 4,300-square foot Big Dig House in Lexington, Massachusetts. The home was constructed using 600,000 pounds of steel and concrete from the highway plus some new materials. The floors and roof are made of concrete slabs, each about 40 feet long and weighing up to 25 tons. The engineering and design firm Single Speed Design saved time and money by using most of the salvaged materials from the Big Dig in the condition in which they were found. The frame was erected in about three days. The materials are capable of carrying much higher loads than an average building, which allowed for an extensive roof garden watered with captured rainwater. Windows placed high in the walls allow light to enter deep into the interior, and strategic overhangs shade the windows from intense summer sunlight. The exterior is covered with cedar siding and glass that leaves the steel tubes and beams exposed. The house cost $645,000 to build and saved $20,000 in demolition and dumping costs. As a prototype, the house demonstrates how obsolete roadways could be dismantled and used to construct schools and other public buildings.
Closed loop material cycle
Closed-loop material cycle (CLMC) refers to a construction project employing materials and building elements that can later be recovered and infinitely recycled through natural or industrial processes. Today, much of the debris from demolished buildings ends up in landfills, even though it contains some elements that could potentially be reused. One goal of the green building movement is to develop building materials that can be completely recycled when the building reaches the end of its life.
Deconstructability
The concept of deconstructability is taking hold not only in the building industry, but also in auto and electronics manufacturing. In deconstructability, the goal is to make a product using components that can be removed and reused when the product becomes broken or obsolete. Instead of exploding an unwanted structure or smashing it with a wrecking ball, the building is dismantled piece by piece, and its components are salvaged for reuse in another building or recycled into another product.
Collaborative design
In conventional building, the architect creates a design and then contractors, plumbers, and electricians follow the plans. In green building, the construction team is part of the design process and everyone affected by the project has input from the beginning. All team members combine their expertise to design systems that interact. This maximizes design efficiency and also prevents delays and extra expense when changes have to be made during construction.
Misconceptions About Green Building
The green building industry has expanded and received considerable attention in the media. Though studies have confirmed that green building is environmentally sound and financially viable, critics continue to voice misgivings. Some of the critics’ concerns are legitimate, but a number of misconceptions continue to influence the attitude of the public. Some common misconceptions are:
Green building is for environmentalists.
Though environmentalists are advocates for green building, many of the benefits of green building appeal to everyone. Who would not be interested in saving money on utility bills and in living in a low-maintenance home where the air is free of toxins, allergens, and dust? In most communities, a green home brings a higher price on the real estate market.
Green building costs more.
In conventional building, costs are calculated in terms of initial (upfront) investment in materials and construction. Green building considers the life cycle of each product, material, and process that goes into the building’s construction and operation. Although some green materials do cost more than conventional items — for instance, natural wool carpeting is more expensive than conventional synthetic carpeting — the cost of many green building materials is comparable to the cost of conventional materials. Manufacturers of building materials are responding to the demand for environmentally responsible products by bringing down their cost.
A green project design considers the long-term budget for operating and maintaining a building, as well as the initial cost of construction. Today, the initial cost of construction materials, permits, certification, and consultation is slightly more expensive for a green building than for a conventional building. However, using sustainable and durable building materials decreases maintenance costs over the lifetime of the home and will probably pay for the larger initial investment many times over. Over the lifetime of a building, the savings realized by installing rainwater systems and energy-efficient systems such as solar panels or wind turbines outweigh the costs of implementing them.
Vendors of green building products typically quote a payback period — the number of months or years it will take for the savings realized by the product to pay for its initial cost. The payback period for many green technologies, such as solar panels, insulation upgrades, and energy-efficient air conditioners, is shortened substantially by federal and state tax deductions.
Green building is too involved.
Green building can seem intimidating to someone who is unfamiliar with it. Green building designs, terminology, and ways of thinking about material usage deviate sharply from concepts of conventional building. In fact, the basic principle of green building is simple: seek a cleaner and more energy-efficient environment both inside and outside the building. Architects, consultants, and contractors who specialize in green building can help you learn about the process.
If a building cannot conserve energy, it cannot be green.
Energy conservation is only one aspect of being green. If budget restrictions inhibit installing energy saving systems such as solar or wind power, there are many other things builders can do to make a home greener. For example, installing bamboo flooring or formaldehyde-free countertops is considered a green practice but has little to do with energy conservation.
Green buildings are always made from recycled material.
Greenness is not determined solely by the extent to which recycled materials are used. Not all building materials are recyclable, and using only material that has been recycled for a building would be almost impossible. Green building involves many factors, such as orienting your house to best use of solar energy and considering the sustainability of the overall building design. In cases where the recycling process requires a lot of energy or transporting materials over long distances, using a new building material may prove to be greener than using a recycled one.
Green buildings are ugly.
Many people believe that green buildings look ultra-modern, plain, and futuristic, but green buildings can also mirror conventional building designs. Architects and engineers can tailor a building design to meet just about any expectation. Green building features such as natural wool carpets, polished concrete floors, and recycled glass are beautiful in themselves.
There is nothing wrong with conventional building materials and processes.
Many conventional building components have harmful environmental and health effects. Commonly used paints contain high levels of volatile organic compounds (VOCs) that are given off into the air for months and even years. Most trim moldings and wood floors are coated with a chemical sealant that is hazardous to health. Vinyl tiles can emit harmful dioxins long after they are installed, and some conventional countertops, wood products, and carpets are soaked in formaldehyde, a chemical proven to be hazardous to the environment, people, and animals.
The Evolution of Green Building
Anasazi Indian dwellings in Bandelier National monument.
Some green building practices are thousands of years old. Ancient builders used natural building materials to create comfortable and energy-efficient structures that were adapted to local climates. The Anasazi Indians, who inhabited what is now Arizona, Utah, Colorado, and New Mexico about 2,000 years ago, positioned their homes and villages to optimize natural light and heat from the sun. Their homes were built in tightly knit communities so that resources could be shared. The Anasazi captured rainwater and built using resources found in the immediate area, such as mud, earth bricks, sand, and wood. Ancient Romans positioned their bathhouse windows to face the sun and benefit from its warmth, and the Greeks positioned their dwellings to absorb the sun’s warmth. Many of these characteristics have become principles of modern green building: design that makes the most of natural light and warmth; using local building materials; and community planning that minimizes environmental impact.
Rise of environmentalism
Human beings have negatively affected the environment for thousands of years as they cleared forests for agriculture, abandoned arable land after all the nutrients had been leached out of it, overhunted and overgrazed, started forest fires, and in some cases built large cities that depleted water supplies. The Industrial Revolution, which began with the establishment of the first large factories during the second half of the 18th century, rapidly accelerated the impact of human activity. For a century and a half, the opportunity for growth seemed limitless as one new technology led to another, transportation became more efficient, buildings became taller, and cities grew larger. There was a general attitude that wilderness existed to be conquered and developed and that progress could be measured by growth in the number of cities and factories.
During the second half of the 19th century, social activists in the United States and Europe began to agitate against unhealthy working and living conditions in cities and industrial areas, and laws were passed to protect workers and to ensure clean drinking water and adequate sanitation. In the United States where timber barons had made fortunes cutting down large tracts of forest and selling the wood, a few conservationists began to speak out about the need to preserve wilderness areas. Ralph Waldo Emerson and Henry David Thoreau wrote about the appreciation of nature. In 1851, a California businessman named George Gale inadvertently drew international media attention to the issue of conservation when he cut down a 2,500-year-old sequoia tree known as “Mother of the Forest” in order to display a section of its bark in a traveling sideshow. The ensuing public outrage resulted in the establishment of the first federal state park in Yosemite Valley in 1864, followed by Yellowstone National Park eight years later. In 1892, Henry Senger, Warren Olney, and John Muir established the Sierra Club to promote the preservation of wilderness areas. Today, the Sierra Club strives, “to practice and promote the responsible use of the earth’s ecosystems and resources.”
The Forest Reserve Act of 1891 established a U.S. Forest Service and gave the president authority to designate forested public lands as protected areas. During his term in office, Theodore Roosevelt increased federal land reserves to almost 200 million acres and established federal control over the building of dams and irrigation projects. In 1916, The National Park Service Organic Act established a National Park Service in the United States.
The introduction of affordable automobiles and electric power caused energy use in the United States to jump from 100 million Btu per person at end of 19th century to 214 million Btu per person in 1949. A Btu (British thermal unit) is the amount of heat required to raise 1 pound of water 1 degree Fahrenheit at one atmosphere pressure, equal to 251.997 calories.
Energy consumption increased steadily to a peak of 359 million BTU per person in 1978 and 1979. In 2009, the U.S. consumed 308 million Btu of energy per person, 44 percent above the 1949 rate. In 2009, total U.S. energy consumption was 94,578,267 billion Btu; 7,743,759 billion Btu of that was from renewable energy sources.
During the era of prosperity that followed the Great Depression and World War II, suburbs and urban sprawl arose around U.S. cities. Fertilizers and pesticides came into widespread use, and air conditioning made it possible to live and work comfortably even in hot and humid climates. However, there were alarming signs of an environmental crisis. A suffocating blanket of smog covered Los Angeles (1954); in 1952 a “London fog” killed 4,000 people in four days; in 1948 an atmospheric inversion in which high temperatures in the upper atmosphere prevented cooler, polluted air on the ground from circulating temporarily raised the death rate in Donora, Pennsylvania, by 400 percent; in 1953, smog killed between 170 and 260 people in New York. In response, the National Air Pollution Control Administration (NAPCA) was established in 1955 under the Department of Health, Education, and Welfare (HEW). A predecessor to the Department of the Interior’s Water Quality Administration (FWQA) was established in 1948 to deal with severe water pollution problems including untreated sewage and industrial waste, dying rivers and lakes, and scalding water poured directly into streams and rivers.
Environmentalists began to predict a global disaster unless public attitudes toward natural resources changed. In A Sand County Almanac, published posthumously in 1949, ecologist Aldo Leopold suggested that human beings have an ethical responsibility to live in harmony with the natural world. Silent Spring, published by Rachel Carson in 1962, carefully documented the dangers of the pesticide DDT and led to its use being banned in the United States in 1972. This book made the public aware that toxins and pesticides are health hazards.
In 1969, biologist Paul Ehrlich published The Population Bomb, which discussed the effects an expanding population has on the environment. The same year, a group of scientists published The Limits to Growth, which discussed the effects of human activity on the environment. In May 1969, Secretary General U. Thant of the United Nations declared that the Earth had only ten years to avert environmental disaster; the next month, he placed most of the responsibility for this catastrophe on the United States.
EPA building in Washington D.C.
In 1970, President Nixon signed The National Environmental Policy Act (NEPA) establishing a Council on Environmental Quality (CEQ) and requiring federal agencies to prepare Environmental Impact Statements for any major project that might potentially have environmental consequences. Later that year, the Environmental Protection Agency (www.epa.gov) was established to police air, water, and solid waste pollution.
“A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise.”
Aldo Leopold, A Sand County Almanac
Energy Crisis of the 1970s
The United States experienced a wake-up call when worldwide oil shortages led to two energy crises during the 1970s. Suddenly it became apparent that the United States would be competing with other large economies for a limited and dwindling resource. In October 1976, physicist Amory Lovins published an article in the journal Foreign Affairs called “Energy Strategy: The Road Not Taken.” Until then, energy conservation had not been considered as a serious strategy for reducing fossil fuel consumption. Government policymakers began to make energy conservation a priority.
In 1978, Congress passed the National Energy Act (NEA) to reorganize a disjointed national energy policy. The NEA created energy efficiency and conservation programs, alternative fuel programs, tax incentives, and regulatory and market-based initiatives. Many of the regulatory initiatives have since been abandoned, but the NEA included important components that became the basis for today’s clean energy incentives. Part of the NEA, the Public Utility Regulatory Policy Act (PURPA), mandated local utilities to pay their customers for excess electricity generated by their solar and wind systems.
In the late 1970s, President Jimmy Carter announced a plan to conserve energy and pursue renewable energy sources such as solar power. The U.S. government became increasingly involved in the green building and energy conservation movement, motivated by the compelling need to reduce dependence on fossil fuels and the carbon emissions resulting from their use.
Emergence of Green Building Guidelines and Regulations
Any product or building can claim to be “green,” but as the movement for sustainable building began to expand during the 1980s, it became clear that official standards are needed to certify that a building is truly energy-efficient and environmentally sound. The first certification system, the Building Research Establishment’s Environmental Assessment Method (BREEAM), was established in 1990 in the United Kingdom to measure the sustainability of new commercial buildings. The Leadership in Energy and Environmental Design (LEED) program was introduced in the U.S. in 1994 by the U.S. Green Building Council.
In 2004, the Green Building Initiative (GBI) introduced the Canadian Green Globes rating system to the United States. In 2005, the American National Standards accredited GBI as a standards developer. LEED and Green Globes certifications are both currently used in the United States.
In 2005, the National Association of Home Builders (NAHB) published the NAHB Model Green Home Building Guidelines. The Guidelines are voluntary. They cover six areas including lot preparation and design; resource efficiency; energy efficiency; water efficiency and conservation; occupancy comfort and indoor environmental quality; and operation, maintenance, and homeowner education, and can be customized to reflect local geographic and climate conditions. The NAHB National Green Building Program (NAHB Green) (www.nahbgreen.org) launched in 2008 includes an online scoring tool and a wealth of educational tools and resources for homebuilders and homebuyers. In addition, many city building codes incorporate sustainable building standards, and there are more than 50 state and city green home building initiatives in the United States.
Other building certification programs include CASBEE (Comprehensive Assessment System for Built Environment Efficiency, Japan), Green Star (Australia), BREEAM Gulf, and Evaluation Standard for Green Building (China).
Conclusion
Green building is a simple concept, but its implementation often involves complex trade-offs to achieve several objectives. A green home project strives for energy efficiency, durability, reduction of waste, an excellent indoor environment, and minimal impact on the environment. This is accomplished using a variety of building materials, technologies, and building practices. Every green building project is unique because the design and choice of materials are determined by the physical characteristics of the individual site, local availability of materials and expertise, and the needs of the building owner.
Many green building practices are becoming standard for all construction and are now part of state and local building codes. Federal, state, and local governments have invested substantially in promoting green building because of its potential to reduce the demand for energy. The green building industry is expanding rapidly, and manufacturers are responding to the demand by increasing production and lowering the costs of green products, and revolutionary new products are regularly introduced to the market. Conventional builders are rapidly adapting to these new products and technologies.
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