Site Managment
Water Conservation and Efficiency
Energy Efficiency
Resource Management
Indoor Air Quality

Site Management
Although the focus of green building is typically on the built structures located on a site, the design of the site and its natural elements can have a significant environmental impact.  Early decisions about how to incorporate the home into the site can have significant long-term effects on local and regional ecosystems, as well as on demand for water, chemical, and pesticides for site management.  Good design decisions can result in attractive, easy to maintain landscaping that protects native plant and animal species and contributes to the health of habitats.

The way in which a home is, or is not integrated into the site can have various effects.  Rain that falls on a site can be either a detriment, causing soil erosion an runoff of chemicals and pesticides, or an opportunity to offset the potable water demand and recharge underground aquifers.  Plant growth can be a burden, requiring regular upkeep, watering, and chemicals, or an enhancement that provides shade and improved occupant comfort, habitat for native species, and a mechanism for absorbing carbon and enriching the soil.

Site design should take into consideration not only the aesthetic and functional preferences of the occupants but also long-term management needs, preservation principles, and potential impacts on local and regional ecosystems.

Elements of Site Management include:

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Water Conservation and Efficiency
In the United States, approximately 340 billion gallons of fresh water is withdrawn per day from rivers and reservoirs to support residential, commercial, industrial, agricultural, and recreational activities.  This accounts for about one-fourth of the nation’s total supply of renewable fresh water.  Almost 65% of this water is discharged to rivers, streams and other bodies of water after use and, in some cases, treatment.  Additionally, water is withdrawn from underground aquifers.  In some parts of the United States, water levels in these aquifers have dropped more than 100 feet since the 1940’s.

On an annual basis, the water deficit in the United States is currently estimated at about 3700 billion gallons.  In other words, Americans extract 3700 billion gallons per year more than they return to the natural water system to recharge aquifers and other water sources.

Water efficiency measures in new homes can easily reduce water usage by 30% or more.  In a typical home, savings of 30,000 gallons of water a year can be achieved very cost-effectively.  This results in average annual water utility savings of about $100 per year. 

As communities grow, increased demand for water leads to additional maintenance and higher costs for municipal supply and treatment facilities.  New homes that use water efficiently have lower water use fees and reduced sewage volumes.

Elements of Water Conservation and Efficiency include:

Energy Efficiency
In the past 50 years, the average size of new homes has doubled.  As a result, total fossil fuel use in homes has been steadily increasing.  The average American consumes 5 times more energy than the average global citizen.

Conventional fossil-based generation of electricity releases carbon dioxide, which contributes to global climate change. Coal-fired electric utilities emit almost one-third of the country’s anthropogenic nitrogen oxides, the precursor of smog, and two-thirds the sulfur dioxide, which causes acid rain.  They also emit more fine particulate material than any other activity in the United States.  Natural gas, nuclear fission, and hydroelectric generators all have adverse environmental impacts as well.  Natural gas is a major source of nitrogen oxides and greenhouse gas emissions.  Nuclear power increases the potential for catastrophic accidents and raises significant waste transportation and disposal issues.  Hydroelectric generating plants disrupt natural water flows, disturbing aquatic habitat and reducing fish populations. 

Buildings consume approximately 37%  of the energy and 68% of the electricity produced in the United States annually, according to the U.S. Department of Energy.  In 2006, total emissions from residential buildings were responsible for 1.2 billion metric tons of CO? emissions, or 20% of the U.S. total.

Building green homes is one of the best strategies for meeting the challenge of climate change because the technology to make substantial reductions in energy and CO? emissions already exists.  The average certified LEED home uses 30% to 40% less electricity and saves more than 100 metric tons of CO? emissions over its lifetime.  Modest investments in energy-saving and other climate-friendly technologies can yield homes and communities that are healthier and more comfortable, durable, energy-efficient, and environmentally responsible places to live.

Elements of Energy Efficiency include:

Resource Management
The choice of building materials is important for sustainable homebuilding because of the extraction, processing and transportation they require.  Activities to produce building material pollute the air and water, destroy natural habitats, and deplete natural resources.  Construction and demolition wastes constitute about 40% of the total solid waste stream in the United States.

Good design decisions, particularly in the framing of homes, can significantly reduce demand for framing materials, as well as the associated waste and embedded energy.  Without even changing the home design, a builder can save framing materials and reduce site waste by planning appropriately and communicating design to the framing team through detailed framing documents and/or scopes of work.

Sources should be evaluated when materials are selected for a project.  Reclaimed materials can be substituted for new materials, saving costs and reducing resource use.  Recycled-content materials make use of material that would otherwise be deposited in landfills.  Use of local materials supports the local economy and reduces the harmful impacts of long-distance transport.  Use of third-party-certified wood promotes good stewardship of forests and related ecosystems.  Use of low-emitting materials will improve the indoor air quality in the home and reduce demand for materials with volatile toxic compounds.

An increasing number of public and private waste management operations have reduced construction debris volumes by recycling these materials.  Recovery activities typically begin at the job site, with separation into multiple bins or disposal areas.  In some areas, regional recycling facilities accept commingled waste and separate the recyclable materials from those that must go to the landfill.  These facilities can achieve waste diversion rates of 80% or greater.

Indoor Air Quality
Americans spend on average 90% of their time indoors, where levels of pollutants may run two to five times higher than outdoors, according to the U.S. Environmental Protection Agency.  Many of the pollutants found indoors can cause health reactions in the estimated 17 million Americans who suffer from asthma and 40 million who have allergies, contributing to millions of days absent from school and work.

Homeowners are just beginning to realize the link between their health and their homes.  Hazardous household pollutants may include carbon monoxide, radon, formaldehyde, mold, dirt and dust, pet dander, and residue from tobacco smoke and candles.  Many homeowners also store various chemicals inside their homes as well, including pesticides, fertilizers, solvents, grease, oils, degreasers, gasoline, antifreeze, strong detergents, thinners, and oil-based paints.

Over the past 20 years, research and experience have improved our understanding of what is involved in attaining high indoor environmental quality and revealed manufacturing and construction practices that can prevent problems from arising.  Preventing indoor air quality problems is generally much less expensive than identifying and solving them after they occur.  Generally, there are three types of strategies:  source removal, source control, and dilution.

Source removal is the most practical way to ensure that harmful chemical compounds are not brought into the home.  Evaluating the properties of adhesives, paints, carpets, composite wood products, and furniture and selecting materials with low levels of potentially irritating off-gassing can reduce occupants’ exposure.  Scheduling deliveries and sequencing construction activities can reduce exposure of materials to moisture and absorption of off-gassed contaminants. 

Source control strategies focus on capturing pollutants that are known to exist in a home.  For example, filtering the supply air stream removes particulates that would otherwise be continuously recirculated  through the home.  Protection of air-handling systems during construction and a building flushout prior to occupancy further reduce the potential for problems. 

Dilution involves the use of fresh outside air to ventilate a home and exhaust pollutants to the outdoors.  This may also help control moisture within the home.  Most new homes in the United States do not have mechanical fresh-air ventilation systems.  The typical air-handling systems in new homes merely recirculate the air within the home, continuously pumping indoor pollutants through the rooms rather than exhausting them.

Another aspect of indoor air quality is occupant comfort.  The proper installation of automatic sensors and controls to maintain proper temperature, humidity, and ventilation in occupied spaces helps maintain optimal air quality.  Surprisingly, sensors to alert a home’s occupants to deadly carbon monoxide concentrations are frequently not required by current codes but should be included in all new homes.  Letting occupants fully and effectively control their thermal environment can reduce hot-cold compliant calls and generally raise satisfaction levels.

Elements of Indoor Air Quality include: