Residential construction is undergoing an industry-driven revolution in how houses are built thanks to a new trend known as “green building,” according to the National Association of Home Builders.

Green building – construction methodology that is designed to conserve resources -- that can help reduce a home's environmental impacts and energy consumption through innovative design, construction, and operation features.

Incorporating green building practices into land development and construction can help developers, builders and home owners save money by reducing costs.

The greatest advances in green building are occurring inside today's homes. Thanks to innovation and new applications, manufacturers, builders and energy-efficiency experts have made the following elements increasingly common:

• Double-pane windows
• Blanket and blown-in insulation materials
• Programmable thermostats with multiple settings.
• Compact fluorescent lights.
• Occupancy sensors and timers to conserve energy used for lighting needs.
• Task lighting that removes the need for whole-room lighting.
• EnergyStar Appliance Ratings.
• Tighter construction to reduce drafts.
• Building components comprised of concrete and insulation.
• Builders are making great strides in other areas as well. Materials commonly found in the home have changed.

The use of plywood, for example, has been reduced considerably. In 1978, plywood made up 89 percent of roofing products for sheathing, according to data compiled by the NAHB Research Center in Upper Marlboro, Md.

By 1999, use of plywood in roof sheathing had dropped to 27 percent. Plywood has largely been replaced by oriented strand board, which uses crushed wood debris compacted and glued together to create a stronger, more durable building material.

Building practices have changed, too. One of the most promising is something known as “frost-protected shallow foundations.” A construction technique that allows builders in cold climates to start foundations 12 inches below grade instead of at a frost line that may be three, four or five feet deep, frost-protected shallow foundations save energy, excavation and construction time, labor, materials, and money, and disturb less soil than conventional foundations, according to the builders association.

Frost-protected insulated footings were used as early as the 1930's by Frank Lloyd Wright in the Chicago area; in recent years several thousand homes have been built using the practice.

What will the green home of the future look like? According to the NAHB, experts cite the following advances and applications, many of which are beyond the experimental stage:

• Thermal storage heaters" that store heat at off-peak energy times for use at peak times.
• Cogeneration that uses solar/fossil fuel to generate heat/hot water/electricity and sell electricity back to the local power company.
• Natural gas-fired heat pumps and central air conditioners that use natural gas to fuel internal combustion engines for fans.
• Ground source heat pumps.
• Cool roofing materials that absorb heat during the day and redirect it back into the home at night.
• Vacuum insulation panels that are three times more heat absorbent that products on the market today.
• Residential fuel cells that allow power generation at an individual residential unit level.

Looking beyond materials, there are steps builders can take to build greener -- but the industry needs help from others. Congress, for example, can assist the housing industry by providing a tax credit so that builders can construct and maintain new energy-efficient single-family and multifamily housing.

Builders are also pressing Congress to pass a tax credit for homeowners for projects that increase energy efficiency in existing homes.

What can home buyers do to save energy? Here are some suggestions from builders:

• Check for the appropriate amount of insulation for the climate in the walls, roof assembly, and floor.
• Look for high-performance, double-pane windows that have high-performance (low-e coated or solar control spectrally selective) glass that helps reduce heat loss in the winter and heat gain in the summer.
• Ask for highly efficient heating and cooling equipment. Nearly 50 percent of a typical home's utility bill goes toward heating and cooling.
• Choose energy-efficient appliances and lighting by checking the appliance's
• EnergyGuide label which will provide an estimate of the unit's annual operating costs.

In some parts of the country, consumers can consider using the sun's energy to help reduce utility bills via solar water heaters that can meet a home's hot water needs and photovoltaic systems that can convert sunlight into electricity.

Use hot water wisely by turning the water heater's thermostat setting down to 115 from 120 degrees Fahrenheit; buying an energy-efficient water heater; installing non-aerating, low-flow faucets and showerheads; using the “warm” water setting on the clothes washer instead of the "hot" water setting; and setting the dishwasher to “energy saver” or “water saver.”

Check to ensure that the house is well sealed against air leakage. In some areas of the country, as much as 30 percent to 40 percent of a home's energy load use be attributed to the infiltration of outside air into the home