Although the number of proponents of environmentally-friendly construction practices is growing, it's still not easy building "green."

The problem is inertia, some experts say. When builders and contractors are faced with any kind of change, they worry about costs. However, green building advocates counter that if the project is built correctly, the builder will make money.

Building green has many interpretations, but the goals include efficient use of land and energy, water conservation, improved indoor air quality, and resource conservation, primarily by using recycled materials.

Most commercial and residential builders focus their green building efforts on landscaping. They try to save trees on building sites and use native species and hybrids, because native species tend to require less water than imported varieties.

The impetus for green is still coming primarily from the government and institutions, although residential and commercial builders' associations are coming around, slowly.

The federal government can reduce the cost of green buildings by taking advantage of economies of scale. While the initial outlay might be higher than it would be with conventional materials and practices, the efficiencies achieved will pay for themselves over time.

Not all residential builders see red ink when someone says green. According to the National Association of Home Builders, there are more than a dozen green building programs around the country, with one in Denver accounting for 1,200 houses a year.

The NAHB, which represents the nation's residential builders, has been trying to persuade its members to use alternatives to lumber in home construction.

Residential green building first took root in Austin, Texas, in the early 1980s, when Austin Energy, the municipally owned electric utility, began a program to promote energy efficiency.

The program was so successful that Austin expanded our focus to much more than energy, including water conservation, using recycled building materials, and community issues.

Indoor air quality was added because many Austin residents suffer from allergies related to the large number of juniper trees in the region.

To builders and designers, the program essentially provides expertise, through monthly seminars and one-on-one work. Mechanical engineers on staff help with the work of making building systems more efficient.

Single-family homes are then rated on a scale of one to five stars. Continuous advertising is provided to familiarize the public with the benefits of living in a green-built home -- saving money on utility bills, reducing demands on power plants, and salvaging building materials.

Because of Austin's problems with allergies, indoor air quality seems to be the major selling point of green building among consumers there.

Indoor air quality that has led the charge toward green building over the last decade.

Most of the furniture in offices and houses has been veneered particleboard using glues with high VOCs -- volatile organic compounds, which can trigger allergies. The same kinds of glues are used in carpeting.

Owners of some green buildings have the air flushed every night with fresh filtered air.

Often there are carbon-monoxide monitors in offices throughout the building. If the monitors determine that air in a room is bad, fresh air will be brought in.

The buildup of bad air is the reason why most office workers tend to feel tired after lunch.

But there is more to green building than air.

Using recycled building materials, as well as ensuring that lumber does not come from old-growth forests, is of primary concern.

Since cutting in old-growth forests is not a choice for such a project, the only source is salvage.

One federal project used boom logs from the Columbia River in Oregon. There are firms that search the East Coast and Midwest for old factories and warehouses that are set for demolition and have old-growth lumber that can be salvaged.

If lumber is unavailable, some projects are using steel, an appropriately green decision, since American-made steel these days has a recycled content of 90 percent, meaning it has been used somewhere before.

It is not just lumber and steel that are being recycled. Concrete is being ground up and reused, as well as recycle wallpaper and fabrics and carpeting with recycled materials.

Energy efficiency is being achieved using large super-insulated windows and skylights to bring in as much natural light as possible. At night, energy-efficient fixtures are the main light source.

No building can be totally green, especially when you are talking about materials.

Some recycled materials need to be replaced more often than conventional materials, and the need to change them negates their value as green.

For example, the roof at one federal green project is standing-seam steel with no recycled material; it was chosen because it is known to last 50 years. The building's siding is relatively new -- a cement-fiber product that with a coat of latex paint. It, too, will last 50 years.

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