Conservation Consultants Inc. will debut its roof garden this week as a model for saving energy and reducing air pollution.

A ribbon will be cut on the South Side building's "green roof" Wednesday, after which it will be open to school and neighborhood groups, businesses and the public by appointment.

The nonprofit agency will also hold a free energy expo Oct. 12 to help people save energy in their homes and plan greener lifestyles.

Conservation Consultants bought and renovated the 100-year-old building at 64 S. 14th St. in 1993 for its offices and as a green demonstration project before the U.S. Green Building Council established Leadership in Energy and Environmental Design, or LEED, standards. It has since been LEED certified at the gold level, said Ann Gerace, the executive director of Conservation Consultants.

The roof garden, which is 100 feet by 19 feet, has 18 varieties of plants chosen for biodiversity, ability to absorb air pollutants, low-maintenance needs and aesthetics. They are nourished from a rain barrel.

Melanie Tuck, the green roof consultant, said the plantings serve several purposes. By absorbing sunlight, they keep the roof from reflecting heat into the building and the atmosphere. As an insulator, they will cut interior energy usage by 10 percent.

That's in addition to the building's reduction of energy use to 30 percent of average commercial use, said Ms. Gerace.

The plantings can also prevent the run-off of up to 11,000 gallons of storm water, said Dave Defide, the chief financial and executive officer of Conservation Consultants, which has contracts with six utility companies to conduct free energy audits for low-income customers. The agency conducts home energy audits for others for a fee.

The state Department of Environmental Protection gave the agency $54,000 to install the roof garden, which weighs 20,000 pounds. It shares the roof with a solar module that will heat water for the three-story building and its four tenants, all nonprofit environmental agencies.

Mr. Defide said the plants will need watering only every two to three weeks once they are established.

Next month's free expo will run from 1 to 5 p.m. at the Conservation Consultants building. It will feature 41 informational tables, and there will be chances to win a home insulation or home-energy audit. Those who bring up to three incandescent light bulbs can trade them for compact fluorescent bulbs, which last years longer and use less energy.

The expo will also offer activities for children and demonstrate the building's E-Mod solar unit, which pumps water and enables lighting.

To tour the roof garden, call Ms. Gerace at 412-431-4449, ext. 200, or e-mail anng@ccicenter.org.