Here are stories of three boards who are doing just that in the practical real world — conserving what resources we have left while saving money in the not-so-long run. At the moment, green retrofits pay for themselves in 10 years at the most, and, the general consensus "is that payback times are going to get shorter, not longer, as energy prices go up," says Larsen Plano, a project manager with the nonprofit Community Environmental Center (CEC) in Long Island City, Queens.

A Garden Grows in Brooklyn

The dawn of the green era came to the Art Deco co-op at 140 Eighth Avenue (below) in Brooklyn's Park Slope in the late 1990s. That was when the board renegotiated its mortgage and used the money to install energy-efficient double-glazed windows on all 92 units.

"Our building has just kept up with the flow," says board president Reba Snyder. "For instance, when we did some minor work on the roof, we decided to cover it with reflective silver paint," which helps repel sunlight and keeps the building cooler than otherwise. The co-op also took advantage of a city program to install more than 100 low-flow toilets for free, which helped to sharp reduce the water bill. Other steps have included re-landscaping the building's two courtyards; painting the hallways with nontoxic paints (low in so-called volatile organic compounds); replacing lightbulbs in common areas with energy-saving compact fluorescent lamps (CFLs); and urging shareholders to follow suit in their apartments.

Using persuasion has worked, Snyder says. Aside from the financial incentive, the shareholders wanted to be more responsible to the environment. This led the co-op to create a Green Committee that includes a shareholder who's certified in energy-efficient audits, and another who wrote a thesis on sustainable energy for buildings. "They send us e-mails and we meet and discuss them. They raise questions about saving water, reducing heating bills."

But there are limits. This co-op, built in the 1930s, isn't capable of accommodating some of the newest technology without major, costly renovations. "We're going to have to replace the roof in the next year," says Snyder, "and we looked into building a 'green roof' with a garden to reduce heating and cooling costs and [with] a system to catch rainwater [to water the garden without a net increase in water use]. But the engineer's report said we would need major structural changes."

That doesn't mean that such modifications are impossible in all older buildings. "There are no generalities," says Leslie Hoffman, executive director of Earth Pledge, a Manhattan-based nonprofit organization that promotes green roofs and other initiatives. A "green roof," she points out, is not a few potted philodendrons but an "engineered, lightweight roofing system that supports living plants," at a cost of $12 to $60 per square foot. Such gardens reduce energy consumption by combating the so-called urban heat-island effect. "The savings vary from building to building but a green garden can take 25 percent off a building's air conditioning load."

And they can be suitable for older buildings. "Our offices are in a 1902 brownstone and we have the first green roof in New York, built in the late 1990s," Hoffman notes, adding that there are now about 150 green roofs in the city. "We had to make some modifications, but they were affordable. It's always worth looking into."

Careddu of the CEC agrees. "A lot of management companies are interested in greening their properties. They see it as a way of getting better rents and resale prices, and some management firms want to do the right thing."

Green, as in Greenwich

Robert and Maura Geils live in a co-op at 350 Bleecker Street (at right) in Greenwich Village. Since Robert is the board's treasurer, the Geilses decided that the best way to green their building would be to lead by example.

The 1960s-era building is looking at a major expense in the next few years: replacing the windows in all 120 units at a total cost of roughly half-a-million dollars. To prove that environmentally friendly solutions to such problems can also make economic sense, the Geilses spent $10,000 of their own money to replace the leaky windows in their apartment with state-of-the-art, double-pane, vacuum-sealed, energy-efficient windows.

"We're using our apartment as an example of how the windows cut down on heating and cooling costs, reduce noise, and increase the value of our unit," says Robert. "When I close the window, I can't even hear a bus go by." He estimates the windows have increased his apartment's value by more than the amount he spent.