Bigger houses these days often mean two-story foyers; spacious kitchens with center islands; a family room with a vaulted ceiling; four bedrooms, including a master suite, room-sized walk-in closets; and a three-car garage.

But the bigger the house, the more resources it takes to build and power it.

Rick Alfandre, a New Paltz, N.Y., architect specializing in green technologies, said big isn't necessarily better.

"People have to think about how they'd like to live, instead of picking a plan out of a book," he said.

Consider the environmental impact of construction materials.

An oak tree with a diameter of 20 inches and a length of 42 feet of usable wood generates roughly 260 board feet. A typical 2,000-square-foot house, which requires 26,700 board feet to build, would mean the destruction of 102 oak trees of that size, according to the Idaho Forest Products Commission.

A 4,000-square-foot home would require cutting down 204 oak trees.

Concrete, which is used in foundations, is made up of aggregate, such as sand and gravel, bound together with a cement. Making cement consumes a tremendous amount of energy and contributes to greenhouse gas emissions, according to the New York Academy of Sciences.

Vinyl siding is commonly used, but when it catches on fire, it becomes toxic, said Doug Hoffman, of Eco-Con Building Systems in Woodstock.

Another toxic material is paint. According to the Environmental Protection Agency, vapors or volatile organic compounds in paint can cause serious health problems like liver damage and cancer.

Energy efficiency also is an issue.

John Maserjian, a Central Hudson Gas & Electric Corp. spokesman, said a typical home uses 500 to 600 kilowatt-hours of electricity a month.

In mega-homes, where amenities include television sets in every room, indoor pools and exercise rooms, living spaces with elevated ceilings, modern fireplaces and more, energy usage could be much higher, he said.

Homes that aren't energy-efficient increase the need to construct power plants and dependency on fossil fuels. They also increase carbon dioxide emissions that contribute to climate change and sulfur dioxide emissions that contribute to air pollution and acid rain, according to Energy Federation, distributors of energy-efficient products.

Ideally, larger homes would lessen their effect on the environment by going green, said Manna Jo Greene of Hudson River Sloop Clearwater, an environmental education and advocacy group in Poughkeepsie, N.Y.

Green homes are created using natural materials, solar concepts for heating and cooling, attached solar greenhouses and naturally cooled pantries, according to DreamGreenHomes .com.

But you don't have to downsize your home to lessen its environmental impact.

James Steinberg lives in a 5,400-square-foot home in Rhinebeck, N.Y. Architect Steve Mensch designed the home in response to its surroundings, a secluded hill with views of the Catskill Mountains.

Walls of glass allow the sun to warm up the living spaces during the day in winter. In summer, the walls slide back, allowing the breeze to cool the one-floor home.

"McMansions aren't for us," said Steinberg, a Poughkeepsie lawyer. "I'm a huge believer in the Al Gore movement. The time has come to go green."

But Steinberg is an exception.

Real estate agent Bill Beehler of Lagrangeville, N.Y., said requests for environmentally friendly homes are uncommon.

"When you get into the expensive homes, they want fantasy bedrooms and entertainment rooms with all the bells and whistles," he said.