The popularity of green building has skyrocketed in the past year, as more builders and homeowners try to create homes that are environmentally friendly.

Pruitt-Balthazar Custom Homes

This is an artist's rendering of an energy-efficient home built by Pruitt-Balthazar Custom Homes that will be part of the Parade of Homes in Frisco this year.

This year's Parade of Homes, which runs through June 10 in Frisco, will follow that theme. All of the showcase homes meet or exceed requirements for the federal Energy Star program, which means they will be 15 percent more energy-efficient than standard houses. It's a designation now mandatory in all new homes in Frisco.

But many of the most popular green building products and techniques aren't actually new.

Passive solar design, for example, is the granddaddy of green construction, says David Johnston, an environmental building consultant and author of Green Remodeling: Changing the World One Room at a Time.

But the idea started thousands of years ago, with the ancient Greeks.

The premise is to build your house facing south and minimize the windows on the east and west sides, to keep the house cool in the summer and warm in the winter. That can save up to 50 percent of the energy in a house, Mr. Johnston says.

"It's unbelievably simple, and it's been around for 3,500 years," he says. "But once we discovered air conditioning, we forgot about it."

Energy efficiency is a key to today's green movement. And many builders are returning to techniques first popularized during the oil crisis of the 1970s, when they experimented with more efficient ways to insulate a home. Those include framing the house with 2-by-6s instead of 2-by-4s, allowing for two extra inches of insulation.

But insulating a house so tightly has led to another problem: reduced indoor air quality. Many home materials, including carpet, paint and woodwork, can release volatile organic compounds into the air, leading to health concerns.

One of the biggest changes in the recent green building movement is combating the release of those gases, Mr. Johnston says. In the past few years, for example, manufacturers have tried to create alternatives to particleboard that don't include formaldehyde, a carcinogen. Now they're creating boards made from wheat and rice to be used in cabinets, shelving and other areas of a home.

The old low-flow toilet has also gotten redone in recent years. A decade ago, when the government began requiring toilets to use just 1.6 gallons of water per flush, the toilets didn't really work well, says Dan Fette, chairman of the Green Built North Texas Council, part of the Home Builders Association of Greater Dallas.

Now, manufacturers have redesigned toilets with wider trapways and more glazing so they function better, he says. The government also recently introduced a "high efficiency" rating for toilets that use just 1.28 gallons per flush.

Although Earth-friendly construction options have existed for a long time, not many people knew about them until recently.

"The technology may have been there, at least in its raw form, for many years," Mr. Fette says. "But people weren't asking for it, and it didn't get used."