Who says there is nothing new under the sun?

When Koben Calhoun set out to buy his first home a few years ago, he was most interested in price and place. In his mid-20s, single and not fond of driving on the weekends, he wanted a home near friends and amenities in North Seattle. He also needed a yard for his dog, and he wanted to pay less than $500,000.

Unsuccessful in his search, he took a break, but by February he was ready to go back out again, this time with another criteria on the wish list. He wanted his home to be green.

Calhoun learned more about carbon emissions, indoor air quality and sustainable building methods after getting a job with Built Green, a regional organization affiliated with the Master Builders Association of King and Snohomish Counties that helps create and promote green building standards.

"I thought it was important to put my money where my passion and beliefs are," he said.

If the sale closes without a hitch, Calhoun's search will be over by the end of October when he moves into his three-bedroom townhouse, which earned Built Green's highest rating of five stars.

Although Calhoun's job allows him unique insight into sustainable and healthy construction, buyers need not work in the industry to learn about green homes. Resources for prospective homebuyers are sprouting up around the Northwest.

To aid in his search, Calhoun sought out an agent at GreenWorks Realty. The company aims "to connect people with homes and property that match their values" and its agents are trained in the nuances of green certifications and amenities.

In June, prospective buyers gained another resource when a green-certification checklist was added to the search criteria for the Northwest's real-estate listings database, maintained by the Northwest Multiple Listing Service (NWMLS). This addition was instigated by GreenWorks co-founder Ben Kaufman, even though it means the very information in which his company specializes will now be easily available to all real-estate agents.

Kaufman said the move fit into his company's mission, and hoped "the rising tide will lift all boats."

"It's like Google providing free maps; people will adopt the technology," he said. "Green homes are the next Microsoft, the next computer. Everyone will want one."

For prospective buyers who want to explore the green market independently, there are open houses and seminars almost every weekend. A guidebook of September events featuring Built Green homes is available at QFCs and Tully's Coffee shops throughout King, Snohomish and Pierce counties.

Built Green's monthly newsletter (www.builtgreen.net/newsletter.html) also lists events, as does the Northwest Ecobuilding Guild (www.ecobuilding.org).

But finding out about other green events sometimes depends on luck or who you know. More than 100 people showed up to an unadvertised tour of a home on Bainbridge Island.

Its rooftop full of solar panels make it the first home in the state that's expected to produce more power than it uses. "It's like a mini-powerplant," said Russ Hamlet, the architect who designed the home as the debut project of a local developer, Lisa Martin of Rolling Bay Land.

Five people piled out of a Toyota Prius and another man stopped by on a whim, still sweaty from his bike ride. Shoes were scattered outside the front door as people wandered the hallways and gawked from the yard at the photovoltaic panels and the Thermomax water-heating system.

Besides its solar amenities, the house also was designed to stay cool and breezy in summer and cozy in the winter, and many of the building materials were salvaged or recycled.

Hamlet estimates that not counting the solar panels, he spent about 20 percent more than he would have on a comparably-sized house using traditional methods and supplies.

While Martin and Hamlet are a new development team, other larger developers throughout the region have been working for years to green their practices and to help meet the growing demand for greener homes. Martha Rose Construction (www.martharoseconstruction.com), Sunshine Construction (www.sunshineconstruction.biz), Noland Homes (www.nolandhomes.com) and Glover Homes (www.gloverhomes.com) are some of the developers that have been at the forefront. All have information about current projects and open houses on their Web sites.

Pryde + Johnson (www.prydejohnson.com) has unveiled several green projects in the past few months with its Hjärta and Florera condos in Ballard and Green Lake, respectively, and the Ashworth Cottages near Green Lake.

Several planned, green communities have gone up on the Eastside recently, including the progressive mixed-use, park-and-ride community of Issaquah Highlands by Port Blakely Communities (www.portblakely.com).

Another green-housing innovation that's popular in Europe and Japan, but just starting to catch on in the Northwest, is custom, factory-built modular homes. Web sites such as worldchanging.com and treehugger.com describe the explosive growth of the prefabricated-housing industry.

Based in the Bay area, prefab architecture firm Michelle Kaufman Designs (www.mkd-arc.com) recently bought a factory south of Tacoma to meet a growing demand for green prefab modular houses in Washington.

Kaufman's homes employ renewable, nontoxic building materials and sustainable design principles, while also streamlining the building process. Leftover materials can be used in the next project, so there's little construction waste.

Even with this proliferation of green building, finding the perfect home, let alone the perfect green home, isn't easy.

"People are hungry for the product. We can't find enough for those that want them," said Joe Nabbefeld, a real-estate agent at GreenWorks.

Calhoun agrees. It took him more than two years to find his home and he had to accept that he couldn't afford to do everything he wants right now.

Instead, he worked with Noland Homes to make a few, simple upgrades. The builders were using IceStone — made of recycled glass and cement — on another job, so he requested some of the excess go into his kitchen counters instead of granite. He opted out of carpet in the basement to improve indoor air quality, and he invested $1,000 to have the place wired for solar panels he'd like to install when he has more money.

"It can be a frustrating and intimidating process," said Calhoun, but it was something he believed in. "It's a niche market right now, but I think it's going to go mainstream. I wanted to support the builders so that this isn't just a trend, but becomes a standard way of building."