"Tie-dye" might sum up public stereotypes of green building, but not for the homebuilders attending "Greening the 21st Century," a sustainable-building conference held in Seattle this month. It wouldn't be a green building conference without straw-bale builders and organic gardeners, but they weren’t the majority of attendees.

At least half of the roughly 275 attendees were builders right off the job site, here to learn more about building energy-efficient and sustainable homes. The remaining attendees were realtors, decorators, association directors, lenders, and an impressive line-up of speakers. The event was organized by Built Green and the Master Builders Association of King and Snohomish Counties in Washington state.

Built Green doesn't seem as energy-centric as other groups, like EVHA and EEBA, but there was a moderate amount of energy-related content, in proportion to its footprint on Built Green's compliance checklist.

The recurring energy theme at this year's conference was "embodied energy." Keynote speaker Steve Loken of Loken Builders addressed it, and other presenters repeated the concept: Builders should be conscious of the energy it takes to make, transport and later recycle building materials.

For example, cement is easy to pour but energy intensive to manufacture and recycle. Loken described recycling the concrete waste from a Wal-Mart store demolition. The old concrete was ground up to make aggregate for a new store on the site.

"This is the machine that ate Wal-Mart," Loken said, showing a photo of the recycling subcontractor's equipment. "Chewed up the whole thing. The guy got swamped with calls. Communities were lining up so he could eat their Wal-Marts, too."

Loken said that the most important thing about a Built Green home is not whether builders choose green materials like straw bale or fiber cement, but whether that building will achieve and maintain maximum energy efficiency for the next 75 to 100 years.

"Green building is energy conservation in new clothes," Loken said. "If you look at the environmental impact of all the stuff in the green building program, the impact of energy conservation is huge. Compared to that, the impact of the materials you choose is small."

Among the 43 exhibitors were a handful efficiency-related booths. Two exhibitors showed energy-efficient lighting in their booths.Energy Star Homes and three solar power vendors also exhibited.

There were nine seminar sessions in three concurrent time slots, and three hands-on workshops, plus ample time for the exhibits. Next year, perhaps the seminars will be spread out so attendees can participate in more of them.

Too often a builder's first experience with solar energy is a first installation, making many builders hesitant to make that leap of faith. Attendees had two opportunities to jump right in. Mike Nelson gave solar workshop participants a valuable, hands-on demonstration of installing net-metered solar power. Nelson was also a panelist in an informative session on the realities of active and passive solar.

Speaker Jim Soules, owner of The Cottage Company, told of including solar panels in one of his innovative housing developments. The homeowners weren't interested, he said. They didn't understand solar power, and didn't value having it in their development.

But Soules said he will include photovoltaic in his next development. I asked him why he would incur the cost, when financial payback was clearly not the motivator. "To keep working on it somehow," he said. "You've got to keep doing it to learn about it, and eventually people will accept it."

The atmosphere at "Greening the 21st Century" was casual and inquisitive. The conference demonstrated the strong interest in sustainable building in the Northwest and around the world. If you missed this year's conference, watch for it in 2006. Just leave your tie and your tie-dye at home.