In another case, the client was a government contractor that required a top-secret security clearance for nuclear research. “The client requested a green building that included an extensive day-lighting system (with impressive skylights)” which negated the top-secret security needed at the site. Once completed, “the client sued the designer for negligence.”

So how do green projects avoid lawsuits? Corbett said it's best to steer clear of the “low-bid selection process. Experience and familiarity with building materials and methods of LEED certification is at a premium, not the low-bidder.”

According to the US Green Building Council, 1.84% is the average additional cost of going green. For the basic level of certification, average costs rise .66%; costs top out at an additional 6.5% for the platinum level. While direct benefits of green design such as energy savings (20-55%), carbon savings (35-65%), water use savings (30-50%) and waste costs savings (50-90%) can cut into those added costs for sustainable projects, indirect benefits should be taken into account as well.

Employee productivity is chief among them. According to Corbett, it's estimated that between $29 billion – $168 billion in productivity is lost each year due to poor building design, whether that's due to poor lighting, ventilation or absenteeism. He said adding windows and views to workstations could improve productivity 10%; day-lighting or high-performance lighting (6.7%) and individual temperature control (3.6%).

Development of green buildings this year is expected to top $12 billion this year. That's up from $6 billion just a couple of years ago, Corbett said. While office buildings top the news for sustainable development, all product types are touched by green design. Corbett said 23% of new retail sites carry a green element, and two-thirds of homebuilders are already onboard. By the year 2010 between 5-10% of new homes will have green options. “That's a $19 billion – $38 billion market,” Corbett noted.

Higher education is another area that has potential, where 78% of projects could have LEED elements in the future. In addition, 50% of public schools in k-12 were built from 1950-69, so as they become outdated or need renovations, there's green potential. Healthcare is also seeing progress with 225 construction projects being designed with some level of sustainability in mind.

So far, industrial projects have lagged, only 5% of all projects are LEED registered, but the opportunities are there. Corbett noted that Toyota, Wal-Mart, JPL and Honda are among the early adopters in that field.

With all that potential for green development and design Corbett said it's inevitable that claims could and would occur. “The best way to manage exposure and risk is through direct contact with the client,” he said. “We see the potential for costs coming down, and we'll have more experienced people out there, but right now we're at a level where we need to make sure (the architects and engineers) are educating the client.”