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CORVALLIS, Ore. -  The mandates of building codes and desire for low costs are still the driving forces behind the structural materials usually chosen for buildings, a new survey suggests, despite Oregon's increasing demand for use of "green" construction techniques.

The analysis reflected interviews with more than 30 architects, engineers and other design professionals, and showed that they wanted to build environmentally friendly structures but were often bound by the constraints of budget, code requirements and some uncertainty as to what constituted the best green structural materials or construction approaches.

Amid the significant pressures to appear "green" and sustainable, the survey also cited some concerns about "greenwashing," in which the manufacturers of every product insisted they were the most environmentally benign and building designers were unsure who they could trust.

"These are actually pretty complex questions and there are some gaps in information we need to help address," said Chris Knowles, an assistant professor with the Oregon Wood Innovation Center at Oregon State University. "These professionals are interested in green construction, they are usually informed about it, but it's still difficult to make the most informed and optimal decisions, and they also have cost and code issues they struggle with."

This survey was conducted by OSU, the University of Oregon and Portland State University, with support from the Oregon Forest Resources Institute and the Oregon Built Environmental and Sustainable Technologies center, or Oregon BEST.

Also somewhat surprising, officials said, was that the LEED rating system developed by the U.S. Green Energy Council often had little influence on materials chosen for the structural system. The LEED ratings and certification carry significant value, the building designers said, but types and volumes of materials used carry minimal weight in the LEED analysis and as a result have little effect on material choice, whether that be wood, concrete, or steel.

Among the findings of the survey:

• Wood is generally seen as a green and sustainable building material, but the frequent presence of formaldehyde-based adhesives in engineered wood products causes concerns about gas emissions;

• Availability of large volumes of certified wood products sometimes limits their use on larger projects, with preference given to the certification program operated by the Forest Stewardship Council;

• Concrete and steel sometimes are favored due to their ability to add thermal mass to a structure that makes heating and cooling more energy efficient, or because it's necessary on taller structures more than several stories high;

• The availability of reliable and unbiased sources of information is a concern, and product representatives or industry literature are generally seen as biased;

• The "life cycle analysis" is respected as a useful tool to make long-term environmental comparisons between use of wood, concrete or steel and based in part on that approach, wood is often seen as the building material of choice;

• The group identified a need for continuing education courses to study these issues and stay updated on the latest approaches.