Forget all the arguments about Mother Earth. If you want administrators to take environmental issues seriously, you need to think green (as in dollars).

That was the message of a presentation Monday at the annual meeting of the Society for College and University Planning. The comments came from a report by Architerra, a Boston architecture firm that promotes environmental sustainability in its designs. The firm surveyed 11 private colleges in Boston on a range of their practices and philosophies, promising that replies would not be linked to individual institutions. The colleges were all members of the Boston Consortium, which includes top research universities, smaller arts institutions and engineering colleges, among other institutions.

Asked what motivated colleges to adopt environmentally sound practices, the top answer was cost savings. But asked what was holding colleges back from adopting more such practices, the top answers were fear of added costs and inertia. Vicki Sirianni, a consultant with the Boston Consortium, said it was "almost terrifying" to realize how much financial considerations were dominating environmental issues on campus. "We are so concerned about costs that we will purchase something even if it kills us," she said, joking only in part.

Ellen A. Watts, a principal at Architerra, reviewed the results of the survey, stressing the extent to which the data demonstrated a wide variation in their practices.

• Institutions were asked whether they followed 29 practices that promote sustainability and the institutional response rates ranged from 41 percent to 83 percent.
• Of those practices, those with which 100 percent of institutions in the survey complied were recycling of white paper, construction recycling, and water conservation. Those practices with the lowest levels of adaptation included composting, low irrigation landscaping, concrete recycling, and snow and ice removal.
• Only six buildings on the 11 campuses have gone through the process of becoming certified as "green" facilities. Those six buildings are at three of the colleges in the survey.
• The 11 institutions used a total of 1.2 billion gallons of water a year, but the average use per person ranged from 921 to 12,300 gallons.
• The 11 institutions had a total of 32,000 parking spaces, with the average ratio of parking space to person on campus (whether student or employee) being from 0.12 to 1, to 1.5 to 1.

Watts talked about how these wide variations -- which she said did not correlate with size or prestige -- indicated how much more work there is to be done to make campuses more environmentally sound.

One audience member said that some of these problems may not be caused by colleges. Local zoning boards, for instance, may require parking spaces as a condition of approving new construction, leading colleges to create more parking and to encourage more drivers, the audience member said.

In an interview after the presentation, Watts said that she wasn't sure whether a group of public colleges would have responded the same way. "It's an open question."

Watts said that on many public campuses, she sees "pockets of sustainability," frequently in engineering schools. But she said that she sometimes sees campuswide commitment, and cited the University of New Hampshire as an example.