Metropolis has an interview up with Lisa Fay Matthiessen and Peter Morris, of the cost-management firm Davis Langdon, who just released a report "Costing Green: A Comprehensive Cost Database and Budgeting Methodology" (PDF) which concludes that meeting green building standards costs the same, or only slightly more, than conventional building practices, once the expertise is available to make smart choices:
"What characteristics do some of the most successful LEED projects share?"
"We found successful projects--ones that achieve a high LEED score and stay within their original budgets--are ones where the design team sits down with the owner right at the beginning to talk about sustainable design and clarify goals. [That way] everyone on the team has some input. The most successful projects have a very integrated process. The projects where its not working as well is where some member of the design team takes on [the LEED elements], but is doing it separately from the rest of the team."