You could look into California College of the Arts - http://www.cca.edu/ - I visited the campus and talked with some faculty and students. They seem to have a real committment toward the sustainability approach. Their ID program has a course called “Energetics and Ecology in Design.” Yves Behar, the chair seems committed to sustainability.
Also maybe look into Western Washington University at Industrial Design | Engineering & Design | Western Washington University The ID program has a minor in sustainable design.
I’m just looking at programs myself. I get the impression that to move into sustainable design, you will need to be a pioneer and have to convince others of the value of this approach; I don’t see a lot of jobs advertised for sustainable design. Have you read Cradle to Cradle by William McDonough? Another good book is The Green Imperative by Papanek. Hope this helps some.