The first question that comes to mind is it a free standing home or a multiple family building such as a condominium or co-op.
- If it is a single family home the owner should be able to provide paperwork from the USGBC stating it has a LEED homes certification.
- If it is a multiple family building the building management would have the papers stating the building has been LEED certified.
You can also log into USGBC website and get a list of projectshere.
In either case being a LEED certified building is certainly something that can be verified.
For more information:
Read Andy Ault's Q&A "Why should I pay the extra money to certify my new home green?"