Robert Dean describes himself as an academic architect of the old school, with an intimate knowledge of the history of architecture and a willingness to use history skillfully and respectfully in the design of each building project.  Mr. Dean, a graduate of Columbia University's Architecture School, has practiced his art from Virginia to New England although his firm, Robert Dean Architects, is based in New Canaan, Connecticut and has become known for creating some of Fairfield County's memorable residences.   Along with new residences, a number of his projects have involved working with existing older houses of distinguished design or notable historical value.