The research method is primarily case-study based but sup - ported by interviews of practices and individuals. The cases are examined from four main perspectives: architectural design, sustainability, performance in use and occupant feedback. As a rule, the cases are selected because of their architectural interest as evidenced by prior publication in professional journals, the existence of innovative approaches to sustainable architecture, and the existence of post-occupancy evaluation. In reality, there is variability in the quality and quantity of data available on cases. In a few cases, the architectural interest of a project overrides data limitations, although in these cases the authors have sought to avoid drawing sweeping conclusions.