The subject of this study is the design of cooled ceiling and displacement ventilation systems in buildings. States that good design of CC/DV systems can lead to better indoor air quality and thermal comfort in comparison to widely used VAV mixing systems. A key design parameter is the cooling load removed by the displacement ventilation. Due to a small vertical temperature gradient, a low DV has a positive effect on thermal comfort, but also has a negative effect on indoor air quality because of the increased mixing of room air. There is a negligible influence in the occupied zone of room height on temperature and contaminant profiles. Active contaminants are removed more effectively by these systems than passive contaminants. Condensation risk is however high on the ceiling panel. Startup and shutdown periods are danger times for condensation as is infiltrating outdoor humid air. The system's energy consumption reduction potential depends on the supply air temperature, outdoor airflow rate and cooling load. States that the development of design guidelines in necessary for these systems in US buildings.