Reductions in energy consumption and carbon emission might be achieved by elevating indoor air temperatures in air-conditioned buildings. Guidelines for various elevated room temperatures in summer have been issued by several governments in East Asia. To accommodate the warm indoor conditions, a novel air distribution solution, stratum ventilation was proposed for the application in small- to medium-sized rooms. Previous studies have proved that stratum ventilation is capable of providing satisfactory thermal comfort, good inhaled air quality with substantial year-round energy saving. However, the knowledge on this new air distribution is still limited, such as the unique characteristics of air distribution and thermal environment. This dissertation employs experimental and numerical methods to study flow characteristics and thermal environment under stratum ventilation thoroughly. The major works include: (a) airflow characteristics and performance of stratum ventilation in a multi-occupant room; (b) characterizing the interaction between the human body and stratum-ventilated airflow; (c) uniformity of stratum-ventilated thermal environment; (d) subjective investigation into local thermal discomfort due to draft; and (e) technical feasibility of stratum ventilation for multiple rows of occupants. Room occupants’ comfort and health are affected by the airflows. Nevertheless, they themselves also play an important role in indoor air distribution. The detailed measurements of air velocity and temperature are conducted in a stratum-ventilated room with multiple thermal manikins. For the purpose of comparison, the measurements are also carried out under mixing ventilation and displacement ventilation. The results show that the airflow characteristics among mixing ventilation, displacement ventilation and stratum ventilation are different. The turbulent fluctuation is enhanced in the room with multiple thermal manikins due to thermal buoyancy and airflow mixing effect. For stratum ventilation, supply air temperature is necessarily higher to achieve general thermal comfort with low draft risk and the cooling efficiency is higher as compared with mixing ventilation and displacement ventilation. Following the experiment, the computational fluid dynamics (CFD) simulations reveal that stratum ventilation can provide good inhaled air quality in terms of CO2 level and local mean age of air at the breathing zone. Using simplified thermal manikin to resemble the human body as the flow obstacle and/or free convective heat source effectively, interaction between the human body and stratum-ventilated airflow is experimentally investigated. The manikin forms a local blockage effect, but the supply airflow can flow over and around it. The body heat from the manikin enhances the supply air jet penetration and increases air temperature at the downstream of the manikin. Elevating the supply airflow rate from 7 to 15 air changes per hour (ACH) varies the downstream airflow pattern dramatically, from an uprising flow induced by body heat to a jet-dominated flow. Data from three human test series are used to evaluate uniformity of stratum-ventilated thermal environment. An air diffusion performance index (ADPI) of at least 80% is achieved for most cases studied, indicating that the cooling effect coupled by air velocity and temperature in the occupied zone is reasonably uniform. The subjective evaluations of thermal sensation show that thermal sensations of the subjects under stratum ventilation are also uniform. Both the objective measurements and subjective assessments suggest that the thermal environment in the occupied zone of a stratum-ventilated room is uniform. Subjective investigations into thermal comfort with a focus on draft are conducted under various combinations of room temperatures and supply airflow rates. The room temperature has a great impact on thermal comfort, whereas the effect of the supply airflow rate on thermal comfort depends on the room temperature. At a slightly cool sensation at a room temperature of 24°C, the ratings of draft frequently reported at the uncovered body segments are high with elevation of the supply airflow rate, but a warm sensation at a room temperature of 29°C increases the percentage dissatisfied due to insufficient air movement and decreases the acceptability of perceived air quality (PAQ). However, at least 80% occupant acceptability including thermal comfort and PAQ, and the draft ratings below 20% are obtained at the thermal neutral temperature of around 27°C. These results show that stratum ventilation provides a comfortable environment, so that people can have the feeling of "cool head and warm feet", with low draft risk at a room temperature up to about 27°C. Theoretical analysis, human subject tests and CFD simulations are carried out to explore the technical feasibility of stratum ventilation for multiple rows of occupants. All the results show that stratum ventilation can be used for a room with occupants in multiple rows. The number of rows depends on the type and size of a room. This is mainly because the cool supply air can flow over and around the front-row occupants to reach the back rows even though they establish a local blocking effect to the supply airflows. Therefore, it is reasonable to expect that with properly designed supply parameters, stratum ventilation can be applied in a room with multiple rows of occupants.