Thermal comfort aspects of cold air distribution system

An ice storage system can supply chilled water at approximately 0°C (32°F) to 4°C (39.2°F) to air-handling units. A cold-air distribution system supplies air between 8°C (46.4°F) and 10°C (50°F), which is cooled with the chilled water from an ice storage tank, directly into an air-conditioned space. The system allows large temperature differentials, enabling a considerable reduction in initial and running costs for distribution equipment such as fans and air-handling units. However, there are some concerns about the direct supply of cold air to occupied zones. Draft is one of the major concerns with direct cold air diffusion. The authors conducted draft evaluation experiments with a thermal manikin and also conducted experiments with subjects to prove the manikin results, especially under the best and worst diffusion conditions, based on the manikin experiments. The results showed that air cooled to 7°C (44.6°F) and 8°C (46.4°F) caused no draft that annoyed occupants when used with conventional circular ceiling diffusers.