Objective and subjective assessment of thermal comfort in a room served by a novel enhanced displacement ventilation system

Abstract

This dissertation evaluates the problems of Displacement Ventilation (DV) system and proposes an enhanced DV system. The enhanced DV system consists of a newly-developed chair with 4 fans mounted at each corner and the fans are free to move at three different angles, 0oC, 30oC and 60oC.

Objective measurements and subjective assessments were conducted in the Indoor Air Quality Chamber of National University of Singapore which typically characterises the office situation in Singapore. The air temperature gradients in small office rooms served by the newly-developed enhanced DV system as well as the acceptability of the system by the tropical acclimatised subjects were examined through varying the supply air temperature and the fan angles.

Data for this dissertation was obtained through experiments, questionnaires, previous research articles and online report resources. A sample of 32 undergraduates was employed for objective measurements and subjective assessments.

The idea of having adjustable fans at different angle concluded that enhanced DV system is able to satisfy majority of the occupants within the same space when there is personal control on the thermal conditions. The fans employed helps to achieve good stratification which brings about good air quality at the occupied zone. However, the fans were unable to reduce draft sensation as subjects were prone to draft at waist. Thus, greater control in adjusting subjects’ preferred speed will help to achieve their ideal thermal comfort condition. Another limitation of this experiment study is the arrangement of the fans where it can be further improvised to prevent draft at waist of the subjects. It can be suggested that the fans mounted at each corner of the chair can be powered by solar panels instead of DC power supply so as to achieve the idea of energy-saving. . This is an attractive option as there will be a further reduction in energy consumption of the newly-developed enhanced DV system.