Draught sensation assessment in an occupied space heated by stratified ventilation system: Attachment ventilation with relayed fans

Abstract The application of stratified ventilation systems for winter heating brings out the doubt of draught issues on the lower part of body. The purpose of this study is to quantify the thermal sensation and air movement acceptability of occupants in an occupied space with the stratified convective–heating systems. Twenty subjects participated in eighteen trials and they were blinded to test conditions. Three air temperatures of 20.5, 21.5 and 23.0 °C and three local air speeds of 0.4, 0.6 and 0.8 m/s are chosen as the examined parameters in the warm air lake. Two shoe types of low–cut and high–top being considered for providing different protection on ankles were also used. Local and overall thermal sensation, thermal comfort and acceptability, air movement acceptability, the preference on thermal environment and air movement were collected. Perceived indoor air quality and dry eye symptoms were also acquired. Results demonstrated that subjects were sensitive to local air movement at both calves and ankles rather than the ankles only. Low air temperature ( 0.4 m/s) in warm air lake may cause 20–65% of subjects to complain about the unacceptable air movement. High–top shoes could increase the air movement acceptability on ankles by 15% but little effects on calves were discovered. Only 7% of the subjects reported eye dryness in all tested conditions and almost all subjects could accept the indoor air quality. This work may help improve the understanding of draught sensation on lower body parts in an occupied space with the stratified convective–heating system.