Too large vertical temperature gradient in the occupied zone is
one of the main thermal comfort issues in STARD systems [14].
In ASHRAE Standard 55-2004 [15], the temperature difference
between head and foot levels of occupant (thead–foot) is limited
to 3 ◦C. However, for the present cases, all the thead–foot obtained
at point A exceeded the limitation, while thead–foot obtained at
point B and point C were all in the accepted range, as shown in
Table 3. The reason is that the location of point A is too close to the
supply diffuser. This consists with the findings revealed by Lian and
Wang [16] that the distance between occupant and supply outlet
has a significantinfluence on thermal comfort.thead–foot increased
slightly when the height of return grille position decreased.
Fi