Finally, the results of Figs. 13 and 14 are combined in
Fig. 15 to present the vertical air temperature difference,
Dt , vs. the mean contaminant removal efficiency, 0.1r1.0 m
m0.1r1.1 m, when displacement ventilation and the cooled
ceiling are operated.
The low mean contaminant removal efficiencies indicating
good indoor air quality in the occupied zone are very
often associated with ‘high’ vertical air temperature differences,
pointing at a possible problem with thermal comfort.
The less critical variations are obviously the ones with
an entirely cooled ceiling. These arrangements provided
always acceptable vertical air temperature differences and
better air quality with displacement flow than with mixing
ventilation.
If it is not possible to cover the entire ceiling with
cooling panels or if the cooling panels cannot be distributed
regularly, the cooled ceiling area should be