Volume I - Section III - Evaluation of Results and Recommendations 
Page III - 15 
The low CO 2 concentrations seem to be due to the higher flow around the cages. Figures 3.17 
and 3.18 show velocity vectors in a slice through the radial supply and the cage racks. For the 
ceiling level exhaust case (figure 3.17) the velocity vectors are barely visible around the cages, 
indicating very low flow. In figure 3.18 the low level exhausts case shows much larger velocity 
vectors representing much greater flow around the cages. This extra flow clearly helps ventilate 
the cages. 
The ceiling level exhausts produce the lowest levels of CO 2 for the radial and low induction 
diffusers in the room breathing zone. This appears to be caused by the main airflow going 
through the cages towards the side walls at this height, whereas in the other cases there is more 
air coming from the side walls into the central region. This can be seen in figures 3.17 and 3.18 
as well as in figures 3.19 and 3.20, which show the distribution of CO 2 concentration for the 
radial diffuser and ceiling and low level exhausts. 
Figure 3.17 Velocity Vectors through the Radial Diffuser with Ceiling Exhausts (base case) 
