Volume I 
ventilation to the microenvironment. This may be a reasonable assumption when cages have a 
top of wire rods or mesh. However, several studies have shown that covering cages with filter 
tops provides a protective barrier for rodents and reduces airborne infections and diseases, 
especially neonatal diarrhea, but can result in significant differences in microenvironmental 
conditions due to changes in air movement caused by the cage cover. 
Exactly how well or how poorly these filter top cages are ventilated in a room was not known 
until this research was completed. Previously published literature only identifies the relative 
performance of different types of tops. Although some data exist on the flow resistance of filter 
material, determining how and how much air gets in and out of the cages was vital for this study. 
This research has quantitatively measured the ventilation performance of a specific filter top 
microisolator cage for different airflow conditions. It investigated the airflow between the upper 
and lower moldings, taking into consideration leakage that occurs due to the fact that the top sits 
loosely on the bottom, compared with the ventilation through the filter top itself. A wind tunnel 
was designed and tests were performed to compare the ventilation of single cages to two cages 
standing next to one another, closely representing a cage sitting on a rack in an animal facility 
room. CFD models of a cage in the wind tunnel, various orientations of a cage in the wind 
tunnel, and airflow velocities were constructed and run. These showed an excellent agreement 
between the simulation results and the measured values, confirming that the cage model used in 
the room simulations was representative of a microisolator cage. 
In order to analyze the ventilation performance of different laboratory animal research facilities, 
numerical methods based on computational fluid dynamics were used to create computer 
simulations of more than 100 different room configurations. The performance of this approach 
was successfully verified by comparison with experimental measurements in a typical laboratory. 
A total of 12.9 million experimental data values were collected in an empty (except for the 
ventilation system) laboratory scenario, while 0.66 million data values were collected in a 
populated (included simulated animal racks) laboratory. The comparison between the numerical 
and experimental data was particularly good for temperature and gas concentrations. In 
particular, the average error between the experimental and computational temperature in the 
laboratory was 14.36 percent, while the equivalent value for gas concentrations was 14.50 
percent. The low air velocities proved more difficult to measure, which further demonstrated the 
need for computational techniques that are not limited by measurement uncertainties encountered 
at low velocities. To investigate the relationships between room configuration parameters and the 
room and cage environments within laboratory animal research facilities, the following 
parameters were varied: 
• Supply air diffuser type and orientation, and air temperature and moisture content; 
• Room ventilation rate; 
• Exhaust location and number; 
• Room pressurization; 
• Rack layout and cage density; 
• Change station location, design, and status; 
