Volume I 
Page xix 
FOREWORD 
Laboratory animal ventilation should balance air quality, animal comfort, and energy efficiency 
to provide cage environments that optimize animal welfare and research efficiency. Conditions 
that optimize animal welfare automatically tend to improve research efficiency because it is 
especially important in research to minimize unintended stress factors. Additionally, the 
laboratory animal ventilation system should provide a healthy and pleasant environment for 
researchers and animal caregivers. 
This work examines the relationship between the air quality in the macro- (room) and micro- 
(cage) environments in animal facilities. It provides the first systematic study of the ventilation 
of the macro- and microenvironments simultaneously. It demonstrates only a weak link between 
the room ventilation and the conditions inside the microisolator cages. Further, it shows that 
improvements in the room conditions may harm cage ventilation. For example, low level 
exhausts can produce 27 percent lower CO 2 concentrations in cages while raising it to over 70 
percent in rooms. 
In order to carry out the research, extensive experimental data was collected to provide an 
accurate basis for the behavior of mice in terms of heat, carbon dioxide, and ammonia 
production. They are necessary inputs to the computational fluid dynamics (CFD) simulations. In 
addition to providing specific data for a particular strain of mouse and a type of bedding, this 
document details measurements and parameters for experimental procedures that can be used for 
other species as well. 
It was also necessary to carry out numerous measurements to calibrate the CFD model of the 
cage, particularly to evaluate the resistance of the filter material in the lid of the cage as well as 
to estimate the effects of any leakage where the bonnet top of the cage sits on the bottom of the 
cage. It was found that a significant amount of air did flow under the lips of the cages in the wind 
tunnel tests. The CFD model was modified to account for this. Without the experimental data it 
would have been impossible to carry out the CFD simulations with any confidence that the 
model of the cage really represented a typical microisolator cage. 
There was also some experimental work done to measure airflow in both empty and occupied 
rooms with racks of cages containing “dummy” mice that provided both heat and CO 2 gas. 
Unfortunately, the low velocities present in the test rooms made accurate measurement very 
difficult. The comparison between CFD and measurement did not meet our expectations, 
particularly for the empty room, which was further complicated by temperature variations in an 
apparently isothermal situation. 
While this document does not define a perfect animal facility it does demonstrate how given 
options can be chosen to influence the room and the cage. The results form a database of 
performance data for different configurations to which proposed designs can be compared. 
