Volume I - Section I - Introduction 
Page I - 1 
1.0 INTRODUCTION 
1.1 Objectives 
This document describes a research program undertaken by the National Institutes of Health, 
Office of Research Services, Division of Engineering Services. The work was carried out in 
collaboration with the University of Illinois Bioenvironmental Engineering Research Laboratory 
(BERL) and Flomerics Inc. 
The hypothesis of this research was that the room ventilation parameters, which include room 
ventilation rate, diffuser type, diffuser location, number of exhausts, exhausts location, cage 
density, changing station location, changing station status (on/off), room size, cage rack 
arrangement, and room pressurization, affect both room (macro) and cage (micro) environment 
for laboratory animal research facilities. 
In order to develop relationships between micro- and macroenvironmental conditions and to 
better determine ventilation system designs that provide appropriate micro- and 
macroenvironments, the following objectives were set: 
1. Conduct a study to determine typical mass generation rates of C0 2 , H 2 0, and NH 3 , and 
consumption of 0 2i with groups of mice in shoebox cages with bedding at different room 
air relative humidities using open-system calorimeters with precisely controlled fresh air 
exchange rates. 
2. Create and measure various airflows within a known mouse cage in such a manner as to 
lay the groundwork for determining the boundary conditions for the computational fluid 
dynamics (CFD) analysis of the cage. Cage boundary conditions include resistance and 
coefficient of loss created by both the cage top and the surrounding edge on which the 
cage top sits. The tracer gas method using 1 L/min, and 100 mL/min injection rate for 
measuring the airflows within the cage was used. Comparison were conducted between 
tracer gas types C0 2 vs. SF6, as well as changing airflow measurement techniques using a 
constant injection rate and decay methods. 
3. Obtain data in an empty room as well as a room with racks, cages, and simulated animals 
to verify the accuracy of CFD. Room air velocity, temperature, and C0 2 concentration 
patterns were used throughout the room for verification of CFD model predictions. 
4. Utilize over 500 CFD simulations to establish a relationship between micro- and 
macroenvironments by changing room ventilation rate, diffuser type, diffuser location, 
number of exhausts, exhausts location, cage density, changing station location, changing 
