Volume I 
Page xxi 
Why You Should Read and Refer to this Document 
A number of recent facilities have been built with high level exhaust systems. This happened as a 
result of publications that reported on studies that concentrated on the thermal ventilation 
efficiency of the macroenvironment. Those studies ignored the internal cage microenvironment. 
When the exhaust is placed at high level, it is easy to overlook the reduced cage ventilation 
efficiency for filter top cages. Designers, facility managers, and veterinarians should therefore 
refer to this document when they need to make an informed decision on the choice of exhaust 
location. 
This document also provides valuable information about ventilation rate per lOOg of stock and its 
relationship with bedding change frequency. Furthermore the research indicates our ability to 
reduce ammonia generation by raising temperatures. This may have energy efficiency benefits 
for rooms operating largely or exclusively on cooling, although consideration must be given to 
the relative humidity in those situations. 
