Zhang et al. (1992) describe a survey of U.S. facilities that house laboratory rats.
Data are needed to quantify laboratory animal environmental conditions so as to improve animal well-being, facility design, and energy efficiency. Seven laboratory rat facilities at a U.S. university were surveyed. Temperature, humidity, air velocity, and ammonia levels in rooms and selected cages within the rooms were measured and analyzed...Ventilation recommendations are based on room air exchanges, but air exchanges in the animals' microenvironments can be inadequate or excessive depending on the cage and facility design. The room air-diffusing system, cage type, and other room characteristics generally may be more important than room air exchanges in their impact on the animals' microenvironmental conditions…The principal index for quality animal microenvironments —ammonia level—varied widely among cages even though room air exchange rates were similar…microenvironmental conditions can be improved by increasing the cage ventilation rates. Achieving this, however, was more dependent on cage design, room ventilation system design, and animal management practices than on room air exchanges.
Maghirang et al, (1996) suggests three basic ventilation strategies for animal facilities:
Further, Maghirang et al, (1996) state that in animal facilities, the room air distribution system should:
In their work, Maghirang et al, (1996) identified the most important design factors in animal facility design:
In a study by, Riskowski, et al, (1996), cage type was also identified as an important factor in determining ventilation rate in an animal facility.
Research by Memarzadeh (1999) shows that increasing room ventilation does not have a significant effect on cage ventilation. Accordingly, "Since air change rates in excess of 10 ACH do not materially improve environmental conditions within cages, more care should be given to proper cage arrangement and air distribution." [Memarzadeh, 1999]