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A facility at Iowa State University was constructed to evaluate the impact diet modification has on air emissions. The facility was designed and constructed to have the unique ability to investigate emissions from cattle, poultry and swine by incorporating interchangeable penning and watering systems. Excreta and manure volumes can be measured for group-housed animals. Gas emissions are determined by measuring airflow rates through each of the eight animal chambers and multiplying airflow by the change in contaminate concentration between the effluent and influent ventilation air for each chamber. Chambers are monitored sequentially, for 15 min each, with incoming air gas concentrations subtracted from chamber gas concentrations, providing 10-11 observations per chamber each day. Each chamber is independently heated or air conditioned based on a temperature setpoint, with air delivered from a central plenum into chamber-specific variable air volume boxes. Data acquisition is coordinated through software control, including an emergency alarm system should ventilation problems arise. Findings from the first swine study conducted in the facility indicate that this facility can discriminate between emissions from animals fed diets that are modified to reduce nutrient excretions while maintaining animal performance. A brief laying hen study followed to challenge the sensitivity of the system to small dietary changes.