Not every building can be easily modified or adapted to immune building technologies. Buildings that do not meet current ASHRAE Standard 62-1999 guidelines for minimum ventilation rates may not be suitable candidates for immunization. A complete review of the building ventilation system is conducted to determine the best implementation possible and any necessary changes that might be required to bring operating conditions into conformance with ASHRAE standards. Modifications may include replacement of existing filters, location of UVGI systems in the air handling unit or ductwork, installation of local recirculation systems or upper air UVGI systems where necessary or when requested, resizing of fan motors to meet the power or airflow
requirement when new filters are installed, and a general review of the airflow characteristics throughout the building.