University of Georgia, Georgia Museum of Art Humidity Study, Athens, GA
The Georgia Museum of Art is responsible for the storage and display of priceless pieces from numerous time periods and locations. The University of Georgia Facilities Management Division, UGA FMD, contracted with SETTY, to provide a humidification study on a series of air handling units and steam humidification systems which provide conditioned air to a tightly controlled museum and archival vault/storage room. The scope of the study was to determine the cause of the humidification and dehumidification problems; and provide a recommended design and repair concept that would solve water leakage issues, gain better system control of temperature and humidity levels in critical spaces, and manage building alarms.
The mechanical systems were essentially unchanged from the original design from the 1994 construction. Chilled water multizone units, along with their associated zone ductwork, electric reheat coils, and steam dispersion tube humidifiers were the system components responsible for keeping these critical spaces at temperature and humidity setpoints. Operations and Maintenance was being called out on a regular basis to attempt to repair or address the following items:
1. Water leaking from zone ductwork in the third-floor mechanical room which house the multizone units.
2. Low humidity alarms in galleries and vault/storage rooms during heating season.
3. High humidity alarms in galleries and vault/storage rooms during the cooling season.
Operations and Maintenance desired to solve these issues with identifying items that should be replaced, redesigned, or revised to allow the existing chilled water multizone units to function as designed to control temperature and humidity setpoint.
SETTY’s team approached the project with a detailed survey of existing equipment, a thorough review of the as programmed sequence of operations, and a review of the based building design to understand how the systems were intended to operate. SETTY made several site visits to survey existing systems, witness pre-TAB testing verification for airflows, and system temperatures and pressures; and to conduct a detailed review of the controls system.
The investigation of the system led to unexpected findings such as; a chilled water cooling coil that was not designed to provide proper dehumidification, gross amounts of outside air (Nearly 175% of design) being drawn into the system due to a poor outside air plenum construction and a bad airflow monitoring station location, and substandard steam dispersion tubes that were field fabricated by the contractor and did not possess specific dispersion nozzles to promote steam atomization and absorption.
SETTY’s recommendations and resultant design documents put forth the following measures to remedy the problems that were discovered: replacement steam dispersion tubes, rebuilt outside air plenums to promote better airflow readings, re-balanced zone dampers, a new cooling coil sized for adequate dehumidification during peak periods, and new steam control valves sized for real steam demands. Due the space constraints of the mechanical rooms, SETTY assembled the existing mechanical room layout in Revit. This helped demonstrate to the client that the ductwork and equipment modifications being proposed were feasibly constructible.