Problem: The theater building engineer reported occasional thermal discomfort complaints during performances before a full house.
Approach: CZ assessed thermal loads and outside air requirements for a full house, and conducted a detailed as-is HVAC system design review, Building Automation System (BAS) data trend review, temperature and relative humidity data logging during fall season performances, as well as partial air flow measurements from ceiling supply air terminals. Additionally, we constructed a Computational Fluid Dynamics (CFD) model of the air distribution within the theater operating at design conditions.
|Click to see videos of our CFD Analysis for Lila Cockrell Theatre.|
Findings: We found that the overall HVAC system had sufficient cooling capacity but insufficient outdoor air capacity. The BAS provided erroneous and inconsistent data and could benefit from a complete recommissioning, including sensors and actuators, to bring them back to their original design intent and operation levels. Both temperature and relative humidity were not found to be unusual for the performances monitored. Some of the ceiling supply terminals did not provide the designed air flow rate. Additionally, a fabric duct air distribution system on the side walls of the theater seemed sub-optimal, and we suspected this to further contribute to likely air distribution issues. However, the CFD model suggested that the theater was actually being flooded well with cold air, and that even the fabric ducts were contributing, despite being located in close proximity to return air grilles.
Results: The recommendations included recommissioning of the BAS, re-testing and re-balancing of all air handlers and air terminals, and a repeat of data logging during summer season performances to ensure that worst conditions were being captured. We predicted that any thermal discomfort complaints would be resolved by simply bringing the HVAC system back to design conditions, from which it had deviated over the years. Such is observed frequently and due to wear and tear as well as overriding of automatic with manual set-points.