Environmental Control Strategies in Multipurpose Halls for Various Activities

Multipurpose Hall Environment Control

Multipurpose Halls are provided in modern commercial buildings for variety of purposes. These may also be purpose built independent facilities for large gatherings. When combined with office buildings, it is used as Training Center, Lecture Hall or recreational activities. Independent theaters are used for art performances, dramas, dances and public gatherings.

When people are seated in a hall at rest, watching or listening, their body losses and heat generation is different from active people. With heavy activities like indoor games, participants have high rates of metabolic activities which increase latent heat loads. Two distinct areas based on activity levels are created in such a facility. Environment control of these two zones is treated likewise. Air Conditioning Unit coil conditions for control of thermal comfort is different for both of these areas. Due to these reasons, Air Handling Units for stage and heavy activity areas is separate from public seated areas AHU.

High fresh air flow is required to maintain indoor environment control. More people are seated per unit of floor area. High density requires large quantity of outside air. Exhaust air from hall is used to pretreat fresh air intake. This procedure pretempers ambient air with building exhausts. Load on Air Conditioning plant is reduced. Plant energy consumption is saved by this procedure. Multipurpose Halls are fit case for energy recovery systems. Recovery wheels are used for this purpose.

Lighting systems in Halls and Performing Studios generate considerable heat. This heat rises above close to ceiling level. Air distribution system is arranged so as not to disturb this stratified air. Conditioned air is directed towards occupants. This is not allowed to mix with stratified zone. For this purpose, proper location and type of air devices are very important.

Displacement ventilation system is another option for seated areas. Air Conditioning equipments are located below seating areas. Air is provided to each occupant close to seating areas from below. Floor openings are used for this purpose. This arrangement is configured with seating arrangement. Combine solutions are available for public seating and air delivery which reduce ducted runs and noise levels. Acoustic levels in theaters are kept low for proper environment control system. Equipments are located away from seating areas. Duct liners are used to minimize chances of noise transmission to halls. Displacement ventilation system uses low volumes of air. Low volumes are associated with smaller duct sizes and hence better noise control.

Air Conditioning loads for facility halls is not a continuous load like office building or hotel loads. This is instant load.  Most of the time demand occurs after regular working hours. Even during working hours, this type of facility is used for few hours of operation. In order to reduce main cooling/heating equipment size, thermal storage is used. During off peak hours thermal energy is stored, it is used when demand occurs. This system saves initial equipment costs. System operation becomes reliable and fail safe when few pumps are required to provide system operation in case of storage.   

Fresh air quantities can be reduced by employing demand control ventilation. Instead of constant outdoor air equal to full seating capacity of the hall, ventilation air is modulated as per demand. Co2 levels are monitored. Set differential of Co2 is maintained inside to provide necessary ventilation rates.