Efficiently ventilating cinemas has long been an issue for HVAC professionals and cinema owners alike. High outside air loads, stringent acoustic requirements, close temperature control and rapid occupancy changes often force designers to move away from conventional packaged systems.
Air Change equipment, with its internationally patented heat exchanger technology, has been proving its success in cinemas and high occupancy facilities Australia-wide since the mid 2000s.
The company’s heat recovery systems are designed and manufactured in Sydney and continue to utilise the latest technology to ensure optimal energy efficiency for its customers, while providing superior indoor air quality for occupants.
During the design and construction of the Limelight Cinemas in Ipswich at the Riverlink Shopping Centre in 2013, the design consultants ADG Engineers worked with Air Change engineers to create a customised solution that would maintain comfort and efficiency during the frequent occupancy peaks and troughs that occur within a cinema complex.
Together with the high efficiency proprietary heat exchangers, a three-stage 30-70-100 per cent compressor arrangement was used to provide close temperature control and dehumidification under all conditions.
Air Change Queensland manager Mark Hams said it wasn't just about meeting the regulatory fresh air requirements.
“One of the keys to better indoor air quality is the use of high volumes of outdoor air, eliminating the stale air which is often laden with air-borne contaminants such as body odour, bacteria, fungal spores and dust,” he said.
“Air Change products effectively eliminate these hidden pollutants, whilst utilising the energy held in the spill air to pre-cool fresh outdoor air, without the risk of cross contamination.”
The Air Change counter-flow air to air heat exchanger features two separate air paths that allow energy transfer without contaminating the outdoor air. “In this application the heat exchangers have allowed plant capacities to be reduced from between 40 to 50 per cent, equating to a total plant capacity saving of 170 kWr,” according to Hams.
High indoor air quality is able to be maintained by monitoring CO2 levels in the respective cinemas and running higher levels of outdoor air during peak occupancy to ensure a high quality cinematic experience for all patrons.
The Air Change units have the capability to run at up to 80 per cent outside air in Energy Recovery mode and the provision for 100 per cent Outside Air during Economy Cycle on larger units.
With six cinemas onsite, varying between 100 and 330 seat capacities, a variety of Air Change units were selected to cope with the differing heat loads – with units from 23 to 70 kWr in capacity.
The six unit air conditioning system allows the cinemas to vary the flow of fresh air and provide high levels of oxygen to the space.
Once the systems were selected and air quality requirements met, work began to ensure that the sounds levels in the theatres emitted by the air conditioning system were within the nominated noise criterion of NR 25.
This is 10-15 dB(A) quieter than the requirements for a typical office space. Strict noise criteria are required for cinemas to ensure that air noise or plant breakout noise does not interfere with the acoustics of the theatre and detract from the cinematic experience. Detailed fan selections were completed and compiled along with breakout sound data for the Air Change units. This data was then forwarded to the Acoustic Engineer for assessment.
ADG Engineers then took on board recommendations from the Acoustic Consultant and set out to carefully design the air distribution system and select attenuators to ensure that the acoustic requirement of NR 25 was satisfied.
The rooftop package units supplied by Air Change for Limelight cinemas were designed and built in their manufacturing facility in Sydney.
The six Rooftop Package units were purpose built to suit the theatre capacity and included two 23kW units, two 32kW units, one 60kW unit and one 70kW RTP. They included EC plug fans for increased energy efficiency, CO2 control and the largest two units utilised economy cycle to further reduce the energy required to condition the facility.
Commissioning assistance was also provided by the manufacturer to ensure that the units were set up in line with the intent of the design and standard manufacturer’s recommendations.