In a large theater, keeping spectators comfortable can be a big challenge, but the possibilities are endless.
By: Jorge Gaitán*
Ventilation needs vary constantly, depending on whether the film being released is a box office success or failure, or whether it is a morning or evening performance. The more people in the theater, the more complex it will be to provide acceptable indoor air quality (CAI).
People, and the CO2 they exhale, have a real impact on indoor air quality; the larger the audience, the more fresh air is needed to fix this problem. Too much fresh air raises heating and cooling costs, which drives up the bill for electricity consumption.
Need versus costs
Today, numerous major theater chains, large retail chains, among other companies, keep their customers comfortable with an Automatic Ventilation Controller (CAV), which regulates the amount of fresh air that enters, according to the number of occupants of a place.
Fresh air and carbon dioxide
The automatic ventilation control estimates the number of people in the building based on current carbon dioxide levels (using a CO2 sensor) and then sends a signal to the roof controller.
To reduce the need for mechanical cooling, a gear-driven saver is used that regulates according to the external air temperature. The controller interrupts the external air regulator according to CO2 levels, moving it to the proper position according to the number of occupants. In a movie theater, for example, the regulator will open to the maximum when the room is completely crowded, but will remain in the minimum position in a morning function where there is almost no one.
Interrupting the external air regulator is only possible with a modulating sparing regulator; otherwise, someone would have to be sent to the roof every time the CO2 measurement changed.
A simple and efficient system
Choosing a CAV system with built-in controls makes it easier to use. A signal is sent according to the CO2 measurement, the position of the regulator is interrupted to reduce energy consumption and ensure a comfortable and healthy environment. The user-friendly design allows theatre managers or storage managers to monitor CO2 levels as well as other information, including alarms, on site or from a remote location.
Gear-driven savers require less maintenance as they do not need covers and require fewer adjustments. This helps ensure that an adequate amount of external fresh air is always available to maintain comfort and reduce energy consumption.
Business Benefits
Theaters aren't the only businesses that reap tangible benefits from improving indoor air quality. A low CAI can lead to different problems, from undesirable odors to the so-called "sick building syndrome". Not only can it make people uncomfortable, but it can also make them sick. The highest standard in maintaining air quality through ventilation is ASHRAE (American Society of Refrigeration and Air Conditioning Engineers) 62-2001.
The ASHRAE standard on Ventilation for Acceptable Internal Air Quality prescribes the necessary ranges of ventilation to increase comfort and reduce energy consumption, as well as concomitant liability risks. This standard is incorporated into many building codes to promote best practices regarding ventilation to maintain air quality.
* Lennox Industries, Inc.
