The correct installation of an air conditioning system in a cinema or a theater is a fundamental aspect to offer comfort to the spectators. by Duván Chaverra Agudelo
Movie theaters or theaters are suitable spaces to receive a considerable number of people who gather to enjoy a show, either through a giant screen or with a live musical or theatrical presentation. That is why one of the most important aspects and that must be taken into account from the design stage is the air conditioning. Julio Londoño, product manager of Belimo, commented on the matter that "normally these enclosures have acoustic insulation that also works very well as thermal insulation, and when the room is full of people the caloric load is quite high, if the space is not conditioned it would be very uncomfortable for the spectators". Another of our guests is the engineer Iván Ramírez, operational director of the northern zone of Servipáramo, who described that air conditioning is an element of vital importance and that incorporating an air conditioning concept that communicates in the best way with all the previous characteristics is a challenge from the technical-economic point of view". "Theaters are places that due to their condition use construction systems that make them have special acoustics. For this, the dimensions of the enclosure are taken into account, so then the capacity of the same and the reverberation time are defined. As far as sound is concerned, the biggest transmitting element is the ceiling, this explains the reason for the height and the reason for the location of sound deflector plates behind the stage, on the sides and on the ceiling. The floor itself is a key element, as it follows the curve of a logarithmic spiral that has two important connotations: to guarantee the optimal visual line, and to avoid the phenomenon of diffraction in the head of the public, "said the engineer Ramírez. The air conditioning design
Here, as in most projects, the design must be planned thinking about the comfort of people, but it must also be taken into account that this type of public will be sitting most of the time watching an event. Julio Londoño recommends considering during the design stage ventilation and air renewal systems: ducts or ventilation shafts. "The air distribution system must be very quiet, so the architectural design must consider the ductwork and the plenum of return or distribution. In the distribution of air should be used diffusers that avoid as much as possible the jets of direct air on people, in places where people move this is not a problem, but for an audience that is going to be sitting in one place for a certain time these direct jets of air are very annoying. " For his part, Iván Ramírez believes that systems such as air handlers are the most appropriate option to control large volumes of air, which can be cooled by water or by water-condensed package systems. "The large volumes of air to be handled involve large ducts, which when over passing the 84' must be manufactured in cold rolled sheet, this sheet, according to the standard, must have a thickness ranging from 1.15 to 1.20 mm, and a weight of 9.5 kg / mts2, this makes these duct systems something complex to install, because due to the weight of the same and the complexity of the floor and the height, versatile fastening systems should be considered, "explained the representative of Servipáramo. Another option proposed by Ivan is to use certified materials, such as expanded polyurethane sheets, with densities above 35 kgm/mts2. "These sheets comply with the self-supporting capacity necessary for the manufacture of large ducts, as well as the thermal resistance to avoid losses in air transport, they also have, like the fiber sheet, a vapor barrier that prevents the passage of moisture that could be generated in cases where temperatures below the dew point are reached."
Meanwhile, Julio Londoño thinks that ice water systems are highly recommended for this kind of installation. "It is important that the equipment behaves very well at partial loads when the room is with low occupancy as well as at high loads when the room is full; the systems that best meet this requirement are ice water systems with modulating valves. If package computers are to be used, they must be able to work in stages or have several in sequence. In wet areas, the equipment must be able to dehumidify all the time, if package equipment is used it must be underdimented so that the compressor operates all the time and does not stop dehumidifying." Ramírez adds in this regard that "systems with water chillers, or systems with water condensed equipment, also allow centralizing access to equipment, this easy access allows optimal hydraulic and air balancing in the ducts, and if there are space limitations, the technical rooms could be optimized using vertical type pumps; in the market there are compact systems that include in a single element the filter, the valve that prevents the return, and the balancing valve, all this minimizes the space if it is considered, compared to conventional horizontal pumps". Maintenance
As in any installation, maintenance is key to constantly verify that the equipment is working correctly and that it does not present any failure. In the case of systems for movie theaters or theaters, it is best to verify that the filters are not dirty. "Air cleanliness is very important, so more attention should be paid to cleaning the filters. It is advisable to use differential pressure switches to detect when the filters have reached a level of dirt such that it requires replacing or cleaning them, preferably monitored by an automation system," explained Londoño. Iván Ramírez indicated that in addition to the monitoring that must be done to the filters supported by pressure drop detection systems, "the cold water system implies the periodic review of the control valves, the cooler is always advisable to be intervened by the supplier, in this way the guarantee is preserved. The pumps must be lubricated keeping the supplier's suggestions, in terms of the brand of the grease and the frequency. The big drawback is the elements located at high altitude, such as the grids, diffusers and terminal elements in the ducts, their cleanliness guarantees the quality of the air that is distributed in the enclosure. In case of using water-condensed systems, in-line systems are recommended, which are easily sustainable against maintenance with chemicals." Ideal temperature
A cinema or theatre must have the ability to regulate the ideal temperature according to the size of the room and the number of people it will receive per performance, as well as the climate of the region. Experts recommend that the ideal temperature is at an average of 22°C. Representative Belimo explained that "the important thing is to keep people comfortable at the temperature that makes them feel at ease (this number varies according to the region; the people of the coast have a greater setpoint than the people of the mountains) and the setpoint is the same as for any other area. The fact that the occupants are seated must be considered, so as important as temperature control is to ensure that the room has the renewal air, or air changes required according to the occupation. Much better if occupancy is monitored with CO2 sensors and the automation system controls the level of renewal air based on this reading." For his part, Iván Ramírez concludes with the following opinion: "The comfort temperature for this type of enclosure is an average between 21 and 23 degrees Celsius, but it is important to take into account the phenomenon of air absorption, so that in this way it does not affect the performance of the design of the acoustic system. There are formulas that explain the relationship of humidity and temperature with the ability of air to transport sound and absorb it. In conclusion, the request of the expert in the field should be taken into consideration." To highlight
The usefulness of filters
The filters, capable of trapping up to 90% of the particles suspended in the air, are suitable to protect systems and people from phenomena such as moisture that causes bacteria. The filters, added to the minimum air to be replenished, are responsible for the environment to be air-conditioned to generate adequate comfort. These filters are classified as efficiency 12 to 14, MERV classification number, which indicates how effective they are when retaining particles, the aforementioned have an efficiency of up to 90%. Easy access to the review of this equipment ensures that these filters are kept clean and can be changed when necessary. If the outside air is humid, it is vital that the equipment has the ability to dehumidify the injection air, even consider conditioning the outside air using 100% outdoor air equipment (Make up air units) to supply dry renewal air to the equipment in the rooms. The distribution of the air must avoid condensation in the areas as much as possible to avoid the growth of mold and bacteria.
