Therefore, precooling is not usually applicable, except for the first matinee. Seating is well-defined, and lights are dimmed when the movies begin. Low load performance is quite important since theaters often operate at low occupancy. Lobbies and exit passages are typically designed for 20 to 30 sq ft per person. Projection booths are a special design problem.
Heat sources are the projector light, sound equipment, and dimming equipment are significant.
Although some may be air-conditioned, most operate with a negative pressure, simply exhausting theater air through the projection room and out through the projector housing. In some cases, filtered supply air is used to minimize soiling the lenses.