Title 24 Requirements for Churches and Assembly Buildings
A place of worship is decided by its ventilation. Table 120.1-A lists places of religious worship at 71 people per 1,000 square feet, among the densest entries in the code, for a room that is full a few hours a week and empty the rest.
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The congregation sizes the system
Outdoor air for each zone is the larger of two figures: 15 cfm per person times the expected occupants, or an area rate times the floor area. In an office the area term governs. In a sanctuary it is not close — at 71 people per 1,000 square feet the people term is about seven times the area term, so the congregation rather than the floor sets the airflow. Where there are pews or other fixed seats, the occupant count comes from the California Building Code.
Demand control ventilation is usually mandatory
Section 120.1(d)3 requires demand control ventilation in any space at 25 or more people per 1,000 square feet whose system has an air economizer, modulating outdoor air control or more than 3,000 cfm of design outdoor air. A worship space almost always crosses the density line, which puts CO2 sensors in the room — at least one per 10,000 square feet — and an acceptance test at the end. Rooms under 150 square feet, or designed for fewer than ten people, are exempt.
Written for a building used in bursts
Three provisions recognise how these buildings are actually used. Places of religious worship carry the table note allowing ventilation to fall to zero while the space is in occupied-standby mode. Mechanical systems serving churches that have seven-day programmable timers are excepted from the usual shut-off control options in Section 120.2(e)1. And the automatic holiday shut-off that time-switched lighting normally needs is not required in churches at all.
The sanctuary is its own lighting category
A religious worship area is defined by its primary function, assembly for worship, and the definition expressly excludes classrooms, offices and other rooms used for something else. The fellowship hall, the children's rooms and the parish office are each calculated in their own category, not under the sanctuary's.
Theatrical lighting used for worship can be left out of the lighting power calculation where it is additional to the general lighting and run from a multi-scene or cross-fade station only authorised operators can reach. Churches are also among the buildings excepted from the minimum daylighting requirement for large enclosed spaces.
Where to go deeper
Sensor accuracy, the 600 ppm control target and the acceptance test are set out under commercial ventilation. A hall that also hosts performances should read the theater requirements, where the stage lighting exclusion is covered in detail.