Title 24 Requirements for Office Buildings in California
Lighting decides most office compliance. Installed power is capped per function area, and offices larger than 250 square feet require occupant sensing — with a zoning rule that catches more designs than the fittings ever do.
The zoning rule that fails open-plan designs
Occupant sensing is required in offices greater than 250 square feet. Where multi-zone sensing is used in an office over that size, the control zones have to be 600 square feet or less, an unoccupied zone must reduce its lighting by at least 80 per cent at the preset time delay, and with every zone unoccupied the controlled lighting must switch off.
A single sensor covering a large open floor therefore fails on zoning even when the sensor works perfectly. It is the most common reason an office lighting scheme does not pass acceptance testing.
Power follows the room schedule
Allowed lighting power comes from Table 140.6-C by space category, and an office building is rarely one category. Open office, private offices, meeting rooms, lobby, corridors and storage each carry their own density, and the permitted total is the sum. A plan that labels rooms by number rather than by use has to be interpreted before it can be calculated.
Corridors and stairwells are in scope too
Both appear on the occupant-sensing list in their own right. They are circulation rather than occupied space and are the element most often left off a controls scope, which then surfaces at test rather than at design.
Mechanical, when the fit-out touches it
Many office fit-outs leave the base building services alone, which keeps them to a lighting submittal. Where they add a supplementary unit for a server or conference room, rework zoning, or relocate ductwork, the mechanical requirements come in — and above 33,000 Btu/hr of design cooling capacity an economizer is required.
Both disciplines are acceptance tested
Lighting controls and mechanical systems are the two disciplines requiring functional testing on site by a certified technician. An office project touching both needs both certifications represented, which in practice often means two people.