Non-Residential Lighting and Title 24
Indoor lighting is one of the single largest consumers of energy (kilowatt-hours) in a commercial building, representing about a third of electricity use. The objective of the Title 24 non-residential lighting standards is the effective reduction of this energy use, without compromising the quality of lighting or task work. The Title 24 non-residential lighting standards are the result of the involvement of many representatives of the lighting design and manufacturing community, and of enforcement agencies across the state. A great deal of effort has been devoted to making the lighting requirements practical and realistic.
The primary mechanism for regulating indoor lighting energy under the standards is to limit the allowed lighting power in watts installed in the building. Other mechanisms require basic equipment
efficiency, and require that the lighting is controlled to permit efficient operation.
Mandatory Lighting Controls
The simplest way to improve lighting efficiency is to turn off the lights when they are not in use. All lighting systems must have switching or control capabilities to allow lights to be turned off when they are not needed. In addition, it is desirable to reduce light output and power consumption when full light output is not needed. These mandatory requirements apply to all nonresidential, high-rise residential and hotel/motel buildings for both conditioned and unconditioned interior spaces. A partial list of the Title 24 non-residential mandatory lighting control requirements can be summarized as follows:
- Light switches (or other control) in each room
- Separate controls for general, display, ornamental, and display case lighting
- Occupant sensors in offices 250 ft2 or smaller, multi-purpose rooms less than 1000 ft2, classrooms of any size, and conference rooms of any size
- Partial ON/OFF occupant sensors are required in aisle ways and open areas in warehouses, library book stack aisles, corridors, and stairwells
- Multi-level control (dimming capability) for lighting systems > 0.5 W/ft² in rooms > than 100 ft2.
- Automatic daylighting controls in daylit areas >100 ft2 except when the total installed general lighting is less than 120 watts or the glazing area is less than 24 ft2.
- Demand responsive controls in buildings larger than 10,000 ft2 capable of being automatically reducing lighting power by a minimum of 15% in response to a demand response signal
Detailed descriptions of these and additional mandatory control requirements can be found in the CEC Non-Residential Compliance Manual.
The Title 24 non-residential lighting standards restrict the overall installed lighting power in the building, regardless of the compliance approach. However, there is no general restriction regarding where or how general lighting power is used. This means that installed lighting may be greater in some areas of the building and lower in others, as long as the total does not exceed the allowed lighting power. Trade-offs cannot be made between conditioned and unconditioned space.
There is another type of lighting trade-off available under the Title 24 standards. This is the ability to make trade-offs under the performance approach between the lighting system and the envelope or mechanical systems. Trade-offs can only be made when permit applications are sought for those systems involved. For example, under the performance approach, a building with an envelope or mechanical system that is more efficient than the prescriptive efficiency requirements may be able to meet the standard design energy budget with a bit more lighting power than allowed under the prescriptive approach. When a lighting power allowance is calculated using the performance approach, the allowance is treated exactly the same as an allowance determined using one of the other compliance methods. No trade-offs are allowed between indoor lighting and outdoor lighting or with lighting that is in unconditioned spaces.
(Excerpted form the CEC Title 24 Non-Residential Compliance Manual)