What is Title 24?

Many Californians have wondered “what is Title 24?” and “why do I need a Title 24 energy report for my project?” Throughout California the Title 24 energy standards address the energy efficiency of new (and altered) homes and commercial buildings. Because energy efficiency reduces energy costs, increases reliability and availability of electricity, improves building occupant comfort, and reduces impacts to the environment, standards are important and necessary for California’s energy future. In 1978 the California legislature enacted the Title 24 energy standards. The standards are contained within Title 24, part 6 of the California Code of Regulations.

Energy Savings and Title 24

The goal of the California Title 24 energy standards is the reduction of energy use. This is a benefit to all. Homeowners save money, Californians have a more secure and healthy economy, the environment is less negatively impacted, and our electrical system can operate in a more stable state. The 2008 Title 24 standards (for residential and nonresidential buildings) are expected to reduce the growth in electricity use by 561 gigawatt-hours per year (GWh/yr) and reduce the growth in gas use by 19 million therms per year (therms/yr). The savings attributable to new low-rise residences are 102.2 GWh/yr of electricity savings and 7.4 million therms. These savings are cumulative resulting in 6 times the annual saving over the 3 years to the next Title 24 standard cycle.

Residential Lighting and Title 24

The Title 24 residential lighting requirements apply only to permanently installed luminaries (light fixtures), not portable lamps that are provided by the occupant. The installed wattage of permanently installed luminaries must be considered only in kitchens. For each room or area, the requirements may be summarized as follows:

High Efficacy Luminaries

According to the Title 24 energy standards a high efficacy luminaries contains only high efficacy lamps or high efficacy LED lighting, and must not contain a socket which allows any low efficacy lighting system to be used. For example, any luminaries containing a medium screw base socket is classified as low efficacy, regardless of the type of lamp installed into that socket. Typically, high efficacy luminaries contain pin-based sockets, like compact fluorescent or linear fluorescent lamp sockets, though other socket types such as screw sockets specifically rated only for high intensity discharge lamps (like metal halide lamps) light emitting diode (LED) luminaries (dedicated LED lighting fixtures that cannot use incandescent or any other type of lighting technology) may also qualify as high efficacy.

Kitchens

Kitchen lighting includes all permanently installed lighting in the kitchen. Lighting in areas adjacent to the kitchen, such as dining and nook areas, are considered kitchen lighting if they are not separately switched from kitchen lighting. At least half the lighting watts installed in a kitchen must be consumed by high efficacy (see definition below) luminaries. For example, if 150 watts of high efficacy lighting is installed, no more than 150 watts of low efficacy (incandescent) lighting can be installed. There are no limits to the total number of watts that can be installed in a residential kitchen.

Detached Garages, Laundry Rooms, and Utility Rooms

All luminaries shall be high efficacy and shall be controlled by a vacancy sensor. Closets that are less than 70 square feet are exempt from this requirement.

 Bathrooms

At least one luminaries must be high efficacy and all other luminaries must be high efficacy or controlled by a vacancy sensor.

All Other Rooms

This applies only to rooms that are not kitchens, bathrooms, garages, laundry rooms or utility rooms. All installed luminaries shall either be high efficacy or shall be controlled by a vacancy sensor or dimmer. Exceptions to this requirement include closets <70 ft2 and lighting in detached storage buildings <1000 ft2 located on a residential site.

Residential Outdoor Lighting

All luminaries mounted to the building or to other buildings on the same lot shall be high efficacy luminaries, or may be low efficacy if the control requirements of section 150.0k(9A) are met. 

Commercial

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 day lighting controls in daylight 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.

Lighting Trade-offs

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 from the CEC Title 24 Residential Compliance Manual)