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) luminaires. 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.
According to the Title 24 energy standards a high efficacy luminaire 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 luminaire containing a medium screw base socket is classified as low efficacy, regardless of the type of lamp installed into that socket. Typically, high efficacy luminaires 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) luminaires (dedicated LED lighting fixtures that cannot use incandescent or any other type of lighting technology) may also qualify as high efficacy.