9.6.3 Install fixtures or combinations of fixtures that provide efficient lighting for all modes of space usage
In many cases, the lighting of a space is designed for one type of activity, and it is inefficient for other usage. For example, nightclubs use incandescent lighting operated by dimmers because the low intensity and warm color of incandescent lighting creates the desired mood. While, this is appropriate during evening business hours, the nightclub needs lighting at much higher intensity for many hours during the day, for activities such as cleaning, rehearsals, and serving the lunch trade. The incandescent lighting is inefficient for such activities.
The most efficient way to provide lighting for such facilities is to install the types of fixtures, or a combination of fixture types, that can accommodate each mode of space usage as efficiently as possible. How well this pays off depends on the total number of hours each year that lighting is needed for each function.
Common Opportunities
Consider all the times that lighting is required in each space, and provide appropriate lighting for each requirement. The following are common situations where different modes of lighting are needed for efficiency.
Spaces that Need Incandescent Lighting for Appearance
Facilities such as restaurants, nightclubs, theaters, and retail stores commonly use incandescent lighting for esthetic reasons during hours when they are open to the public. However, such facilities commonly operate for many hours when esthetics are not a factor. For example, cleaning and restocking require illumination that is bright and widespread, rather than subtle. Consider installing more efficient fixtures to provide illumination for these functions. Fluorescent and HID lighting is about four times as efficient as incandescent lighting, and the lamps last about ten times longer.
Incandescent fixtures often distribute light inefficiently. Downlights, commonly installed without regard to the location of activities, are the most common example. For times when incandescent lighting is needed, try to install incandescent fixtures that have efficient light distribution.
Spaces with HID Lighting
HID lighting tends to be left on in empty spaces because it cannot be restarted quickly. To eliminate this problem, install additional fluorescent fixtures for emergency lighting, transit, and activities that occur outside normal occupancy hours. An alternative is replacing all the existing HID lighting with fluorescent lighting, as recommended by Measure 9.3.3. Emergency Lighting
It is common practice to provide emergency lighting with some of the conventional fixtures. Often, the fixtures are much too powerful for emergency lighting, even though only a fraction of them are used. For example, the 4-tube fluorescent fixtures commonly used in office space each consume about 200 watts. This is vastly more power than needed for emergency egress.
Another disadvantage of this practice is that the lamps in the emergency fixtures burn out more often than the lamps in the other fixtures. This upsets the schedule for group relamping, if this practice is followed.
There are a number of economical solutions. The easiest, most efficient, and cheapest may be to install specialized emergency fixtures in locations that are appropriate for emergency egress. Instead of expending 200 watts per fixture, as in the previous example, each emergency fixture might have a power consumption of about 20 watts. Another improvement is to rewire some of the primary fixtures so that only a reduced number of lamps operate during unoccupied hours (see Measure 9.6.4 for this). However, this solution still burns out one set of lamps at a different rate than the others.
Transit Lighting
The worst situation is turning on all the lights in a space only to pass through it. You can keep this from happening with the circuiting and control methods recommended by Measure 9.6.4. If the lights in the space need to be turned on for long durations to allow transit, install appropriate fixtures for this purpose.
Maintenance Lighting
Industrial facilities typically have equipment that requires frequent maintenance, inspection, and cleaning outside of normal production hours. It may be practical to install specialized lighting for these functions, avoiding the need to turn on the lights in the entire plant.
Control to Prevent Duplication of Lighting Merely installing a variety of fixtures does not make the lighting efficient. In fact, it may make the lighting even less efficient, and also annoying. Figure 1 illustrates this. It is a big challenge to make sure that only the lighting needed for each mode of space usage is turned on. For example, if a nightclub has fluorescent lighting for cleaning, make sure that the incandescent lights are turned off when the fluorescent lights are turned on. Otherwise, the money spent on the extra fixtures