Control modifications can result in substantial cost and energy savings. In
many cases, a building's light switching system was designed so that the central
panel board is the only means of controlling large blocks of lighting. This
arrangement presents no problem during the day, when the space is filled with
workers. However, if just one or two workers stay after hours, all the luminaires
in the space may have to be on, because there is no way to energize only the
three or four that are needed. Localized controls, such as those near doorways
that control small groups of luminaires, can be very effective. Although this kind
of switching modification may be somewhat expensive, in many cases the
payback the amount of time required for savings to equal installation cost is very short.
Other control modifications also are possible. For example, by adding dimming controls to a uniform lighting system, you can almost achieve the same benefits provided by a nonuniform system. This is especially true in the case of incandescent lighting, where dimming systems can be added easily at low cost.
In some situations photocell switching also can be useful. In the case of spaces that receive a lot of daylighting, for example, a photocell can be used to automatically turn off certain luminaires when daylighting illumination reaches a certain level.
