Upgrading a lighting system can reduce energy consumption in two ways. Since Energy = Power x Time, we can either reduce the lighting system's input wattage (W or kWh) or reduce its hours of operation. As the kW and the kWh are the basic products for which an electric utility charges, significant operating cost savings can result that can pay for the investment and then reduce a desirable return on that investment.

Common Upgrade Strategies:

Upgrade with reduction in light levels

In some applications, ambient light levels can be reduced, particularly in spaces where ambient light is needed only for the task of orientation, in spaces where planned lighting maintenance is resulting in a light level higher than originally planned for, and in spaces where IES light level recommendations have been revised (that is, reduced).

Approaches include dimming, lamp/ballast removal, specular reflectors, reduced-output (lower-wattage lamps) and current limiters.

Increase light levels

This entails increasing light levels via planned lighting maintenance, specular reflectors, higher room surface reflectances or higher-output lamps and other approaches; after light levels are increased, we are then afforded the options to then reduce light level and save energy as shown under "upgrade with reduction in light levels."

Maintain light levels

In these spaces, we need to maintain current light levels but can do so by retrofitting with lighting equipment, such as more-efficient lamps and ballasts, to provide comparable light output at a reduced wattage.

Focus light levels

In some applications, the overhead ambient lighting system is doing most of the work in the space, providing illumination for both ambient and task lighting. In many of these applications, by providing portable, adjustable task fixtures at the task locations, we can upgrade to reduce light levels in the ambient system, since its primary function will be re-tasked for orientation only. An example of this approach is an indirect lighting scheme for ambient illumination, with task fixtures.

Reduce hours of use

Controls such as energy management systems, occupancy sensors and daylight-dimming ballasts can be installed to control the hours the lighting system is used, eliminating waste and reducing energy usage.  Here are some useful guidelines to remember when attempting a lighting upgrade:

• The lighting system must serve the design goals of the space; no upgrade should compromise the system's performance in meeting these goals. The upgrade should begin with the question, "What is the spaced used for and how does the lighting support that?"

• There is no magic to new energy-efficient lighting systems; since all lighting equipment operates according to the laws of physics, there are always tradeoffs

• All lighting components must be compatible to operate properly

• All OSHA safety requirements should be met when any work is done on the lighting system

• Ensure that all retrofits are permanent and understood by the maintenance personnel in a written and communicated lighting policy, so that old components are not reintroduced back into the lighting system later (such as when a screw-in compact fluorescent lamp fails and is then replaced with an incandescent lamp)

• Planned lighting maintenance can be an effective means of getting the best results from the lighting system and can help create energy management opportunities

• Be sure to include provisions for legal compliance in disposing of any lighting waste (see Lighting Waste Disposal)