By installing screw-in replacement LEDison® bulbs from Mule Lighting, Inc, a chain of malls throughout the U.S. has boosted energy efficiency. Working with Sempra Energy Solutions (Houston, TX), a large corporation with over 120 malls came up with a plan to replace 11 W incandescent lamps with 1 W, grouped LED lamps. Michael Lassle, who is responsible for national lighting projects at Sempra, facilitated the project, working with the mall owners and Mule Lighting.

Before converting to LED (light emitting diode) bulbs from Mule, the shopping malls had been using decorative incandescent lighting mounted in the mullions between 4 x 4 ft sections of skylights. Each mall used 3,500-4,500 11 W incandescent bulbs that were lit for approximately 4,000 hours a year -- the average lifespan of a typical incandescent lamp.

Bulb replacement was inconvenient and expensive, in addition to being potentially dangerous. Maintenance time was limited to the hours during which the mall was closed, with no foot traffic. Because skylights are located 30-50 ft in the air, setup and safety precautions required considerable time and cost, and the process was often delayed, leaving unattractive burned-out bulbs in place.

In an effort to provide a cost- and energy-efficient way of lighting these panels -- while decreasing associated maintenance costs -- Lassle approached Mule Lighting, Inc (Providence, RI). Mule designed the LEDison bulb, a simple screw-in replacement for efficient retrofitting, which met the owners' cost, lifecycle, and aesthetic criteria.

The malls were retrofitted during the second and third quarters of 2001. While each lamp cost about $25, estimated energy conservation, operation, and maintenance cost savings will pay for the retrofit at least twice during the life of the LEDs. These savings will grow as energy costs continue to increase, as they have since installation. But while energy savings promise to be substantial, more significant cost savings will accrue from the reduction in required maintenance. The LEDison lamps have an expected life of 10 years without burning out or significantly degrading in light output. This equals 44,000 hours of useful life, more than 10 times the life of incandescent bulbs. This long life also limits the unappealing sight of burned-out bulbs.

"The mall owners achieved considerable cost savings, without sacrificing the quality of any aspect of their end product," says Lassle.