An article sharing (qouted from www.ledsmagazine.com) :

Cleantech reports lighting controls energy savings

24 May 2010

Research reveals that lighting control schemes can reduce commercial building energy consumption 35% – 55 %, and technologies such as LED lighting could add to the savings.
Lighting comprises as much as 38% of the electricity expense in a commercial building according to a new Cleantech Approach (CTA) research report, but lighting control technology can greatly reduce that energy usage. The "Lighting Controls: Savings, Solutions, Payback, and Vendor Profiles" report projects 35% - 55% energy savings that delivers a payback on the investment in new lighting in 2.7 to 10.7 years.

CTA recommends that companies first adopt a lighting control system when trying to cut energy usage. The company points out that control systems carry little of the technology risk associated with new lighting technologies such as LED-based solid-state lighting (SSL). Moreover CTA expects a control system installed today to be compatible with new SSL technology in the future.

The projected energy savings in the report are due purely to the ability to dim or extinguish lights automatically when they aren't needed. The adoption of a technology such as SSL could further reduce consumption.

The CTA report calculates the investment payback periods based on a range of costs for a lighting upgrade combined their estimates for the energy savings potential. In the worst case scenario, a project would cost $2.50 per square foot and only save 35% in energy expenses resulting in a 10.7-year payback. In a best case scenario, a project would cost $1.00 per square foot and save 55% in energy expenses resulting in a 2.7-year payback.

The potential flaw in the recommendation that companies install lighting controls separately from SSL is that many of the most advanced control schemes are SSL centric (see related stories at right). Moreover, many legacy lights can't be dimmed or turned off-and-on instantaneously.