HK scientists develop novel dimming technology for lighting systems

City University of Hong Kong Monday announced its newly developed dimmable lighting technology that can help reduce electricity consumption and protect the environment.

Professor Ron Hui of the university's Department of Electronic Engineering said that the technology has been successfully applied in a number of outdoor lighting systems in Chinese mainland. Field trials have shown that it has the capability of reducing energy consumption up to 30 percent in lighting system.

Reduced electricity consumption leads to reduced carbon dioxide emission, which, in turn, helps relieve global warming, he said.

Hui explained that in electric lighting systems for discharge lamps such as fluorescent lamps and high-intensity-discharge lamps, either electromagnetic ballasts or electronic ballasts would be used to control and limit the current in the lamp.

An electromagnetic ballast has a typical lifetime of 15-20 years and is recyclable and is therefore environmentally friendly. For an electronic ballast, it consumes about 10 to 15 percent less electricity. However, it leads to an environmental problem -- accumulation of toxic electronic waste, Hui told.

The university has developed a central dimming technology that can turn non-dimmable electromagnetic ballasts into dimmable ones, with dimming capability allowing users to use lighting energy when and where it is necessary and to the appropriate lighting level.

The patent-pending central dimming technology can on the one hand save energy, and on the other hand do less harm to the environment during the process of generating electricity. It has been successfully applied to both indoor and outdoor lighting systems.

The novel central dimming control system has been tested in Chinese Mainland since September 2004, registering an average saving of 30 percent of electricity. It is now being installed in a mainland city for controlling about 7,000 street lamps.

According to Hui, if the novel technology is widely applied, one percent of global electrical energy consumption can be reduced annually.