One-watt technology uses digital LED driver modules. This eliminates the need for load resistors and switching elements in the signal light units which until now have consumed most of the energy. Compared with the 60 watts sometimes consumed by incandescent bulbs, the electricity required by individual traffic light signals can be slashed to just one or two watts. State-of-the-art LEDs with extremely low power consumption still retain full light intensity. In addition to power costs, the 1-watt light units also reduce service costs. Optical monitors continuously check the state of the LEDs. It is conceivable that in the future it may be possible to predict when units will fail, thus enabling preventative maintenance of signal light units. Siemens is the first ever manufacturer worldwide to monitor not only voltage and current, but also the luminosity of the LED signal light units. With this multi-layered monitoring concept, the 1-watt traffic light achieves the highest level of safety in road traffic (SIL 3).
With 1-watt technology, a large city like Berlin can avoid some additional 2,000 tons of carbon emissions and save 500,000 euros in energy costs every year. If these efficient traffic lights are not used, a city like Berlin would have to plant around 2,000 deciduous trees every year to compensate for the otherwise resulting carbon emissions. Since the typical lifetime of a traffic light is more than ten years, a forest of 20,000 broadleaf trees would have to be planted to offset the harmful emissions of an intersection with conventional lights. In cities that still use large numbers of filament light bulbs instead of LEDs, the potential savings for energy costs and emissions are significantly higher, with newly-installed, 1-watt technology traffic signals at a typical intersection paying for themselves in less than five years.