Some US cities are looking for a change from the popular sodium-vapor lights in their night sky schemes. For example, Chicago recently announced that it is replacing 16,300 of the old sodium-vapor lights with ceramic metal halide lights. That number may sond like a lot, but it is only a relatively small step forward as the city will still have nearly 10 times that amount of the old luminaries. Chicago is also converting 1000 stop lights (another small proportion) to LEDs. Planners say they will save US$40-70 in electricity per light, and the ceramic metal halide versions will last about 50% longer than the old models. Between the new streetlights and stoplights, the city expects to save $1.8M/per hear and cut CO2-related emissions by 15,000 metric tons. The actual transition is taking place now because of the availability of a $13.8M DOE grant. Lower maintenance costs are also expected. For more information, please visit: www.cityofchicago.org
