The amber glow of the New York City streetlight is going away. In an energy-saving effort, the city plans to replace all of its 250,000 streetlights with brighter, whiter, energy-saving, light-emitting diode fixtures in one of the nation’s largest retrofitting projects, Mayor Michael R. Bloomberg and the transportation commissioner, Janette Sadik-Khan, said in a news conference on Thursday.

The phasing out is part of the administration’s long-term plan to reduce its greenhouse gas emissions by 30 percent by 2017. Mayor Bloomberg described the switch as a “large and necessary feat” that will save taxpayers money and move the city closer to its sustainability goals. The project is also part of the Transportation Department’s plan for more environment-friendly operations, Ms. Sadik-Khan said.

The news conference was on Eastern Parkway in Brooklyn, where lights have already been replaced, expecting to save more than $70,000 and nearly 248,000 kilowatt-hours a year in energy. Unlike standard lights, which last six years, LED bulbs can burn for 20 years before they need to be replaced, the administration said, and the project is expected to save $14 million a year in energy and maintenance costs.