New LED street lights will be shining in York this winter - to cut crime, save hard-pressed charge payers money, and improve views of the night sky.
But they may not always operate at full power because they will be turned down in off-peak periods by council bosses - who say no one will be able to tell the difference.
More than 1,500 lamps will be replaced in seven months to provide clearer "white light" by January in Rawcliffe, Clifton, Huntington, New Earswick, Copmanthorpe, Bishopthorpe and Micklegate.
The areas currently have the highest number of the sodium lights, introduced in the 1980s because the low wattage was cheap - but many found the orange glow depressing.
Police monitoring CCTV cameras also dislike sodium - because it mixes up colours in the dark and makes it harder for witnesses to provide accurate descriptions.
The new LEDS will be reduced by 50 to 60 per cent on streets between midnight and 6am when there is less traffic.
York Council has already experimented with the first LED lights, installed in January on Hamilton Way, Collingwood Avenue, Stewart Road and Amberley Street in Holgate.
They say when the lights were reduced by up to 60 per cent no one noticed.
Cllr David Levene, Cabinet Member for Transport, said: “LED lighting is cheaper, better for the environment, and gives a superior quality of illumination which will help residents feel safer.”
York Police Commander Supt Phil Cain said: “The benefits of the new lighting with regards to improved CCTV images is something that will aid criminal investigations in the city.”
The new street lights cost £200 each, but are expected to save £20 a year - or £30,000 in total.
Reduced maintenance costs and carbon emissions will also mean a £1,200 annual saving.
Cllr Dave Merrett, Cabinet Member for Environmental Services, said: “LED lights reduce light pollution, increase the number of stars visible at night and reduce the effects of unnatural lighting .
"They also halve the amount of energy usage per light by 50 per cent while maintaining current lighting level standards, and they save money."
The York Environment Forum, said: “This is a positive move towards reducing the city’s carbon emissions and it makes sound economic sense."