A new conversion scheme will shed light on saving money in Bognor Regis and Chichester.
West Sussex County Council is to use a £26.5m loan over 25 years to install 64,000 LED lamps in its street lights.
The change is expected to produce savings in electricity and maintenance costs of £90.1m during that period.
As part of the scheme, a remote monitoring system will be introduced to control the lights and monitor and identify faults.
This will help to cut costs because of the requirement for fewer site visits and less need for temporary traffic lights and traffic management during maintenance – to reduce delays for road users.
Cllr Roger Elkins, the council’s cabinet member for highways and infrastructure, said: “This is a ‘win win’ for residents and the environment, with reduced electricity and maintenance costs and a 17 per cent decrease in the council’s total carbon emissions.
“The decision to roll-out the scheme, which is subject to the council’s usual call-in period, comes soon after we launched our online climate change campaign.
“It shows our clear commitment to the West Sussex climage pledge and the practical, cost-effective measures we are taking to cut carbon emissions.
“The LED lamps are also designed to have a cleaner ‘cut-off’ of light, so they are efficient at directing light where it’s needed, which also supports a darker sky initiative.
A council spokesman said LED technology had improved in recent years. These units can generate the same amount of light as traditional lanterns but using a lot less energy.
They also have a much longer lifespan. Traditional lighting needs lamp changes every four years.
LED lights will last for about 100,000 hours – equal to some 20 years in the county’s existing areas with lighting for part of the night.
There are already about 2,000 LED lamps in use in the county. Most of the lighting in the South Downs National Park has been converted to them to help to protect natural views of the sky.
The county council’s climate change campaign and the West Sussex climate pledge asks everyone in the county to commit to make small changes.
These include making low carbon journeys, saving water and energy and passing on plastic.
People can find out more about the pledge at: westsussex.gov.uk