Around 35,000 street lights will be switched off – more than half of Cornwall’s entire street lighting – within the next few months. The news comes as the cost of lighting the Duchy at night is set to increase by over £1m a year.

In a bid to save money as well as reduce emissions, 670 lights are already being switched off between the hours of midnight and 5am, though eventually around 35,000 of Cornwall’s 56,000 lights will also be switched off during those hours. All lights that remain switched on will be dimmed.

The council has said the measures will be introduced alongside an ongoing plan to upgrade more than 55,000 street lights with LED fittings by 2025. It was revealed at a council meeting this week that the cost to the local authority of street lighting is increasing by £1.3m a year.

A spokesperson for the council said: “Street lighting is subject to the effects of considerable energy cost inflation. The prices went up by 92% last October – effectively doubling – and have changed little since then. We are doing what we can to mitigate these increases, including introducing the LED bulb replacement programme which in turn enables the night-time switch off. It allows us to dim the lights that stay on, as well as turning lights on later in the evening, and off earlier in the morning.

“These initiatives will deliver savings, although cost inflation and market forces make it challenging to provide accurate predictions.”

Cllr Stephen Rushworth asked at a meeting of the council’s customer services scrutiny committee this week: “Why is street lighting increasing by £1.3m a year when the strategies are to drop lighting and make it dimmer and save money.” The council’s chief operating officer Tracie Langley told him she would forward a report as to why, which will no doubt correspond with the information the council has given us.

Lighting will remain in certain locations throughout the night for safety reasons. Those areas include traffic junctions, subways, pedestrian crossings, parts of town centres, areas with CCTV equipment, and entrances to hospitals and police stations.

The authority has said other councils have not seen an increase in crime or road accidents when adopting similar schemes.

Martyn Alvey, the council’s portfolio holder for climate change, said the street light network made up about a third of the council’s total emissions: “Carbon reduction is a primary driver for taking action to replace street lights and turn them off or dim them when appropriate.

“We are acting to cut carbon emissions, reduce energy use, reduce light pollution to help nature recovery, as well as help offset the increase in energy prices, as we take another step towards reaching our carbon neutral goal.”