Red Bus will cut its carbon footprint by swapping three diesel buses for electric alternatives on a route between central Christchurch and the airport next year.

Electric buses will carry people on a route between central Christchurch and the airport from next year, a move that will help improve the city's public transport environmental footprint.

Red Bus will swap three diesel buses for electric alternatives on its number 29 service, which carries more than 200,000 passengers every year.

Chief executive Paul McNoe said the reduction in exhaust emissions will cut the fleet's annual carbon footprint by 5 per cent, as well as reducing noise inside and outside the buses.

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Running off batteries, the buses – which will be delivered in March – should require charging only once a day.

"We are expecting immediate environmental and health benefits from these battery electric powered buses," McNoe said.

The company is investigating the potential to expand its electric fleet and will test the new buses on other routes, including Christchurch's hill suburbs.