Royal Mail has announced its first delivery office to have an all-electric fleet of collection and delivery vehicles.
Bristol East Central Delivery Office's 23 diesel vehicles have been replaced by fully-electric ones.
Royal Mail said Bristol was selected because of its plans to introduce a Clean Air Zone (CAZ) later this year.
Chief executive Simon Thompson described the move as a "really positive step".
Six electric charging posts have also been installed on the site, with electricity for powering the office and charging the vehicles coming from renewable sources.
Mr Thompson said the move would allow them to assess the impact of the changes on customers and staff, and consider changes to other delivery offices.
"It's clear to me that customers increasingly want less environmentally impacting deliveries," he said.
"We are delighted to transform Bristol East Central into the very first Royal Mail 'all-electric' delivery office."
The electric vans have a bigger load space than the vehicles they have replaced, giving them additional capacity to deal with growing parcel volumes, and have lower maintenance requirements.
'Reducing emissions'
Bristol mayor Marvin Rees said it was "fantastic news".
"Their 23 electric vehicles will join Bristol's 99 bio-gas buses already on our streets in reducing emissions and improving air quality.
"We want to support people and businesses in transitioning our fleet to cleaner and more efficient vehicles," he added.
Rob Wotherspoon of the Communication Workers Union said: "This is not just about the fight against climate change but about the air that our communities breathe."