The team at Atkins helped the multidisciplinary firm retain its Carbon Trust Standard last week thanks to low-carbon initiatives such as reducing energy use in offices.
"We have reduced carbon emissions in a number of ways, for instance by encouraging employees to choose greener company cars," said a representative.
"The average carbon emissions of Atkins’ 1500-strong UK company-car fleet reduced to 136g/km last year against 148g/km the year before."
Atkins also launched a Raising Awareness: Cutting Energy campaign to target reductions in office energy use and has spent £2m on software to measure emissions.
To achieve the Carbon Trust Standard, organisations must measure their carbon footprint, prove they use good carbon management practices, and cut emissions.
The Carbon Trust Standard, valid for two years, was first awarded to the company in 2009 and Atkins has cut 500 tonnes of carbon dioxide in the last couple of years.
UK managing director David Tonkin said:
"The ability to mitigate carbon emissions is very much part of the day-to-day work for our designers and engineers.
"We are tasked with finding innovative ways to cut carbon in our clients’ projects so it is right that we show leadership in our own operations."
Darran Messem, managing director of certification at the Carbon Trust, said:
"There are operational efficiencies and reputational gains to be earned from tackling emissions voluntarily."