The GPCs in Manchester and London, which print the Guardian and the Observer, achieved 9% fall in emissions in the 12 months ending March 2012. A 16% reduction in water usage was partly down to the Manchester GPC, which ran a project to reduce ink usage.

The figures, showing the gains made by efforts to improve sustainability and reduce environmental impact at the GPCs over the 12 months to March 2012, were published in the Guardian this month.

Manchester operations manager GPC Phil Aitken said that the entire staff had been involved in the drive. "As well as improving the amount of ink and water we use, the project is continuously improving staff involvement," he added.

The project helped reduce the overall damp setting by 14% on all inks except cyan. The ink motor speed across the press was also reduced by 23% and efforts were made to make sure ink density checks stayed within specifications set by the GPCs.

Aitken said that these improvements and increased focus of his staff had resulted in an 11% reduction in black ink usage, an 8% reduction in colour ink used and a 6% reduction in water used in the printing process.

Minimum ink water usage has also resulted in reduced web breaks and reducing the need for re-webbing, which Aitken called a "sworn enemy" of the Manchester GPC’s key performance indicator measures.  

"Using less water in the ink has also resulted in sharper images and improved halftones, as well as reduced show-through and ink fly," Aitken said.

The GPCs have also installed smart meters, which give real time information on energy consumption and allow users to manage their energy use and reduce emissions.

Also, by controlling the recirculation of air in the print centres the GPCs have reduced the need for cooling down and reheating air in order to keep a consistent ambient temperature.

Water usage was also reduced by installing sensors in the urinals in the Manchester GPC.

Polestar, the contract printer that prints Guardian magazines has also reduced its carbon emissions by 7%, the figures reveal.