Diageo Ireland has been accredited with a "smart energy" standard, only the second company in Ireland to do so.
The company's St James's Gate Brewery, which is the home of Guinness, received the IS393 Energy Management standard for its approach to energy use and management.
Diageo claims that in an eight-month period, it cut water usage by 8.5%, reduced thermal energy use by 7.5%, and used almost 5% less electrical energy.
In addition, the brewery's Combined Heat Power (CHP) system has saved more than 80,000 tonnes of CO2 emissions between 2004 and 2006.
The 56-acre brewery has been in place for nearly 250 years, and produces 500 million litres of beer annually.