Workers have been urged to help tackle climate change by taking simple measures such as switching off computers and lights, reducing waste and walking or cycling to the office.
The TUC called on people to "think green" in the workplace to cut energy use and do more to protect the environment.
The union organisation said workers leaving the office should make sure electrical equipment such as computers and lights were turned off.
As well as recycling, staff could re-use envelopes and print on two sides of paper, turn the heating down, take the stairs instead of the lift and think of greener ways of travelling, it was suggested.
TUC General Secretary Brendan Barber, said: "More and more people are recycling and reducing energy use and waste at home. But for many people work is still a green-free zone, despite being the biggest polluter and power user in the UK.
"There are simple steps people can take to make their workplace greener but to make a real difference it's better to get everybody on board.
"It may seem daunting at first, but if employers, employees and unions get together, problems can be solved and good practice can be spread across the whole organisation."
UK workplaces generate over 66 million tonnes of carbon emissions ever year yet businesses waste 30% of the energy they buy, the TUC said.
