The Green List puts companies of all sizes and environmental impacts together in one league table, but the tables published here show how each company fared compared to others of similar size and carbon footprint.

The table toppers in each section received their awards at a ceremony held on London’s South Bank.

The top big company with high environmental impact, the construction firm Carillion, is no newcomer to environmental management. It has had an environmental policy for 14 years and assesses the carbon footprints of all the projects it works on. This includes recommending the use of sustainable building materials.

Away from the building sites, Carillion is also trying to change the way it does business. Energy consumption at its Wolverhampton head office was cut by 12% last year and the firm uses renewable energy. It aims to cut carbon emissions to 50% of 2006 levels within two years.

Co-operative Financial Services, the best big and mid-sized company with medium environmental impact, undertook Britain’s largest solar power installation two years ago, installing panels on the sides of its now renamed landmark Co-operative Insurance Solar Tower in Manchester. The firm scores second highest in our survey among its employees for having an ethical investment policy for its pension fund, earning a 71% green score.

The National Magazine Company shows that low environmental impact companies can still achieve big savings. Natmags wins the best big or mid-sized company with low environmental impact award, having increased recycling by 25% and cut energy consumption by 19% in a year.

Among small companies, coffin manufacturer J C Atkinson and Son won the category for high and medium environmental impact businesses as well as winning the overall competition to be named Britain’s Best Green Company.

Loughborough Students’ Union took the honours for small organisations with low environmental impact. The students at Britain’s sportiest university achieved a huge 35% cut in energy consumption and doubled its recycling.

An award for the greenest workforce went to Good Energy. The electricity supplier achieved the top score in no less than 28 of the 52 statements in the employee survey. J C Atkinson and Son won a third award for outright environmental performance, while Saint-Gobain Glass won the training and motivation award.