Infinis is generating a lot of interest this year among its staff, as well as 10% of the UK's renewable energy. Employees are offered up to £6,500 to be as environmentally friendly at home as they are at work. The Northampton-based firm gives workers grants to buy fuel-efficient cars and green technology to use in their home.

A rise of seven places in our rankings this year is tangible reward for the company's efforts.

It's clear that Alan Lovell, the chief executive, puts environmental considerations high on his priority list, earning the company a positive green score of 78% in our staff survey.

Infinis develops renewable power from sources that include gas from UK landfills, which it burns to make electricity for export to the grid. Methane, the main component of landfill gas, is 21 times more damaging to the climate than CO2, and Infinis, the largest provider of this service, reduces the nation's greenhouse gas emissions by the equivalent of more than 9m tons of CO2 a year. It has spent £35m in the past two years on the development of landfill gas power stations, biomass plants and wind farms. The company has also introduced monitoring of its electricity usage and bought fuel-efficient vehicles to cut its own environmental impact.

Infinis doesn't opt for the cheapest rather than the most environmentally friendly solution (81%). Staff fully understand what their carbon footprint is (76%), and are aware of the green implications of the job they do (89%, a result bettered by just three firms). They know that the way they do their job reduces the company's eco impact (77%).

Employees believe Infinis, which places a contractual requirement on suppliers to manage and reduce waste, does a lot for the environment (88%) and that its green commitments are at the heart of how it operates (85%). The offices are not always too warm when the weather is cold (84% — only five firms scored higher on this) and while most staff members travel to work by car, earning Infinis a green score of just 40%, their family and friends think the firm is green (84%).

The company encourages its workforce to take part in its community programme (75%). This year it launched an Energy Challenge, which tied in with National Science Week and involved a donation of a smart electricity meter to local schools. The challenge was to find innovative, unusual or effective ways of reducing energy consumption. All in all, Infinis employees think its green commitment is very serious (90%).