Tesco is the most environmentally friendly supermarket in the country. The firm, which wins our award for being the best big company for corporate environmental strategy, has invested £115m in energy-saving technology for its stores in the past two years and is working hard to create the zero carbon supermarket of the future.

Survey results show that employees believe Tesco's environmental commitments are very serious, with a 78% green score. They agree the firm is getting better at protecting the environment (81%) and say that investment in environmental initiatives is money well spent (85%).

The firm's flagship low-carbon supermarket in Cheetham Hill, Manchester, has exceeded its proposed CO2 reduction targets of 50% by a further 20 percentage points.

"The Cheetham store is part of the evolution of technologies and ideas that we want to move on to future stores," says programme manager Jake Ronay. "We want to raise the bar, but I think a 70% reduction since 2006 is a fantastic achievement."

A closer analysis shows that a 31% reduction has been achieved through energy efficiency, 20% by using natural refrigeration and another 20% through renewable energy.

Onsite wind turbines power the sign at the front of the building and a combined cooling, heating and power plant provides 25% of the store's electrical needs, as well as 50% of its refrigeration. The plant is run on vegetable oil, reducing carbon emissions by 78%.

The supermarket also harvests rainwater from the roof, which supplies the store with 50% of its toilet flushing requirements. Built with wood from sustainable forests, a glass front and roof lights allow the building to make maximum use of natural light. Store lights automatically dim or switch off depending on the availability of sunlight, ensuring an 8% energy saving.

Ronay says: "You can't wave a magic wand, but you can look at efficient use of energy, and equipment in the store, especially refrigeration, as well as the way things are run."

Other innovations within the store include natural ventilation and a metering system to monitor energy use. Tesco has also increased its use of recyclable materials in signs and fixtures and, according to Ronay, this and many of the other features within the new store are fast becoming national standards for the firm.

"It seems like such a small thing, but when you see the amount of signs in a store and then look at the number of stores, you realise you've made a huge impact," he says.

According to Tesco's head of environment, Bukky Adegbeyeni, large emission reductions have been achieved across the board.

"We're constrained by the existing structures we are in. You are not going to pull down a building, but you can make improvements in lighting and refrigeration," she says. "In terms of existing stores, we're also looking at making certain designs and equipment standard, such as appliances like power perfectors that rationalise energy use and have so far helped us to save 15% to 20%."

Tesco has also introduced a range of new products to be more environmentally friendly. Its Greener Living range is worth more than £100m a year. In October, the chain reduced the cost of energy-saving lightbulbs from £1 to 40p and as a result, sold 3.5m in a month.

According to Tesco's community and government director, David North, a supermarket has a responsibility to educate and encourage the consumer. "When we reduced the price of energy-saving lightbulbs it revealed a latent pent-up demand," he says. "Customers want to be green, but they are looking at businesses to help set an example." Nevertheless, despite staff in the Cheetham Hill branch being turned into "eco fans", as one employee put it, at 58th nationally, survey scores suggest workforce engagement needs to be addressed. With energy champions, recycling and energy-saving training, Tesco has a strong foundation on which to enthuse and empower its staff to bring the environment to the forefront.