Trying to cut your carbon footprint? Lidl and Waitrose are the greenest supermarkets, according to our latest ground-breaking research.
In a brand-new study, we collected hundreds of pieces of supermarket data, both from their published reports and by asking the companies directly. We then analysed them all together to compare the sustainability of the UK's eleven biggest supermarket chains.
Lidl scored highly for its low greenhouse gas (GHG) emissions and targets, while Waitrose did consistently well across all the categories we looked at.
We uncovered who does best for GHG emissions, plastic use, and food waste, as well as who came bottom of our supermarket sustainability rankings.
Sharing top spot in our sustainability rankings, both with a score of 74%, are two quite different supermarkets: no-frills discounter Lidl and high-end grocer Waitrose.
Lidl impressed with its low GHG emissions intensity - how many tonnes of carbon dioxide equivalent it emits per million pounds of revenue - and its aim to become carbon neutral this year. It also scored well on plastics, with a high proportion of its own-brand plastic being easily recyclable, although it did less well when it comes to food waste.
Waitrose scored well across the board, with reasonable GHG and food waste scores, and it uses the least plastic compared to the number of items sold, measured as tonnes of plastic placed onto the market per million packs of groceries sold.
Asda and Sainsbury's tied in a respectable third place, three percentage point behind the leaders.
The sheer size and dominance of the big supermarkets means they have a big impact on the environment, through powering their shops and refrigerators, operating delivery vans and depots, packaging their products and handling their waste.
We know that the biggest issues for shoppers are the use of plastic packaging and the impact of food waste, while experts generally agree that greenhouse gas emissions pose the greatest global environmental threat. We looked at all three issues to see exactly how the supermarkets compare. We weighted GHG emissions as 50% of a company's total score. Food waste and plastic usage make up 25% each of the total.
Iceland finished at the bottom of our rankings, performing worst on greenhouse gas emissions by some margin. This may be due to the high proportion of frozen food it sells; it takes a lot of energy to keep products cold throughout the supply chain, from manufacturing to warehouses, stores, and delivery vehicles. It does, however, buy 100 per cent renewable electricity for its UK sites.
Iceland also uses the most plastic relative to the number of items sold, and received a relatively average score for food waste, resulting in a total score of just 29% overall.
While no supermarket excelled in every metric we considered, there were clear front runners in individual categories, suggesting that all supermarkets have room for improvement.
Aldi and Lidl achieved the lowest GHG emissions intensity, but Lidl topped our table due to its ambitious target to reach net zero for its operational emissions in 2022. Its emissions are 73% lower than Iceland's, relative to sales revenue.
The Co-op topped our plastic rankings, with outstanding levels of recyclability. Waitrose recorded the lowest plastic intensity (ie. how much it uses compared to the number of items sold), putting it second overall on plastic. Lidl follows in a very respectable third place.
Ocado came top of the food waste table, with the best food waste intensity by some way. In contrast, the Co-op, Aldi and Lidl waste more than twenty times as much food as Ocado, proportional to their food sales.
While supermarket businesses are responsible for their own emissions, plastic and food waste, the products they sell also have big environmental impacts, whether it's carbon emissions from shipping them across the world or issues such as deforestation, pollution, and water use in their farming and production.
Unfortunately, the supermarkets don't yet report comprehensively on all of these measures for the products they stock, so we couldn't compare them on these issues.
However, individuals can reduce their environmental impact by choosing more sustainable products, no matter which supermarket they are shopping at.
Customers can make a real difference with how they shop and what products they choose in the supermarket aisles. Simple steps include: