Supermarkets are on the frontline in the fight against climate change. Their sheer size and dominance mean they are major contributors of greenhouse gas emissions, plastics and food waste.
What's more, their future existence depends on getting these issues under control – having resilient, dependable supply chains will be key to their survival as staples in the UK's economy.
Supermarkets face sustainability issues on multiple fronts. Firstly, their operations – powering their shops, refrigerators, delivery vans and depots, packaging their products and handling their waste. And secondly, the products they sell have big environmental impacts, whether it’s carbon emissions from shipping them across the world, or issues such as deforestation and water use in their production.
They also play a key role when it comes to influencing both consumers and suppliers – what they stock, as well as how it’s labelled and priced, can all make a difference. How their businesses compare when it comes to key environmental sustainability issues is crucial but hard to find out.
That’s why we’ve dug deep into their annual reports, crunching the data and asking the difficult questions to find out which are the greenest grocers of them all – and what more needs to be done.
We assessed supermarkets’ sustainability by comparing them on three key measures: their business-wide greenhouse gas (GHG) emissions, plastic use and food waste:
|Rank||Supermarket||Greenhouse gas emissions score (max 25)||Plastics score (max 12)||Food waste score (max 11)||Overall score|
TABLE NOTES Overall supermarket percentage scores are based on a combination of all 10 metrics (see tables below for further info). Scores are weighted: GHG emissions score makes up 50% of the total; plastic score 25%; and food waste score 25%. Note: some of the data used is self-reported and has not been independently verified by Which?.
Lidl and Waitrose jointly top our overall table as the greenest supermarkets. Lidl might be best known for its prices but it seems its ultra-efficient business model that keeps these low also helps make it the greenest of the big UK supermarkets. Its carbon emissions are lower than almost all the others and it has a very ambitious target to reach net zero. It produces smaller amounts of plastic for the volume of items it sells than most rivals and has one of the highest proportions of own-brand plastic that’s recyclable in household collections. However, it's near the bottom of the table for its food waste.
Waitrose did very well on plastic use, as well as achieving relatively high scores on greenhouse gas emissions and food waste. Together, they are both clear leaders of the supermarket pack.
Iceland sits at the bottom in our analysis, performing worst on greenhouse gas emissions by a fair way. This might be due to its focus on frozen food, which requires energy-hungry cold storage. It also uses the most plastic relative to the number of items sold. One positive, however, is that it does relatively well on food waste.
Our groundbreaking research is the first to compare shops on a range of sustainability criteria, including their first full year of mandatory greenhouse gas emissions reports. Most supermarkets publish these figures in their annual reports, but in order to compare them fairly we also worked with the supermarkets to acquire the most accurate and directly comparable data available.
To make it as fair as possible, we used intensity measures for some key data – measuring greenhouse gas emissions per million pounds sterling of revenue, and plastic use per 100,000 grocery packs sold. And similarly, we looked at food waste not as an absolute total, but as a proportion of the food on sale.
We compared greenhouse gas emissions from the supermarkets’ entire operations – including stores, deliveries, warehouses and other services – which they directly control.
Wider supply chain emissions can be more than 90% of the total, so are crucially important, but none of the supermarkets report comprehensively on these yet, so we couldn't include them.
It’s worth noting that these retailers have different business models, which inevitably affect these comparisons – whether it’s online-only Ocado with more delivery-related emissions or Iceland using more energy for its freezers.
Here's how the supermarkets compare when it comes to organisation-wide greenhouse gas emissions:
|Supermarket||Greenhouse gas intensity score (max 20)||Scope 1 and 2 net zero target score (max 3)||Scope 3 emissions reductions score (max 1)||Scope 3 net zero target score (max 1)||Total greenhouse gas emission score (max 25)|
Table note: We compared operational, or Scope 1 and 2, carbon emissions, which are those generated by the companies themselves, mainly from the use of energy and fuel. We scored supermarkets on their emissions intensity, which is the tonnes of CO2 equivalent emissions they generate per £1m of revenue. Not all supermarkets measure wider supply chain, or Scope 3, carbon emissions, so we did not directly compare these. We also awarded points based on the supermarkets’ emissions reduction goals: net zero Scope 1 and 2 target; reducing Scope 3 emissions; and net zero Scope 3 target. a Morrisons operational emissions include manufacturing sites in addition to stores, as it was not possible to separate store-only data. b GHG emissions reported for Ocado Retail are an internal estimate based on a percentage of Ocado Group emissions.
We compared operational emissions, which are referred to in the industry as ‘Scope 1 and 2’. These are the ones that companies can reduce most easily, by using energy more efficiently and switching to low-carbon and renewable fuels.
Aldi, Co-op, Iceland, Lidl, M&S and Tesco all told us they use 100% renewable energy in stores. While commendable in terms of supporting a greener energy market, our research shows some renewable tariffs are greener than others. Therefore, we’ve compared carbon dioxide emissions using the average emissions factor for the national grid, as reported by supermarkets themselves, per million pounds of revenue.
All the supermarkets we surveyed have a net zero target date, meaning that they are aiming for a point at which they will remove the same quantity of greenhouse gases from the atmosphere as they emit.
Iceland’s emissions intensity is almost four times that of the lowest emitters (Aldi and Lidl). That means every pound spent in Iceland results in four times the emissions of a pound spent in the other discounters.
Although supermarkets don’t comprehensively report supply chain emissions (referred to as Scope 3), they do plan to reduce them. Supply chain emissions are harder to control, requiring the co-operation of a global network of producers, manufacturers and distributors.
Here's how the supermarkets compare on plastics:
|Supermarket||Plastic intensity score (max 5)||Plastic recyclability score (max 5)||Plastic reduction / recycling target score (max 1)||100% recyclable / reusable / compostable target score (max 1)||Total plastic score (max 12)|
Table note: The plastic use scores are based on comparative plastic intensity. We’ve calculated this as how many tonnes of plastic are placed on the UK market per 100,000 own-brand and branded grocery items sold, according to industry data. We’ve also scored them for the percentage of own-brand plastic that’s recyclable at kerbside; whether they have targets for the reduction and recyclability of plastic; and target dates for making 100% of all plastic sold recyclable, reusable or compostable. c Iceland was unable to report the percentage of its own-brand plastic that was recyclable, so received no score.
The supermarkets all plan to make their plastic packaging 100% reusable, recyclable or compostable by 2025 at the latest. By weight, 94% of Co-op own-brand plastic is already recyclable at home, with the remainder recyclable in-store. Ocado has further to go: less than 40% of its own-brand plastic is recyclable at kerbside. M&S told us it aimed to make all food packaging recyclable by the end of this year.
Using less plastic is better for the environment than recycling, so we compared how many tonnes of plastic each supermarket puts onto the market annually, per 100,000 items sold. We found that Iceland’s plastic intensity was the worst, while Waitrose does the best. We found buying a basket of 20 items at Iceland could result in 73% more plastic packaging than buying 20 typical items at Waitrose.
Here's how the supermarkets compare on food waste:
|Supermarket||Food waste intensity score (max 10)||2030 food waste reduction commitment score (max 1)||Total food waste score (max 11)|
Table note: These scores are based on comparative food waste intensity. This is measured as how much food waste is generated as a percentage of total food sales. We’ve also given them points for their commitment to reducing food waste by 50% by 2030. d M&S was unable to report its food waste as a percentage of total food sales, so received no score..
We’re pleased to see that no UK supermarket sends food waste to landfill, and they’ve all pledged to cut food waste by 50% by 2030. Tesco and Ocado redistribute the majority of their surplus food for human consumption (eg. to food banks), while the rest send the majority for anaerobic digestion (AD) to be turned into biogas and compost. M&S also told us it has donated 34 million meals to charity since 2015.
We asked supermarkets to report the amount of food waste going to AD as a percentage of their total weight of food sales. Ocado does best, at just 0.04%. Aldi, Co-op, and Lidl’s food waste is considerably higher at around 1% of total food sales. For every kilo of food bought at these stores, around 10g of food is wasted; at Ocado, it’s just 0.4g.
Many of these issues can seem beyond the power of ordinary consumers, but there are important ways we can act.
Your individual circumstances – where you shop, what you buy, how you get there, and what you do with the food once home – all make an impact. Only you will know where you can make the best, and most practical, changes for your household.
There are key choices you can make in the supermarket aisles – here are some of our top tips:
We’ve looked at three of the biggest environmental sustainability issues to create our greenest grocer league tables. But it’s only the start of the story – other issues to consider include water use, deforestation, organic production, sustainable fish, and biodegradable cleaning products, for example. These are mostly further down the supply chain, beyond the scope of the supermarkets’ direct operations, and comparable data can be hard to find.
We want every supermarket to set ambitious greenhouse gas reduction targets, for their own operations as well as the wider supply chain, with clear steps to reach them.
They should also eliminate unnecessary plastic and make their own-brand plastic as widely recyclable as possible – and labelled as such. Plus, we’d like to see a focus on food waste: it’s simply not good enough that Aldi, Co-op and Lidl have 24 times as much food waste proportional to their size as Ocado, for example.
We have investigated the packaging of popular groceries over the past few years. Our latest grocery packaging investigation, conducted in September 2020, looked at 89 best-selling brands like Cadbury and Coca-Cola.
Our analysis found only just over a third had packaging that was fully recyclable in household collections. And almost four in 10 had no labelling to show if it could be recycled. And there were big differences in packaging for very similar products. Some brands use easily recyclable packaging, while others offer almost-identical products with packaging that’s very hard to recycle.
|Weight of recyclable packaging %||Weight of packaging recyclable at bring banks %||Weight of not easily recyclable packaging %||Proportion with recycling labelling|
|Chocolate||70%||0%||30%||1 out of 10|
|Fizzy drinks||100%||0%||0%||10 out of 10|
|Bagged snacks||3%||4%||93%||5 out of 10|
|Yogurts and potted desserts||94%||0%||6%||3 out of 10|
|Sports and energy drinks||94%||0%||6%||5 out of 5|
|Sweet biscuits||83%||0%||17%||2 out of 10|
|Juice drinks and smoothies||95%||2%||3%||9 out of 10|
Almost all of the UK's major supermarket chains have signed up to the UK Plastics Pact, which launched in April 2018.
The pact, led by sustainability experts at WRAP (Waste and Resources Action Programme), aims to tackle plastic waste by bringing together businesses from across the entire plastics value chain, UK governments and NGOs.
More than 120 organisations, including major food and drink brands, manufacturers, retailers and plastic reprocessors, have signed up to hit a series of targets by 2025. These include:
A UK government ban on single-use plastic straws, stirrers and cotton buds came into force in October 2020. And the Government plans to introduce a tax on plastic packaging with less than 30% recycled plastic in April 2022.
But Which? still believes more needs to be done.
Clear recycling labelling would make a big difference. We know 67% of Which? members often or always look for recycling info on grocery packaging before deciding how to dispose of it.
That’s why Which? is calling for recycling labelling to be made compulsory on all UK grocery packaging – branded or otherwise – so that consumers know what can and can’t be recycled, and how.