Your daily shop-bought butty might be delicious but, according to a new study rating the carbon footprint of the nation’s favourite sandwiches, buying ready-made is definitely not good for the planet.

Researchers from the University of Manchester have found that prepackaged sarnies containing cheese, prawns or pork – such as bacon, ham or sausages – are bad news for the environment. And the worst is the ‘all-day breakfast’ sandwich featuring egg, bacon and sausage which generates 1,441 grams of carbon dioxide equivalent (CO2 eq.) – roughly the same emissions as driving a car for 12 miles.

Sandwiches made at home are better for the planet, the researchers found, with the humble ham and cheese sarnie proving to be most environmentally-friendly of the nation’s favourites. Specifically a sandwich made from 58g of bread, 8g of ham, 20g of cheese and 13g of mayo.

The study considered the carbon footprint of 40 home-made and pre-packaged sandwiches, and looked at the whole life cycle of sandwiches: from the production of ingredients and packaging, to food waste. The most significant finding was that making your own sandwiches at home can reduce carbon emissions by a half.

Some of the largest contributors to a sandwich’s carbon footprint are: agricultural production, processing ingredients, keeping sandwiches chilled in supermarkets and shops, packaging material and transporting materials. In ready-made sandwiches in particular, researchers recommend avoiding ingredients that have a higher carbon footprint such as lettuce, tomato, cheese and meat.

The worst sandwiches in terms of carbon footprint 1. Ready-made all day breakfast: 1,441 CO2 eq. 2. Ready-made ham and cheese: 1,350 CO2 eq. 3. Ready-made prawn and mayo: 1,255 CO2 eq. 4. Ready-made egg and bacon: 1,182 CO2 eq. 5. Ready-made ham salad: 1,119 CO2 eq.
According to the British Sandwich Association (BSA) more than 11.5 billion sandwiches are consumed each year in the UK alone. Around half of those are made at home with the rest bought in shops, supermarkets and service stations.

That means the UK spends nearly £8 billion a year on them, at an average cost of £2 per snack.

Professor Adisa Azapagic, from University of Manchester’s School of Chemical Engineering and Analytical Sciences, said: “Given that sandwiches are a staple of the British diet as well as their significant market share in the food sector, it is important to understand the contribution from this sector to the emissions of greenhouse gases.”

She said consuming 11.5 billion sandwiches annually in the UK generates, on average, 9.5 million tonnes of CO2 eq. This is equivalent to the annual use of 8.6 million cars.

So next time you consider buying a shop-bought bap, you know what to do.