Staff toolkit | Carbon Detectives

How does it work?

Schools are very aware of the importance of promoting healthy lifestyles including the provision of healthy food and drink. Schools should also consider how packed lunches, school meals, snacks and drinks are contributing to their carbon footprint. The environmental impact of different foods depends on a number of factors including:

The farming methods used to produce the raw food items. Fertilizer and pesticides are both made from an oil base, producing CO₂ as they are made.
The amount of processing needed to produce a final food product. Processing uses energy which produces CO₂.
The distance travelled by a food item (food miles) to get it to our plates. Transport produces CO₂.
The distances travelled by all the ingredients found in a processed food item.

The Carbon Detectives’ Kit focuses on how much food is processed. Processing food has the most significant impact because of the energy required. The more processed or packaged food bought, such as tinned fruit or drink, the higher the carbon footprint will be. For example, a glass of water does not result in any CO₂ being produced whereas a can of fizzy drink results in 0.41kg of CO₂. Bottled carbonated water is not much better.

Buying organic and/or locally produced food can also make a difference. But remember that buying a locally processed food product is not always better because of the energy and machinery used to process the product. It is harder to be certain about the impact of organic food. Not all organic food has a lower carbon footprint, although organic milk and eggs certainly have a lower carbon footprint than their non-organic counterparts. Of course, organic food that has travelled a long distance produces a lot of CO₂. For these reasons the calculator does not differentiate local or organic food.

What data is needed?

Food and drink data can be complex. The calculator simplifies this by using standard food categories. To calculate CO₂ emissions the Carbon Detectives Team will need to collect data about school meals. Individual pupils and staff will need to record data about their packed lunches and snacks.

School meals. The Carbon Detectives Team needs to find out the number of portions served by the school over a set period, for example five days. Then they need to enter the total number of portions consumed in each of the categories in the calculator.
Packed lunches and snacks. This is a similar process to school meals but the task is completed by individuals for a single day.

For packed lunches and snacks, the more pupils and teachers that enter data the better. Pupils can even enter data every day if they are able to, as the calculator will work out the average based on all the entries.

The entered data is then multiplied by the CO₂ emissions per portion and totalled to give the final result. The emissions, called conversion factors, include the energy used to process, package and transport the food. For example, tinned vegetables produce 0.12 kg CO₂per portion compared to 0.05 kg CO₂ per portion for fresh vegetables.

Food facts and figures

To get 1kg of UK grown unprocessed potatoes to our plate 170g of CO₂ is produced. To process the 1kg of potatoes into chips 265g of CO₂ is produced.
To produce 1 kg of tomato ketchup produces 1.35kg of CO₂, more than the tomato ketchup itself weighs.
Rearing animals to produce meat results in high CO₂ emissions due to the amount of energy used to produce and transport animal feeds.
Food miles measure the distance food travels from field to plate. Agriculture and food now account for nearly 30 per cent of goods transported on our roads. This travel adds substantially to the CO₂ emissions that are contributing to climate change, which is why food miles matter. A new report by the Department for the Environment, Food and Rural Affairs (Defra) says that food miles rose by 15 per cent between 1992 and 2002.
95 per cent of the fruit and half of the vegetables in the UK are imported. The amount of food being flown into the UK doubled in the 1990s and is predicted to rise each year. To take one example, strawberries are flown in from warmer climates to satisfy our desire for permanent dietary summertime, and air freight has a far bigger impact on the environment than sea or road travel.

What individual pupils can do

Eat more fresh food and produce. The less processed a food item is the fewer CO₂ emissions are likely to have been created.
Buy local food. Don’t travel a long way to supermarkets to buy food that can bought within walking distance.
Eat less meat and replace it with nuts, beans and pulses which are a more energy-efficient way of providing edible protein.
Try to avoid or limit the amount of convenience, highly processed food they bring for their lunch.
Drink more water and consume fewer fizzy drinks.

What a school community can do

Talk with school catering managers and support initiatives to:

Reduce the amount of highly processed food served by the school canteen. The more processing procedures a food product has been through the greater the CO₂ emissions released in production.
Reduce the amount of packaging. It is not just the food that creates an impact. The packaging, whilst necessary to keep food fresh in some cases, can be a large part of the impact.
Buy locally and seasonally, and encourage them to join a local food network to help them source local and organic seasonal produce direct from local producers. Buying local produce supports local growers and the local economy, and cuts down on food miles.
Grow your own! Set up an organic garden in the school grounds to grow vegetables, fruit, herbs or flowers. Everyone can get involved in practical gardening schemes. The Schools’ Organic Network was set up to encourage and support schools to do this.

To influence government thinking and policy-making, pupils can: