Carbon footprint

To limit climate change, it will be essential for each of us to reduce our carbon footprint individually and collectively. As the principal greenhouse gas is carbon dioxide, the term carbon footprint is used to describe this impact which is related to the amount of gas(es) emitted by any use of energy. The greater the emissions, the larger is the footprint and so this concept enables us to determine which activities have a high impact and to identify alternatives which will have a lower footprint.

Our carbon footprint comprises two parts – one part is associated primarily with our own use of energy and the other part which is associated with the food that we eat, the products we use or the clothes that we buy; this is called the embedded or indirect part. This latter part arises from the energy used with growing crops, extracting raw materials, processing and/or manufacturing a product and the transport associated from the point of growing/manufacture to the place of use. It is much more difficult to calculate as it requires knowledge of the energy usage and other inputs along the supply chain from growing or extracting raw materials to purchasing a product.

Annual energy consumption and carbon emissions

Our own (direct) energy usage and associated emissions are analysed in the accompanying pie charts from data collated by Mike Berners-Lee, Burning Question (Profile Books, 2013).

How energy is consumed in and around the home in UK

Space heating and car usage are the biggest uses of energy and largest emissions followed by water heating and electricity use.

So in terms of reducing our carbon footprint, we can conclude that -

• more thermal insulation of our dwellings will reduce emissions significantly
• improvements in public transport will reduce car usage
• energy demand associated with water heating could be reduced by taking showers rather than baths
• reducing our electricity consumption can be best achieved by buying more energy efficient appliances when these need to be replaced

Direct and indirect emissions

Our direct emissions relate to the energy each of us uses while our indirect emissions are associated with the products we buy, the food we consume and the infrastructure and services we use.
As can be seen from the Table, our indirect emissions are similar to our direct emissions. Thus reducing our indirect emissions is as important as reducing our direct emissions and this can generally be best achieved by buying products produced or manufactured locally and using local energy sources.

Average energy use (kWh) and carbon emissions (kg CO2) per person per year in the UK

Thus on average, each person in the UK is responsible for the equivalent of 10.6 tonnes of carbon dioxide, which includes both the direct and indirect emissions associated with energy usage.

Calculating your carbon footprint

Many websites offer tools to help you measure your carbon footprint. Most focus on direct emissions such as energy bills and fuel consumption while ignoring indirect emissions associated with products and services.

Sites worth exploring are –

• Carbon Footprint Ltd - Carbon Footprint Calculator www.carbonfootprint.com/calculator.aspx
• WWF Footprint Calculator - www.footprint.wwf.org.uk/
• Carbon footprint calculator - www.carbonindependent.org/
• Simple Carbon Calculator  NEF - www.carbon-calculator.org.uk/