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My Carbon Footprint - 2006

by James Lea, 23 January 2007

This article describes my carbon footprint for the year 2006 - the amount of carbon dioxide my lifestyle produced in that year. A carbon footprint is a vital tool for helping reduce our greenhouse gas emissions, and is an essential step on the way to a low carbon economy.

My footprint is low, because I have taken many measures to reduce my carbon dioxide emissions. However, it is not low enough to satisfy the Contraction & Convergence principles necessary to prevent dangerous climate change. Clearly, I must continue to reduce my footprint, and this carbon audit is an essential step on the way.

What is a Carbon Footprint?

A carbon footprint is a simple concept - it is the total mass of carbon dioxide emitted as a consequence of a person's activities over a year. The figure is commonly cited in kilogrammes per year, or tonnes per year, depending on how large the number is.

Because so many different activities contribute to an individual's carbon footprint, it is important to understand what has been measured when a figure is quoted. Without this understanding, it is difficult to compare footprints. For this reason you should also give a breakdown, as I have done below.

There is one other complication - carbon dioxide is not the only greenhouse gas that contributes to global warming. Among others, methane is the most significant gas, and is produced by landfill and cattle farming, to name but two. This has been taken into account for food consumption and waste production.

How I calculated my Carbon Footprint for 2006

To work out my 2006 Carbon Footprint, I measured these aspects of my lifestyle:

  • Electricity, gas and water consumption
  • Distance commuted, including mode of transport
  • Leisure journeys, including flights
  • Where I buy my food from
  • The amount of waste I produce that cannot be recycled.

For gas and electricity these figures were calculated from actual meter readings. I've divided these by two, to account for my share between the two of us living at home.

For travel to and from work, I've estimated the number of journeys made and their distance, then scaled that up by the amount of CO2 emitted for that mode of transport. I've used a similar approach for calculating the impact of leisure journeys.

Some figures are difficult to calculate directly, as they represent embodied energy, and hence embodied CO2. For instance, when buying food from a supermarket you may not travel any further than your local shops, but the food is likely to have been freighted up and down the country (one-third of lorries on the motorways are carrying food for supermarkets!).

Electricity: 0.08 tonnes CO2

In 2006 we consumed 1981 kWHr of electricity. Of this, 356 kWHr was from a non-renewable supplier, and the remainder from Good Energy, a 100% renewable supplier.

Each kWHr of non-renewable electricity creates 0.45 kgCO2 [Electricity], so 356 kWHr created 160 kgCO2. My personal share was half this, just 80 kgCO2.

Gas: 1.69 tonnes CO2

In 2006 we burnt 17804 kWHr of natural gas heating our home, hot water, and cooking. Each kWHr of natural gas creates 0.19 kgCO2 [Gas], making a total of 3383 kgCO2. My personal share was half of this, equal to 1691 kgCO2.

Water: 0.03 tonnes CO2

Water consumption is a good example of embodied CO2 - there's no apparent production of CO2 when you turn the tap, but it takes a considerable amounts of energy for your water supplier to collect water, purify it, pump it to your home, pump the resulting sewage away, treat it and dispose of it! Each tonne of water processed in this way requires 0.91 kWHr of energy, causing 0.41kgCO2 [Water].

In 2006 we didn't have a water meter fitted to our home, so I couldn't directly measure water consumption. However, from previous figures collected when we had a similar lifestyle, this was around 12 tonnes of water per month, or 144 tonnes per year. Given that each tonne liberates 0.41kgCO2, our water consumption for 2006 was responsible for 59kgCO2. My share of this was 30kgCO2.

Commuting: 0.43 tonnes CO2

We don't own a car, and make most of our journeys by public transport. I commute to work by train, a round-trip distance of 40 miles. In 2006 I made 150 return journeys to work, a total distance of 6000 miles.

I travel on a Class 153/1 diesel commuter train which produces, for every mile travelled, around 2.2 kgCO2 [Commuter Train]. However, my commuter service is rammed full of passengers (thanks to First Great Western), and carries around 50 passengers in two carriages (making this an energy efficient mode of transport, despite the discomfort). This means that my journey causes 1/50th of 2.2 kgCO2 / kilometre, which is 0.044 kgCO2 / passenger kilometre.

Travelling 6000 miles, or 9654 kilometres, my CO2 emissions were 0.044 kgCO2 / passenger kilometre * 9654 kilometres = 425kgCO2.

Leisure journeys: 0.40 tonnes CO2

I made no flights last year, having given up flying because of its environmental impact.

However, we occasionally hire a car to visit family or go on holiday, for which we travelled about 2000 miles in 2006. This car emits around 0.2kgCO2 / kilometre [Small car], or 0.3kgCO2 / mile, making a total of 667 kgCO2. For a journey made by two, my share is half this, or 334 kgCO2.

We also travel by InterCity train to visit friends and family, and covered around 1000 miles (1609km). An InterCity train emits 12.17 kgCO2 / kilometre [InterCity Train]. Assuming 8 passenger cars, each carrying 40 passengers on average, each train carries around 320 passengers. Each passenger is therefore responsible for 1/320th of 12.17 kgCO2 / kilometre, equivalent to 0.038kgCO2 / passenger kilometre.

Covering 1609 km in an InterCity 125, my CO2 emissions were 1609 * 0.038kgCO2 / passenger kilometre = 61 kgCO2.

  • Total leisure activity emissions = 334 + 61 kgCO2 = 395kgCO2.

Food and drink: 0.7 tonnes CO2

We buy most of our food from a local organic market stall, or from Riverford Organics' home box delivery scheme. We totally avoid airfreighted food, and minimise our consumption of exotic fruits (bananas are one thing we cannot give up, yet.). Our emphasis is on local food to minimise embodied energy.

The Independent newspaper [Food] reports that a typical UK resident produces 1.39 tonnes CO2 from food production and transport, both national and international. I estimate that local food production and consumption halves this figure, and on that basis, estimate my food and drink in 2006 caused 0.7 tonnes CO2 to be emitted.

Waste: 0.3 tonnes CO2

We compost all food waste. Over 2006 this rotted down to 15 large bags of top quality compost, used to mulch our raised vegetable bed. Glass, paper, tin foil, plastics etc. are recycled via the council's recycling collection.

We are members of a local 'freecycle' email list, where members can swop unwanted items without charge. We recently gave away a filing cabinet we no longer needed - it found a new home in an office, instead of ending up as scrap, or worse still, landfill.

We also take care to buy good quality products that will last, even if they cost more in the first place. This minimises the energy cost of disposing or recycling an appliance or item.

I estimate my share of waste production at 0.3 tonnes CO2 for 2006.

Overall Footprint for 2006: 3.64 tonnes CO2

My 2006 carbon footprint was, in tonnes of CO2:

  • Electricity - 0.08
  • Gas - 1.7
  • Water - 0.03
  • Commuting - 0.43
  • Leisure journeys - 0.40
  • Food and drink - 0.7
  • Waste - 0.3

making for a grand total of 3.64 tonnes CO2. This is very low compared to the average UK citizen's carbon footprint of around 11 tonnes CO2 per year [Independent Newspaper]!

Next Steps

Having selected a renewable energy supplier, given up flying, and using public transport, there are two key areas left for me to focus on:

  1. Minimising my gas consumption; and
  2. Growing more of my own food.

I intend to minimise gas consumption by taking the following steps (in this order):

  1. Fitting an energy-efficient gas condensing boiler;
  2. Installing a wood burning stove, and using biomass to heat the home (biomass is almost carbon-neutral);
  3. Fitting solar hot water panels.

In the longer run more radical steps will be needed, and will require support through favourable government policies. For example, at present I have to commute 6000 miles a year (or more) because I cannot afford to live where I work (in a major city). Clearly, the UK's absurd overpriced housing market directly contributes to climate change, because it forces people to commute greater distances.

The solutions are simple, but require fundamental changes, such as a) regulating house prices (in much the same way that energy prices are regulated), and b) reforming UK planning law to allow ecological development (ie without cars, and in proximity to local jobs, food supply and services) across the country. However, neither of those measures are palatable at the moment, but doubtless climate change will alter this perception in time!

 

Appendix - Data Sources

Useful conversions

Kilometres to miles = 1.609

Electricity

Source: Mayer Hillman, How we can save the Planet.

Gas

Source: Mayer Hillman, How we can save the Planet.

Water

Correspondence with David Wilks, inventor of the Interflush water saving device (www.interflush.co.uk). He cited figures obtained by Sheffield University researchers 1998-9.

Commuter train

Data available from Final Report, Rail Emission Model, November 2001, produced for the Strategic Rail Authority by AEA Technology as follows:

  • Class 153/0 is one power car, emitting 1.415kgCO2/km
  • Class 156 is 2 power cars, emitting 2.234 kgCO2/km

My regular comuter train is a class 153/1 with two power cars (and no trailer cars), so I have assumed 2.2 kgCO2/km.

Intercity Train

According to the Final Report, Rail Emission Model, November 2001, produced for the Strategic Rail Authority by AEA Technology :

  • InterCity 125 produces 12.17kgCO2/km

Small car

Source data: manufacturers' figures published below car adverts. These range from 120gCO2/km to 200gCO2/km. I have used the pessimistic end of the scale.

Food

Independent Newspaper Saturday 9 December 2006 - cover page article 'Your carbon footprint revealed'.

 

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