Thursday, 11 August 2016

Our personal energy use matters

A friend recently complained to me that it was pointless trying to save energy at home because our domestic energy use is a tiny proportion of the overall impact from business and industry - whatever we could do personally would not make any difference. This post refutes her statement, at least for the UK. Depending on how you count things, between 25% and 33% of greenhouse gas emissions are due to our activities at home and for personal travel.

The first figure is based on statistics recently released by DEFRA on greenhouse gas emissions by final consumption - this includes emissions due to imported goods and excludes emissions due to imports. The second figure is based on emissions generated within the UK. The chart below shows my best estimates for emissions on personal consumption in 2014. It shows a fairly even split between heating, electricity use, car travel and air travel. Together these add up to 3.7 t COe.

GHG emissions tCO2e/person in 2014 from [1] - details below

Calculating from National statistics for 2014 - 33%
My main source for these figures are National Statistics for greenhouse gas emissions in the UK [1]. However I have made some adjustments to allocate the emissions to personal activities and divided by the population of the UK [2] to get emissions per person.

Activityt CO2e
Home heating1.0Use of gas oil and other fuels in the home
Home electricity0.7The proportion of emissions from power stations due to electricity consumption at home36% of electricity use is domestic [3]
Personal car travel1.0Passenger car use, excluding business travel (but including commuting)14% of car travel is for business from TSGB table 0105 [4]
Air travel1.0A proportion of international air travel due to UK residents travelling for reasons other than business. (I have included a factor for radiative forcing).Use of international aviation bunker fuel from [1], times 1.9 for radiative forcing, times 2 because trips are 2-way and planes refuel abroad to return, times 59% for the proportion of passengers who are UK resident (TSGB table 0124), times 89% to exclude business travel (TSGB table 0124).

The 33% of emissions figure is based on only the first three of these sectors because air travel is not included in the Kyoto protocol emissions and there is no agreement in how it should be counted in national accounts. The total emissions (excluding air travel) per person from this dataset is 8 tCO2e/person.

Calculation from consumption-based statistics for 2013 - 25%
My main source for these statistics is the report from DEFRA on UK's carbon footprint due to consumption [4]. The last year in this dataset is 2013. These statistics are classed as 'experimental' because there is a good deal of underlying uncertainty. Also I have found some inconsistencies which I have reported to DEFRA and I await their response. However my concerns are mainly for earlier years - as far as I can tell 2013 is OK. In that year the total emissions come to 16.4 tCO2e/person.

In these statistics, emissions are allocated based on final demand so they already take into account the fudges I have applied to the final accounts. For example, business air travel by a TV salesman would be allocated to TVs, not to air travel. However, these figures include services provided by free by government (such as the NHS) as well as services purchased by households. The top four categories cover the same sectors as above and they come to 25% of emissions. The table below includes a few more categories - almost 40% of emissions. They are:

Activityt CO2e
Home heating1.3Use of gas oil and other fuels in the home
Air transport services1.0Air travel by householders and public administration
Transport fuel1.0Diesel and petrol bought by householders or public administration
Electricity0.9Electricity bought by householders or public administration
Human health0.8Includes both NHS services and private health services
Food and beverage services0.7Eating out

In these statistics various food categories are separated out. All food together (excluding eating out) comes to 1.6 tCO2e/person, so that would be the largest sector.

Perhaps I should not have been surprised to see construction and health services so high up the table. Our traditional methods of construction are very energy intensive but there is a lot we can do about this (see More houses less bricks and mortar). As for the NHS, this is an area I have not yet investigated so I cannot comment. However, demand on the NHS is increasing. So one thing we can do to reduce carbon emissions is stay healthy as far as possible and die suddenly :-)

Whichever way you count, a significant proportion of GHG emissions are due to our personal activities. Home heating and electricity for appliances, personal car travel and air travel add up to at least 25% of overall emissions. The rest is due to products and services that we buy and consume, especially food, health services and buildings. We do have influence over our environmental impact and there is stuff we can do about it, personally.

[1] Final UK greenhouse gas emissions national statistics: 1990-2014 ( March 2016
[2] Population estimates for the UK ( June 2016
[3] Digest of UK Energy Statistics ( July 2016
[4] Transport statistics Great Britain 2015 ( December 2015
[5] UK's carbon footprint (DEFRA) August 2016

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