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Next steps for carbon footprint calculators

Next steps for carbon footprint calculators




This is to make four points about personal carbon footprint calculation:

  1. First, cynics notwithstanding, personal carbon footprint calculation has value, to incentivise behaviour change and also to open conversations about needed system change;
  2. Second, there are standards an ideal online calculator should meet;
  3. Third, it is hard to find a tool which ticks all the necessary boxes; and
  4. Fourth, the building blocks are available to do better.


Personal carbon footprint calculation has value

Let’s not waste much time making the case for personal carbon footprints.

There are plenty of cynics. They point out that calculators were originally invented by the fossil fuel industry as a way to divert attention from its own responsibility in creating climate havoc. In a widely cited article, Mark Kaufman points the finger at BP in the early 2000s, aided and abetted by the advertising agency Ogilvy and Mather. Critics argue that focusing on personal responsibility and action distracts from the bigger issues, which are to do with ‘system change’: urban re-design, for example, to offer more cycle routes, or reformed tax codes, so that polluters bear the cost of carbon emissions. Even those less cynical might argue that carbon footprinting is complicated and time-consuming.

On the other hand, personal footprinting can be revelatory. It can incentivise people to make better decisions about their own consumption. Is my footprint really that big? What is easy for me? What is difficult? It is a way to get beyond overarching slogans like ‘Reduce, Reuse, Recycle’, ‘Avoid, Shift, Improve’, or my own improved formulation, ‘Shrink, Shift, Shuffle’.

Furthermore, footprinting can be useful open a conversation about wider system change What does the Government need to do to help me reduce my footprint? In energy supply? Or building codes? Or food production?

Of course, there is a literature on the psychology of target-setting. I googled this, and the first hit was a piece on the psychology and science of goal-setting, by Madhuleena Roy Chowdhury. She says

‘Goal-setting in psychology is an essential tool for self-motivation and self-drivenness – both at personal and professional levels. It gives meaning to our actions and the purpose of achieving something higher.

By setting goals, we get a roadmap of where we are heading to and what is the right way that would lead us there. It is a plan that holds us in perspective – the more effectively we make the plan, the better are our chances of achieving what we aim to. . . Setting goals (is) linked with higher motivation, self-esteem, self-confidence, and autonomy, and research has established a strong connection between goal-setting and success.

So, that’s all right, then. Personally, I think of a carbon footprint tracker as being analogous to a Fitbit watch, or similar, used to monitor health and training regimes. If I can count steps, why can’t I find some way to count carbon?

It is worth saying that companies and partnerships in the UK are required by law to measure carbon emissions and set targets, for Scope 1 and 2 emissions, and ideally also for Scope 3 (supply chain- and impact-related) (for definitions of Scopes 1.2 and 3, see Ch 5 of our Counting Carbon report, and the WRI Figure cited in that report below). So, it should not be too disorienting to apply the same principles to personal emissions.

Figure 1

Scope 1,2 and 3 emissions

Standards for an online calculator

My interest is in online calculators that anyone can use, at home, in schools, or community groups.

Everyone will have different requirements, but we can start with the criteria recommended by the UK business reporting guidance (SECR), that reporting should be:

  • Relevant
  • Quantitative
  • Accurate
  • Complete
  • Consistent
  • Comparable
  • Transparent

My own list for personal and user-friendly footprinting would modify and expand as follows, recognising some inevitable trade-offs:

  • Simple
  • Expandable
  • Updateable
  • Household-based
  • Comparative
  • Linked to local action

What do I mean by these additional criteria?

  • Simple means that a calculator should cover all key areas (housing, food, transport, clothing, ‘stuff’, leisure, and so on), but should not, in the first pass, require detailed parsing of household budgets. People need a rough idea to start with and do not want to be poring over gas and electricity bills, trying to separate out estimated from actual meter readings.
  • Expandable, though, means that there is an option to be more accurate in a second stage, if people want to know more. Don’t throw away those old bills!
  • Updateable means that the calculator should retain information and allow for regular updating.
  • Household-based - because that is how people live. My household and I heat the house together, and eat together and drive together, and mostly spend our leisure time together etc . . . It is much easier for people to calculate at the household level. And, most important, there are methodological reasons to start at the household level and disaggregate to individuals. This is an issue well known to statistical offices, and to do with the economies of scale of living with others.
  • Comparative - because it is really helpful for comparative purposes to stratify the population by demography and geography, ideally including income. Thus, how does ‘our’ carbon footprint compare with others in our area who also have a household income of +/- £x, with two pre-school children? Or how does our carbon footprint compare with other retired couples?
  • Linked to local action. This means that there is guidance available via the tool on what to do to reduce the carbon footprint, and also how to do it: links to local suppliers, for example, with reviews.

Of the additional criteria, the two most challenging are to be household-based and comparative.

To make this personal, calculators I have tried give my own carbon footprint at around the UK average. That is a lot, disappointingly, but I don’t quite trust the number, because of the data manipulations required to get from our household activities to an individual footprint. For example, most of the time, there are two of us in the car, and that is not taken into account. Am I supposed to ‘play’ the calculator by reducing the annual distance I say I travel? Also, I would really like to know whether my own footprint is in line with ‘people like me’, in my area, for example, or with a similar demographic profile.

It goes without saying that the standards I have suggested are not straightforward. Calculating a footprint is already very hard, given data uncertainties on topics like the energy mix or the carbon content of nominally similar consumption baskets. For example, it matters a lot what is the share of green electricity supplied to the national grid. So, it does not help to add new criteria, especially if highly disaggregated by demography and geography. But I will argue below that quite a lot can be done – and has already been done.

Are available footprinting tools up to scratch?

There are many footprinting tools available, and some excellent comparative reviews, for example by Footprint Hero, One Home, the Centre for Alternative Technology, and Greenly Resources. Some calculators are very general, some are more detailed. Some use UK data, some do not. Some have detailed advice on next steps, some do not.

I looked particularly at 5 calculators, each recommended by one of the review sites, and scored them against my supplementary criteria (Table 1). Don’t consider this the last word: it was a cursory look. However, none of the calculators quite fitted the bill.

Table 1

The Cool Climate calculator, which comes from Berkeley in the US, is excellent and ticks most of the boxes – a screenshot of the home page is pasted in below. It is easy to use, provides results at the household level, and has useful demographic/income comparators. Unfortunately, however, it is based on US data.

Figure 2


Of the others, the closest match is the WWF calculator, which comes in two versions, a web version and one as an apple or android app designed for phone or tablets. The app version is much more heavily populated with articles and challenges. Both are based on UK data and are easy to use in the first instance, with options for more detailed calculation. The calculator offers the option of comparing your result with others in the same neighbourhood – though in my case, there were no results to compare with. Unfortunately, the calculator does not offer a household option, and does not offer links to local resources.

For me, the biggest gap in UK-focused calculators is the lack of a household option. Some offer a simple division of some of the results by the number living in the household, but this is not consistent with usual statistical practice, and so gives a misleading result. The demographic comparators are also weak. None, that I have found, offers what the Cool Climate calculator does, a comparison with ‘households with same size and income’. We could add geographical area to that.

The building blocks are available to do better

So, there are three improvements I would like to see to UK-focused calculators. These are (a) household as well as individual results, (b) better demographic and geographical comparators, and (c) better links to local resources.

The building blocks are available, at least for the first two.

Household as well as individual results

First, then, household as well individual results. As noted earlier, it is much easier to calculate at the household level, and also it is better to start with the household because there are economies of scale in living with others. The OECDOrganisation for Economic Cooperation and Development recognises this and recommends the use of ‘equivalence scales’. It says

The needs of a household grow with each additional member but – due to economies of scale in consumption– not in a proportional way. Needs for housing space, electricity, etc. will not be three times as high for a household with three members than for a single person. With the help of equivalence scales each household type in the population is assigned a value in proportion to its needs. The factors commonly taken into account to assign these values are the size of the household and the age of its members (whether they are adults or children).

There are different versions of equivalence scales, summarised in Table 2. The UK Office of National Statistics (ONS) uses the ‘OECD modified scale’ when calculating both household and individual income distribution (see here).  

Table 2

Alternative equivalence scales

Presumably, various adjustments would be needed when calculating household and individual carbon footprints. For example, it would be appropriate to adjust for housing and food costs, but not for flights or train travel: in those cases, everyone occupying a seat should have their carbon counted.

I haven’t checked to see how different calculators handle the fine adjustment.

And presumably, the same or different equivalence standards apply in different countries?

Demographic and geographical comparators

Second, demographic and geographical comparators: the question of how ‘our’ footprint compares with that of others like us. Some of the calculators reviewed do offer comparisons, though usually at a very general level: for example, the country average. WWF offer the possibility of a postcode comparator, but thinly populated at present.

A great source for initial comparison in England, with geographical but only limited disaggregated demographic information, is the Leeds University Place-Based Carbon Calculator. This calculates average carbon emissions for each person in each of 33,755 small areas of 1500-3000 people called Lower Super Output Areas (LSOAs), the smallest unit in the geographical database maintained by the Office for National Statistics. Malcolm Morgan describes the impressive work underpinning the calculator here, and discusses the results.

An example of the information provided is below, for an LSOA in Brighton (NB not quite where I live). This is an area known as ‘muesli mountain’, with three Green Party councillors. Nevertheless, the area only scores C- overall, with an average footprint of 7.5 tons per person. This is below the national and local authority average, but above similar LSOAs.

Figure 3

There are obviously assumptions made in the calculation, not least the number of flights, which accounts for a large share of the overall footprint. The data page of the calculator says that ‘to attribute the England flight emissions to LSOA we used research on the Gini coefficient of flying in England by Milena Buchs and data on the average household incomes to apportion out the emissions (to) each LSOA. Finally these are divided by the resident population to give an emissions per person estimate.’

Note also that the per capita data are simple averages, and do not take account of household equivalence. Further work on income distribution and expenditure data would be possible, using the many data sets on expenditure by region, income level and household composition produced by the ONS.

Nevertheless, the Leeds calculator is a truly amazing resource. Is something similar available in other countries?

Better links to local resources

Finally, links to local resources. Pretty well all the calculators reviewed link to advice on how to reduce the footprint, often with personalised challenges and targets. Consume less, insulate the house, eat less red meat and dairy, use public transport, check for low carbon options when shopping. . . ‘Shrink’, one might say, ‘shift’, and ‘shuffle’ (see here).

The next step, however, is to make this local. House insulation? Great idea, but which suppliers are available in my local area? A heat pump? Who do you recommend? Non-meat burgers or vegetarian cheese? What do you recommend?

A model for this is something like the Money Saving Expert website, founded by Martin Lewis. This provides information and advice, with tips and best-buy recommendations. However, unlike some other sites,

‘The site never charges to save people money, nor does it take any advertising. Companies cannot pay to buy space on the site (see the How this site is financed guide for more info). Any top deals, best buys, tips or suggestions on the main site are purely down to journalistic research from the MSE team and Martin (see the Editorial Code).

Could we do this for climate action, locally? And, again, in different countries?


For me, this is the beginning of a journey – so apologies to the experts for errors and misunderstandings. I have been interested in consumption emissions (see this piece from 2019, and the Counting Carbon report I put together with Aarti Krishnan), and am working separately on individual carbon budgets for 1.5 or 2 degrees (blog to follow). I completely understand that ‘system change’ is central to tackling emissions and that all responsibility cannot be devolved to individuals: this came out strongly in the chapter on low carbon lifestyles of the 2020 UN Environment Emissions Gap Report, led by Stuart Capstick, Radhika Khosla and Susie Wang. I also understand that inequality is a major problem with respect to emissions: the World Inequality Report has been especially useful on this, drawing on work by Lucas Chancel. However, individual action has a role to play and carbon footprinting can contribute to that.

(Thanks to Joanne Nightingale and Devon Moore at WWF for discussion of the WWF calculator; and to two of the gurus in this field, Dr Malcom Morgan and Dr Anne Owen, both at the University of Leeds, for advice and pointers. Of course, responsibility for misinterpretations and errors is mine)

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