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Carbon Methodology

How does the One Small Step Carbon Footprint Calculator work?

Our carbon accounting system is a work in progress. While we’ve put a lot of work and thought into the current model, its accuracy is constrained by:

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  1. the information we can collect from you in order to predict your environmental impact; and

  2. the reliance we have presently on self-reporting by users without access to real-world data on things like your energy usage, car usage or kgs of waste you create each week. 

 

That said, we think the model we’ve built is promising and is only going to get better with time, especially as we look to partner with organisations where we can collate observed data. For example, with your consent, integrating your energy usage numbers through a partnership with your energy provider, or asking questions that help us figure out exactly how often you’re driving your car and it’s fuel efficiency. 

 

We’ve outlined the methodology we’ve used below to calculate your quiz results in the One Small Step app, and the default assumptions we’ve used to figure out the environmental impact you can achieve by completing the current programs in the One Small Step app. 

 

We are continuously improving this calculator, and we will update this page with changes to our model as we augment it. 

Calculating your carbon footprint: methodology and assumptions

We combine the information you provide in your answers to the on-boarding quiz and Australian Bureau of Statistics (ABS) census reports on Australian income, expenditure, water & electricity usage to get a highly detailed breakdown of what your consumer habits are likely to be. These figures are influenced by what state you live in, how many people you live with, and what income bracket your household applies to. 

 

We then run these energy, water, gas, fuel, food & spending figures through a consumption-based accounting model provided by Tomorrow co. to create an annual carbon dioxide equivalent (CO2e) footprint score in each category. This model is used globally and provides localised conversion factors for many countries, including Australia. We then take care to improve accuracy by using recent, Australian-specific data in place of global averages.

 

The CO2e footprint data we use is based on ‘full life-cycle analysis’, meaning it takes into account the CO2e produced during material processing, manufacturing, distribution, use, recycling & final disposal of the things you consume. This paints a more complete picture of the effort and  consequences behind consumer goods & services, allowing for more impactful decision-making when trying to reduce our carbon footprint.

  • What is CO2e?
    Carbon dioxide (CO2) is not the only greenhouse gas that contributes to climate change, but it is one of the easiest to understand, visualise and use in comparisons. CO2 equivalence (CO2e) is the method of converting all other greenhouse gases emitted during production and consumption of goods and services, like methane & nitrous oxide, to their equivalent value in CO2. This gives us a fair look at the relative impact of our actions in simpler terms.
  • Why do you use a consumption-based accounting model?
    We don’t believe you should be responsible for the emissions of all the products your country exports – only for what you consume. We wish to inform and empower you as a consumer, because ultimately the demand of goods and services is in your control. Using a consumption-based accounting model (CBA) also retains accuracy in instances where governments relocate dirty production to nearby countries to maintain a ‘green’ image.
  • What is the end goal?
    It is not too late to mitigate the effects of climate change. Taking into account population growth and natural carbon sinks, the UN estimates that if we reduce our individual yearly footprint to 2 tonnes C02e by 2050, we can limit global warming to 2 celsius by 2100. The ecological and societal outcomes of meeting this target are vast, and our capacity to achieve it improves each year as sustainable energy, transport & food become widespread. If you’d like to find out more, check out the UN Paris Agreement & Global Sustainability Report.
  • Energy
    We use information about your household type, number of residents, occupancy status, income and location to determine which of five electricity usage groups, detailed in the ABS residential electricity usage survey, you would most likely belong to. Your annual usage, (measured in KiloWatt hours, or KWH) is then adjusted to account for any gas water heating, carbon offsetting & sustainable energy sources. Tomorrow co. provides a carbon intensity measurement per KWH for each Australian state (or per MJ – megajoule – if energy source is gas). These have been calculated using real-time consumption statistics and a full lifecycle analysis of each energy production technology provided by the Intergovernmental Panel on Climate Change. We then multiply carbon intensity by your estimated annual KWH usage to get your final energy score. This score is then distributed according to yourhome.gov estimates on energy consumption, giving us a look at how much energy can be attributed to appliances, climate, water heating, lighting etc.
  • Transport
    Tomorrow co. provides full lifecycle carbon modelling for each transport type per kilometer travelled (e.g. petrol car, hybrid, bicycle, walking etc). Calculations are also distinct for domestic and international flights, as their average air speed, capacities, efficiency & cargo ratios differ. The information you provide allows us to calculate the total distance travelled annually and therefore the total carbon intensity transport score. Options in the onboarding quiz that are a combination of multiple transport methods are calculated using the mean average intensity of those methods. (i.e. Public transport is the average of trains and buses per kilometer travelled).
  • Purchases
    Referring to your income estimates, we are able to use the ABS household expenditure survey to determine a breakdown of the goods & service expenses you are likely to have. This allows us to estimate the annual carbon intensity of individual products (such as light bulbs), or broader product categories (household durables), depending on the context. These figures are adjusted depending on which state you live in & whether you often purchase second hand. We then map these expenses to a product database provided by Tomorrow co. which estimates the carbon intensity of each Australian dollar spent in those product areas. Some examples of the products and services we are calculating the carbon intensity of are: financial services, clothing, appliances, durables, furnishings, cleaning equipment, electronics, toiletries and so on. We intend to continually add detail to this category as new data becomes available.
  • Food
    We calculate carbon intensity on a per meal basis, using the diet information you have provided. Each diet type has its own adjusted carbon intensity value provided by Tomorrow co., which takes into account age and sex in calculating an average daily intake. The values are further adjusted depending on whether you eat beef and/or dairy and if the food is sustainably sourced. We then calculate the carbon intensity of alcoholic & non alcoholic beverages using the same method as detailed in the purchases category, and add that to get the final score.
  • Waste
    We start with the Australian household food & plastic waste averages, add in any disposables from the purchases category (e.g. paper towels, toilet paper etc) and then calculate the carbon intensity using the figures provided by the Tomorrow co. products database. We use adjusted life cycle stats for each waste material type, including average recycling rates. Your final score is then offset by the percentage of your food that is unpackaged & whether you compost your food waste.
  • Water
    The Bureau Of Meteorology estimates the carbon footprint of supplying Australian homes with water in each major district in the urban national report for water utilities. We take the mean of all major districts in each state to get a state average. This does not include the intensity of heating the water, so we have subtracted the total intensity of water heating (gas or electric) from the energy category and added it here for a more accurate look. We then distribute the score using yourhome.gov estimates to determine what percentage can be attributed to outdoor use, showers, toilet, laundry etc.

Calculating the estimated impact of One Small Step programs & habits

We have made a series of assumptions about the impact of our existing carbon footprint reduction programs & habits. These are outlined here. All data sources listed are publicly accessible. We think the assumptions we’ve made to calculate program impacts are reasonable and also relatively conservative. 

 

However we’ll be able to rapidly improve the accuracy of our assumptions with regard to program impacts when we introduce a feature that provides our users with more granular control over their personal carbon profile. Until then, wherever the onboarding profile lacks detail, we use built-in default assumptions about user behaviour and how often users carry out specific pro-environmental behaviour as a result of completing One Small Step programs & habits.

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Impacts scale to fit your existing carbon footprint profile
 

For different users, actions will have different impacts. This is because One Small Step users have different carbon footprint profiles that affect the potential impact of different programs & habits.

 

Here’s an example of how this works: 

 

Mike uses the One Small Step app. When he does the quiz, he reports that he is a regular meat eater. When Mike completes the ‘Discover Plant-based Food’ challenges and starts switching to vegan alternatives, we assume he commits to eating two vegan meals per month for 2 months. By calculating the difference in intensity of those vegan meals as compared to his current diet we are able to estimate his impact.

 

When Chrissy does the quiz, she reports that she is a vegetarian. By using her current diet in the calculation, we get a lower, but more accurate, potential impact for Chrissy than for Mike.

 

This convention is used wherever possible to help keep the total impact of completing programs consistent with who you are, and the sustainable habits you already have committed to prior to coming into the app.

  • What is CO2e?
    Carbon dioxide (CO2) is not the only greenhouse gas that contributes to climate change, but it is one of the easiest to understand, visualise and use in comparisons. CO2 equivalence (CO2e) is the method of converting all other greenhouse gases emitted during production and consumption of goods and services, like methane & nitrous oxide, to their equivalent value in CO2. This gives us a fair look at the relative impact of our actions in simpler terms.
  • Why do you use a consumption-based accounting model?
    We don’t believe you should be responsible for the emissions of all the products your country exports – only for what you consume. We wish to inform and empower you as a consumer, because ultimately the demand of goods and services is in your control. Using a consumption-based accounting model (CBA) also retains accuracy in instances where governments relocate dirty production to nearby countries to maintain a ‘green’ image.
  • What is the end goal?
    It is not too late to mitigate the effects of climate change. Taking into account population growth and natural carbon sinks, the UN estimates that if we reduce our individual yearly footprint to 2 tonnes C02e by 2050, we can limit global warming to 2 celsius by 2100. The ecological and societal outcomes of meeting this target are vast, and our capacity to achieve it improves each year as sustainable energy, transport & food become widespread. If you’d like to find out more, check out the UN Paris Agreement & Global Sustainability Report.
  • Energy
    We use information about your household type, number of residents, occupancy status, income and location to determine which of five electricity usage groups, detailed in the ABS residential electricity usage survey, you would most likely belong to. Your annual usage, (measured in KiloWatt hours, or KWH) is then adjusted to account for any gas water heating, carbon offsetting & sustainable energy sources. Tomorrow co. provides a carbon intensity measurement per KWH for each Australian state (or per MJ – megajoule – if energy source is gas). These have been calculated using real-time consumption statistics and a full lifecycle analysis of each energy production technology provided by the Intergovernmental Panel on Climate Change. We then multiply carbon intensity by your estimated annual KWH usage to get your final energy score. This score is then distributed according to yourhome.gov estimates on energy consumption, giving us a look at how much energy can be attributed to appliances, climate, water heating, lighting etc.
  • Transport
    Tomorrow co. provides full lifecycle carbon modelling for each transport type per kilometer travelled (e.g. petrol car, hybrid, bicycle, walking etc). Calculations are also distinct for domestic and international flights, as their average air speed, capacities, efficiency & cargo ratios differ. The information you provide allows us to calculate the total distance travelled annually and therefore the total carbon intensity transport score. Options in the onboarding quiz that are a combination of multiple transport methods are calculated using the mean average intensity of those methods. (i.e. Public transport is the average of trains and buses per kilometer travelled).
  • Purchases
    Referring to your income estimates, we are able to use the ABS household expenditure survey to determine a breakdown of the goods & service expenses you are likely to have. This allows us to estimate the annual carbon intensity of individual products (such as light bulbs), or broader product categories (household durables), depending on the context. These figures are adjusted depending on which state you live in & whether you often purchase second hand. We then map these expenses to a product database provided by Tomorrow co. which estimates the carbon intensity of each Australian dollar spent in those product areas. Some examples of the products and services we are calculating the carbon intensity of are: financial services, clothing, appliances, durables, furnishings, cleaning equipment, electronics, toiletries and so on. We intend to continually add detail to this category as new data becomes available.
  • Food
    We calculate carbon intensity on a per meal basis, using the diet information you have provided. Each diet type has its own adjusted carbon intensity value provided by Tomorrow co., which takes into account age and sex in calculating an average daily intake. The values are further adjusted depending on whether you eat beef and/or dairy and if the food is sustainably sourced. We then calculate the carbon intensity of alcoholic & non alcoholic beverages using the same method as detailed in the purchases category, and add that to get the final score.
  • Waste
    We start with the Australian household food & plastic waste averages, add in any disposables from the purchases category (e.g. paper towels, toilet paper etc) and then calculate the carbon intensity using the figures provided by the Tomorrow co. products database. We use adjusted life cycle stats for each waste material type, including average recycling rates. Your final score is then offset by the percentage of your food that is unpackaged & whether you compost your food waste.
  • Water
    The Bureau Of Meteorology estimates the carbon footprint of supplying Australian homes with water in each major district in the urban national report for water utilities. We take the mean of all major districts in each state to get a state average. This does not include the intensity of heating the water, so we have subtracted the total intensity of water heating (gas or electric) from the energy category and added it here for a more accurate look. We then distribute the score using yourhome.gov estimates to determine what percentage can be attributed to outdoor use, showers, toilet, laundry etc.
  • What is CO2e?
    Carbon dioxide (CO2) is not the only greenhouse gas that contributes to climate change, but it is one of the easiest to understand, visualise and use in comparisons. CO2 equivalence (CO2e) is the method of converting all other greenhouse gases emitted during production and consumption of goods and services, like methane & nitrous oxide, to their equivalent value in CO2. This gives us a fair look at the relative impact of our actions in simpler terms.
  • Why do you use a consumption-based accounting model?
    We don’t believe you should be responsible for the emissions of all the products your country exports – only for what you consume. We wish to inform and empower you as a consumer, because ultimately the demand of goods and services is in your control. Using a consumption-based accounting model (CBA) also retains accuracy in instances where governments relocate dirty production to nearby countries to maintain a ‘green’ image.
  • What is the end goal?
    It is not too late to mitigate the effects of climate change. Taking into account population growth and natural carbon sinks, the UN estimates that if we reduce our individual yearly footprint to 2 tonnes C02e by 2050, we can limit global warming to 2 celsius by 2100. The ecological and societal outcomes of meeting this target are vast, and our capacity to achieve it improves each year as sustainable energy, transport & food become widespread. If you’d like to find out more, check out the UN Paris Agreement & Global Sustainability Report.
  • Energy
    We use information about your household type, number of residents, occupancy status, income and location to determine which of five electricity usage groups, detailed in the ABS residential electricity usage survey, you would most likely belong to. Your annual usage, (measured in KiloWatt hours, or KWH) is then adjusted to account for any gas water heating, carbon offsetting & sustainable energy sources. Tomorrow co. provides a carbon intensity measurement per KWH for each Australian state (or per MJ – megajoule – if energy source is gas). These have been calculated using real-time consumption statistics and a full lifecycle analysis of each energy production technology provided by the Intergovernmental Panel on Climate Change. We then multiply carbon intensity by your estimated annual KWH usage to get your final energy score. This score is then distributed according to yourhome.gov estimates on energy consumption, giving us a look at how much energy can be attributed to appliances, climate, water heating, lighting etc.
  • Transport
    Tomorrow co. provides full lifecycle carbon modelling for each transport type per kilometer travelled (e.g. petrol car, hybrid, bicycle, walking etc). Calculations are also distinct for domestic and international flights, as their average air speed, capacities, efficiency & cargo ratios differ. The information you provide allows us to calculate the total distance travelled annually and therefore the total carbon intensity transport score. Options in the onboarding quiz that are a combination of multiple transport methods are calculated using the mean average intensity of those methods. (i.e. Public transport is the average of trains and buses per kilometer travelled).
  • Purchases
    Referring to your income estimates, we are able to use the ABS household expenditure survey to determine a breakdown of the goods & service expenses you are likely to have. This allows us to estimate the annual carbon intensity of individual products (such as light bulbs), or broader product categories (household durables), depending on the context. These figures are adjusted depending on which state you live in & whether you often purchase second hand. We then map these expenses to a product database provided by Tomorrow co. which estimates the carbon intensity of each Australian dollar spent in those product areas. Some examples of the products and services we are calculating the carbon intensity of are: financial services, clothing, appliances, durables, furnishings, cleaning equipment, electronics, toiletries and so on. We intend to continually add detail to this category as new data becomes available.
  • Food
    We calculate carbon intensity on a per meal basis, using the diet information you have provided. Each diet type has its own adjusted carbon intensity value provided by Tomorrow co., which takes into account age and sex in calculating an average daily intake. The values are further adjusted depending on whether you eat beef and/or dairy and if the food is sustainably sourced. We then calculate the carbon intensity of alcoholic & non alcoholic beverages using the same method as detailed in the purchases category, and add that to get the final score.
  • Waste
    We start with the Australian household food & plastic waste averages, add in any disposables from the purchases category (e.g. paper towels, toilet paper etc) and then calculate the carbon intensity using the figures provided by the Tomorrow co. products database. We use adjusted life cycle stats for each waste material type, including average recycling rates. Your final score is then offset by the percentage of your food that is unpackaged & whether you compost your food waste.
  • Water
    The Bureau Of Meteorology estimates the carbon footprint of supplying Australian homes with water in each major district in the urban national report for water utilities. We take the mean of all major districts in each state to get a state average. This does not include the intensity of heating the water, so we have subtracted the total intensity of water heating (gas or electric) from the energy category and added it here for a more accurate look. We then distribute the score using yourhome.gov estimates to determine what percentage can be attributed to outdoor use, showers, toilet, laundry etc.
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