Calculation of footprint for goods and services

Calculate a personal footprint for goods and services consumption, from shopping and maintenance habits. This can be used to nudge people towards more sustainable consumption practices.

Inputs

This endpoint receives as optional input:

• a data source to base calculations on
• a list of consumption habits and household info
  • Number of household members
  • Monthly household income after tax
  • How much do you donate to charities? (Average per month)
  • How often do you choose quality products?
  • How often do you repair broken items?
  • How often do you choose ethical and environmental alternatives?
  • Do you choose services over products?
  • Do you recycle your waste?
• the date for which the footprint should be computed

The more questions a user answers the better we understand the user’s behaviour, giving a more accurate footprint estimation. Missing values are defaulted. If no input date is given, the current date is used as default. If no habits or household info are provided the calculation will assume default answers, i.e. that the user’s consumption habits are similar to an average person from the data source you have specified. This can be used to compare a person's goods and services footprint to the average person in a country.

Outputs

This endpoint returns a breakdown of an annual footprint from goods and services consumption in kilos of CO2e, with absolute and percentage values. 

The goods and services footprint is grouped based on the functionality of the purchase: “Household and maintenance, services, furniture and equipment, clothes and shoes, personal services, personal purchases” etc. 

If you have not submitted optional information, the footprint of an average person for the chosen data source will be returned.

Calculations

Income and expenditures

The consumption module calculates the climate emissions produced by goods and services unrelated to food, energy and transport. We calculate the average household’s consumption based on the household’s income, the idea being that the more you earn, the more income you have available to spend on goods and services. Again, this number changes based on the composition of your household. For instance, if there are three children in your household, the money it takes to feed them will mean that less money is allocated to consumption.

We use Statistics Norway’s Survey of Consumer Expenditure and the UK’s Office for National Statistics Family Spending Report to determine the average proportion that a household spends in 46 different consumption categories (based on COICOP). These categories include everything from hospital expenses to sporting equipment, and like the total consumption footprint, these vary based on the composition of your household. If you have no kids, you’re unlikely to spend money on primary school fees, so that gets allocated elsewhere.

The spending amounts are calibrated to the household income, and money spent on energy, transport and food are removed as these categories are considered from a bottom-up perspective. Tax has been removed from the income based on general tax tables, as emissions from tax money are covered by the public emissions. Any donations you make during the year are also removed from your consumption footprint. It’s true that those donations might be used for emissions-intensive activities elsewhere, however those emissions are allocated to the organisation or individual you’re donating to.

We make the assumption that all money you earn is spent in some way. You might put a lot into savings, but our calculator assumes that money will still be spent somewhere down the line on housing, tuition fees, or a different long-term savings goal. We’re currently working on improving our model for calculating the footprint of long term investments like housing.

The date also influences the calculations. We account for inflationary effects, temporal effects (higher energy prices in winter),  and their impact on your footprint. For example, as manufacturers decarbonize their supply chains, the emissions intensity of their products will decrease. Hence, if you buy the same product five years from now, the footprint of your purchase will be lower in the future.

Input-Out Calculations

We mentioned earlier in this document that household consumption is calculated using a top-down approach, as opposed to the bottom-up approach which is used for food, energy and transport. The top-down approach we use is better known as Input-Output modelling. You can read more details about how these calculations are made in Steen-Olsen et al. (2016). We use separate input-output databases for Norway and the UK. The information regarding the databases and the modelling choices used can be found in the intro to calculator methodology.

This approach doesn’t add up all your spending and calculate your climate emissions based on the combined emissions of that spending. Instead it takes the total emissions associated with each activity in the economy, and then decides what your share of those emissions is based on your income. For example, in Norway the average emissions for clothing are 44g CO2e per NOK spent, so your emissions for clothing are multiplied by the amount your household would normally spend on clothing. The sources for obtaining the average spending patterns are highlighted above.

On top of these consumption calculations, there are several personal habits which can affect the footprint of the user.

Quality and repair consumer

The main assumption here is that by purchasing a higher quality product, the user replaces the need to buy a similar product in a relevant time frame. Higher quality products last longer, so the CO2 multipliers are changed accordingly to reflect that. As an example, if you use an object 20% longer than its expected lifetime, you save climate change emissions equal to 20% of production emissions of that object. Analogous to higher quality purchases, we assume that repairing goods gives them a longer life span, thereby reducing the CO2  multiplier associated with goods spending by up to 20%.

Ethical consumer

For this habit it is assumed that the user tends to spend more money on ethical and environmentally friendly purchases. As environmentally friendly purchases are more expensive compared to their counterparts, less money is available to spend on goods & services, thereby reducing the footprint. Additionally, the CO2 multipliers for goods and services are modified to reflect environmentally friendly choices.

Service consumer

For this habit, it is assumed that extra money is spent on services and therefore, less money is available to spend on goods. If more money is spent on services, such as renting a movie online or using a subscription service as opposed to buying DVDs, the emissions related to manufacturing of goods decreases, and overall consumption emissions decrease.

Recycling

This habit gives insight on how much a consumer recycles. We have calculated the maximum amount possible to save by optimal recycling (approximately 100 kg/year), and found the percentage of the average footprint. Then used this to create an across the board value that modifies the CO2 multiplier in all goods and services categories based on the input for this habit.