The methods and data behind the Carbon Donut

Spark’s Carbon Donut was developed to help you pinpoint where your carbon emissions come from, and to give you a tool that will help you see which decisions affect your emissions the most. The Carbon Donut only includes data on emissions that you can actually control. Hence, it differs from your carbon footprint, which is calculated by dividing the overall greenhouse gas emissions of a nation by the number of citizens.

There are two versions of the Carbon Donut — the simple one, and the more detailed one for those who want to dive a little deeper into the carbon jungle. The simple version is great to play around with, and gives you instant feedback on what a certain change would mean for your climate impact. The detailed version requires a little more input from you, and can therefore also give you a more accurate result. Your Carbon Donut is still only a fairly rough estimate of your climate impact, since we at Spark wanted to keep things simple for you.

All emissions in the Carbon Donut are calculated per person. This means that if you live with a flatmate, we divide the emissions caused by heating and powering your home between you and your flatmate, resulting in half the emissions compared to if you were to be living alone. The same goes for car driving: the more people in the car, the lower the emissions!

All emissions are calculated for an entire year. So far, the Carbon Donut only includes Finnish data, but we are working on adding data for other countries as well!

If you want to know what values and assumptions the Carbon Donut uses, take a look at the descriptions for each category below:


Emissions from heating are calculated based on two input values:

  1. The size of your home and the number of people in the household, to calculate the heating needed per person.
  2. The type of fuel that is used for heating, to calculate the emissions per unit of heat.

The need for heating is partly based on the need for space heating, which is not dependent on the number of people living in the household, and partly based on the need for warm water (for things like showering, washing dishes and clothes, etc.), which is dependent on the number of people.

The amount of heating needed per square meter of living space is typically dependent on when the house was built, but the Carbon Donut utilises an average number of 150 kWh/m2 (VTT, 2018). It then adds the heat required for hot water, which is estimated to be 1000 kWh per person and year (Vattenfall, n.d.).  

The amount of heat you use is multiplied by an emission coefficient, which depends on which fuel is used, to determine the emissions that arise from it. The coefficients and information about the data are listed in the table below.

Table describing the carbon emissions from different heat sources.

*Life cycle emissions estimated and added to make these comparable with emissions from wood pellets & heat pump heating.

In reality, emissions from district heating varies from city to city, but at the moment the Carbon Donut doesn’t account for that and uses an average instead.


In the case of electricity, emissions are calculated in much the same way as for heat:

  1. The amount of electricity consumed is determined based on the size of your home and the number of people living in it. The Carbon Donut also takes into account whether there is floor heating, and if there is a sauna, how frequently it is used.
  2. The amount of emissions caused by electricity consumption is calculated by multiplying the kilowatt hours used by an emission coefficient, which is dependent on the type of electricity used.

Electricity consumption and emissions are calculated based on the formulas and data in the table below:

Table describing how electricity consumption has been calculated as well as the greenhouse gas emissions from different types of electricity sources.

Emissions from electricity are either zero (for certified renewable power) or 249 g CO2/kWh. The latter corresponds to the average emissions for all electricity consumed in Finland, excluding certified green electricity. In other words, it is the average emission coefficient for electricity from fossil fuels, nuclear power, and non-certified renewable electricity, either generated in Finland or imported. (Energy Authority, 2020.)


The greenhouse gas emissions for different vehicle types have been obtained from the LIPASTO unit emissions database (VTT, 2017). LIPASTO reports so called unit emissions, measured in grams per kilometer, or grams per passenger kilometer for public transport. Electric vehicles are an exception, in which case the electricity consumption per kilometer is presented instead. The Carbon Donut then calculates the emissions by multiplying the electricity consumption with the emission coefficient for the Finnish electricity mix (the average emission coefficient for all electricity sources consumed in Finland), which is 141 g CO2/kWh (Motiva, 2020).

Spark’s Carbon Donut does not take life cycle emissions into account in its transport calculations. The only emissions that are included are the ones related to fuel consumption (or in the case of electric vehicles, electricity production). Emissions from manufacturing vehicles or batteries for vehicles have been omitted.


Emissions from flying has also been obtained from the LIPASTO database. Since flight emissions are highly dependent on the type of aircraft and the aircraft depends on the distance travelled, LIPASTO has split its data into emissions for short national flights, long national flights, short European flights, long European flights and intercontinental flights. The data is given as unit emissions in grams per passenger kilometer. The Carbon Donut then transforms this data into grams per passenger hour using Finnair’s flight schedules for corresponding travel distances. It then uses an average for all distances to calculate the emissions based on the input hours.

According to the LIPASTO data, short European flights have a higher unit emission than longer distances or long national flights. This means that if you do several short trips within Europe for a total of 16 hours, your emissions are higher compared to if you would do one longer trip to Northern America, amounting to 16 hours. However, your Carbon Donut looks exactly the same in both cases, simply to keep the test as easy to use as possible.

Note that the LIPASTO data only includes direct emissions from burning the fuel. It does not take into account the radiative forcing index (RFI), which describes the effect of for example changes in ozone concentration and cloud formation. According to Finnair, newer publications typically reports an RFI below 2 (Finnair, 2018).


Carbon emissions from different food types have been retrieved from Mat-klimat-listan (Röös, E., 2012). The values that are reported there are average values based on a literature review, and contain all emissions related to production, processing and packaging. Transport from abroad has been included for such food types where it has a significant impact.

The total emissions for an average Finnish diet (called “carnivore” by the Carbon Donut) have been calculated by multiplying these values with the average consumption data, obtained from Luonnonvarakeskus (2017). Total emissions for the omnivore diet has been calculated by replacing 50% of the meat and fish with an amount of beans adding up to the same protein intake, and by increasing cheese consumption by 15%, and nut consumption by 100%. For the pescetarian, meat has been replaced by beans, fish consumption has been increased by 20%, cheese consumption by 30%, and nut consumption by 150%.

In the vegetarian diet, both meat and fish have been replaced with beans. Cheese consumption has been increased by 30%, and nut consumption by 150%. For the vegan, meat, fish, eggs and dairy have been replaced by beans. Nut consumption has been increased by 300%, and rice by 100%. Consumption of fruits and vegetables have been increased for all types of diets compared to the average one. The amount of consumed vegetable oils has been increased for the pescetarian, the vegetarian and the vegan diet.


Emission data for consumption has been obtained from Ilmastodieetti (2017), which in turn uses ENVIMAT model values from 2013. The data is given as kg CO2-eq per € for different categories, including clothes, electronics, hobbies etc. For average shopping, the Carbon Donut uses consumption data for the average Finn, as reported by Ilmastodieetti.

Table describing average yearly spending and the greenhouse gas emissions of different consumption categories.

The data has been split up into four different categories; clothes & shoes, electronics, things for the home, and hobbies & services. For the first three categories, you can define both how much you shop in each category, and how often you shop it second hand. The shopping amount is described on a scale from 1 (“I rarely buy anything”), which is defined as 10% of the average Finn, to 5 (“I love shopping”), which is defined as 200% of the average Finn. 3 (“Pretty average”) corresponds to the Finnish average spending, and the scale towards each end is linear. For the question whether you shop second hand, the Carbon Donut accepts values between 1 (“Nope”), for which the shopping amount remains the same, to 5 (“Always”), for which the shopping amount decreases by 90%. 3 (“Sometimes”) means the shopping amount is reduced by 40%. Again, the scale from the middle towards each end is linear.

For the fourth category, hobbies & services, the calculator only requests input on the amount consumed. Again, the scale goes from 1 to 5, 1 (“Very seldom”) representing 30% of the Finnish average, and 5 (“Very often”) representing 150% of the Finnish average. 3 (“Pretty average”) corresponds to the Finnish average, and the scale towards each end is linear.

In addition to these four categories, the Carbon Donut assumes a basic consumption constant that is independent on the user input. It includes for example internet connection, phone subscription, newspapers etc., and adds up to 7.6% of the consumption emissions for the average Finn.

Do you have any questions about the Carbon Donut or its data? Don’t hesitate to contact us!


Energy Authority, 2020. Vuoden 2019 jäännösjakauma julkaistu.

Finnair, 2018. Finnair Emissions Calculator.

Ilmastodieetti, 2017. Ilmastodieetti – mihin sen antamat ilmastopainot perustuvat?

Luonnonvarakeskus, 2017. Tilastotietokanta: Elintarvikkeiden kulutus henkeä kohti (kg/vuosi).

Motiva, 2020. CO2-päästökertoimet.

Röös, E., 2012. Mat-klimat listan.

Statistics Finland, 2020. Fuel classification.

Vattenfall, n.d. Energianeuvonta.

VTT, 2017. LIPASTO unit emissions.

VTT, 2018. Laskennallinen energiankulutus Helsingin rakennuskannassa ikäryhmittäin.