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Overview of Ducky Challenge activity calculations

Learn how Ducky's climate activities are calculated, see source documents and research.

As a main rule the CO2e savings in a Ducky challenge are calculated by comparing a given activity with an average person’s behavior. Since the CO2e savings in the activities are compared to the average, everyone involved saves the same amount of CO2e for a given behavior, regardless of their inputs in the initial survey. 

The Ducky calculator is an aggregate of household- and habit data (how much people eat, what product groups they buy, etc) with calculations on the CO2e emissions associated with a given activity (kilometers driven, a certain food group eaten etc). Some calculations also require assumptions when all data is not available. For example, we know that on average 10% of purchased food is wasted, but we don’t know exactly how much someone who throws away very little food is actually throwing away. We know it is virtually impossible to waste no food, so we assume that someone who wastes very little only wastes 3% of the food they purchase. These assumptions are stated as plainly as possible in the following activity documentation.

Examples are included for each activity, based on the Norwegian case.

Food activities

As an example, the average diet of a Norwegian citizen consists of 2700 kcal per day, whereoff 880 kcal from grains, 620 kcal from fruits and vegetables, 296 from meat, 122 from fish, 614 from eggs and dairy products, and 210 from beverages. These numbers are based on Statistics Norway’s 2012 survey of consumer expenditure, slated to be updated in 2022. An additional 10% of calories are assumed to be wasted (thrown away). 

These numbers will vary from country to country, as will the CO2e saving associated with various activities.

I wasted no food today

Explanation: The calculator compares the CO2e footprint of someone with an average diet and waste pattern, to someone who eats an average diet but wastes much less than the average person. Research shows that an average person wastes about 10% of their food. Since it is virtually impossible to waste nothing, the Ducky calculator assumes that a person who actively tries to reduce waste may reduce this number to 3%. The difference in footprint between these behaviors gives the CO2 savings.

Example: The average Norwegian citizen’s CO2e footprint associated with food is 1520 kgCO2e/year. A typical waste scenario is 10% or 152 kgCO2e/year; a person who wastes very little only waste 3% or 45.6 kgCO2e/year. By subtracting these two values and dividing by 365, we get an average daily savings of 0.29 kgCO2e/day.

I ate vegetarian today

Explanation: The calculator compares the CO2 footprint of someone with an average diet, to someone who eats no meat. The daily calories associated with meat and fish consumption are reallocated equally between sugar and sweets, potatoes, vegetables, fruit and berries. The calculator therefore assumes that the same amount of calories are consumed regardless of diet. Since the amount of CO2 per calorie associated with these plant-based food categories is much lower than the CO2 per calorie meat and fish, the CO2 footprint of a vegetarian is lower than the average diet. 

Example: The average Norwegian citizen’s CO2e footprint associated with food is 1520 kgCO2e/year. By reallocating the calories typically consumed in the meat and fish categories to plant-based foods, and using appropriate CO2e multipliers to determine the new footprint, we find that a typical vegetarian’s footprint is 1135 kgCO2e/year. By subtracting these two numbers and dividing by 365, we get an average daily savings for 1.05 kgCO2e/day.

I ate fish instead of meat today

Explanation: According to our calculations, a flexitarian (someone who eats fish or meat once per week) and a pescetarian have approximately the same CO2e footprint, since the footprint of fish (per calorie) is similar to vegetables. To simplify the calculation, we have therefore calculated this indicator by comparing the CO2e footprint of someone with an average diet with someone who has a flexitarian eating pattern. The calories associated with meat and fish consumption are reallocated equally between sugar and sweets, potatoes, vegetables, fruit and berries. The difference in CO2 footprint between these two diets gives the savings associated with this activity.

Example: Whereas an average Norwegian consumes a bit more than 200 grams per day of fish and/or meat, a flexitarian would consume on average around 30g per day. The average Norwegian citizen’s CO2e footprint associated with food is 1520 kgCO2e/year. By reallocating the 86% calories typically consumed in the meat and fish categories to plant-based foods, and using appropriate CO2e multipliers to determine the new footprint, we find that a typical flexetarian’s footprint is 1189 kgCO2e/year. By subtracting these two numbers and dividing by 365, we get an average daily savings for 0.91 kgCO2e/day.

I ate less dairy today

Explanation: The calculator compares the CO2e footprint of an average person with the footprint of a person who eats half of the average amount of dairy. Note that our data set is currently grouped such that eggs, margarine and oils are included in the dairy portion of the calculator. The 50% of the calories associated with dairy for an average person are reallocated equally between bread, grain products, potatoes, vegetables, fruits and berries, and juice and mash, and the difference in CO2 footprint between these two diets gives the savings associated with this activity.

Example: The average Norwegian citizen’s CO2e footprint associated with food is 1520 kgCO2e/year, where 27% is from dairy products. If the consumption of dairy is halved over the course of one year, and the calories reallocated to plant-based foods, the yearly food footprint decreases to 1346 kgCO2e/year. Subtracting these two footprints and dividing by 365 days gives an average daily savings of 0.48 kgCO2e/day.

Transport activities

I walked or biked to work/school today

Daily saving (Norway): 4.43 kgCO2e

Explanation: The calculator finds the daily emissions associated with the average commute pattern. This is the daily savings, since walking or biking causes no CO2e emissions.  The savings for this activity does not take into account the actual distance you travel to work, only the average distance for the general population. The savings may therefore be unreasonably large if the individual lives close to work/school, or unreasonably small if the person lives farther than average away.

Example: The average Norwegian commuter travels 10km each way to work or school, drives a car with an internal combustion engine 4 days a week and takes public transport on the 5th. The average daily emissions are therefore ⅘ fossil-fuel commute and ⅕ public transport commute. The CO2e footprint of this commute pattern is 1062 kgCO2e/year. Assuming 48 work weeks per year, we find an average daily footprint of 4.43 kgCO2e, which is the daily savings if walking or biking are used as a commute transport.

I took public transport to work/school today

Explanation: The calculator finds the daily emissions associated with the average commute pattern, and compares this value to the average emissions associated with taking public transport the same distance 5 days a week. The difference between the two CO2e footprints gives the amount of CO2e saved for this activity. The savings for this activity does not take into account the actual distance you travel to work, only the average distance for the general population. The savings may therefore be unreasonably large if the individual lives close to work/school, or unreasonably small if the person lives farther than average away.

Example: The average Norwegian commuter travels 10km each way to work or school, drives a car with an internal combustion engine 4 days a week and takes public transport on the 5th, giving a CO2e footprint of 1062 kgCO2e/year. If public transport were used 5 days per week for the same commute distance, the footprint would be reduced to 374 kgCO2e/year. By subtracting these numbers and dividing by 240 work days per year, we find a daily savings of 2.87 kgCO2e.

I walked or biked to a leisure activity today

Explanation: Leisure transport includes all weekly non-work related travel, such as shopping, going to cafés or the movies, or engaging in sports.The calculator finds the default emissions associated with an average pattern of travel leisure activities , and divides by 365 to get the daily emissions. Since walking or biking causes no CO2 emissions, this amount is the daily savings.

Example:  The average Norwegian travels to leisure activities using public transport for 20 km/week, carpooling for 20 km/week and a fossil-fueled car for 100 km/week, which yields a yearly footprint of 1524 kgCO2e, corresponding to a potential daily savings of 4.18 kgCO2e if biking or walking replaces motorized vehicles.

I took public transport to a leisure activity today

Explanation: Leisure transport includes all non-work related travel, such as shopping, going to cafés or the movies, or engaging in sports. The calculator finds the default emissions associated with an average pattern of weekly travel leisure activities. We then assume that the kilometers typically driven in a fossil fuel car are replaced by public transport, and the corresponding CO2 footprints are calculated. The daily savings is found by subtracting these two footprints and dividing by 365 days.

Example: The average Norwegian travels to leisure activities using public transport for 20 km/week, carpooling for 20 km/week and a fossil-fueled car for 100 km/week, which yields a yearly footprint of 1524 kgCO2e. If the 100 km/week in a fossil-fueled car are replaced by public transport, the yearly footprint becomes 594 kgCO2e. By subtracting these two numbers and dividing by 365 days, we find a potential daily savings of 2.55 kgCO2e.

I took an electric car to work today

Explanation: The calculator finds the average daily emissions associated with a typical commuter pattern, and compares this value to the average emissions associated with driving an electric car the same distance 5 days per week. 

Example: The average Norwegian commuter travels 10 km each way to work or school, drives a car with an internal combustion engine 4 days a week and takes public transport on the 5th, giving a footprint of 1062 kgCO2e/year. If all of these kilometers were driven in an electrical car, this footprint would be 389 kgCO2e/year. By subtracting these numbers and dividing by 240 working days in a year, we find a potential daily savings of 2.8 kgCO2e. Note that in Norway, where buses are primarily fossil fueled and electric cars run on relatively clean energy, the CO2e intensity of driving an electric car per kilometer is similar to taking public transport. 

I took an electric car to a leisure activity today

Explanation: Leisure transport includes all weekly non-work related travel, such as shopping, going to cafés or the movies, or engaging in sports.The calculator finds the default emissions associated with an average pattern of travel leisure activities, then finds the emissions if all leisure travel is accomplished with an electric car. The daily difference between these emissions is the potential savings.

Example: The average Norwegian travels to leisure activities using public transport for 20 km/week, carpooling for 20 km/week and a fossil-fueled car for 100 km/week, which yields a yearly footprint of 1524 kgCO2e. If all 140 km/week of leisure travel is accomplished with an electric car, the yearly footprint could be reduced to 536 kgCO2e. The potential daily savings is therefore 2.71 kgCO2e.

Goods and Services

I researched an environmental profile today

Explanation: The default emissions throughout a year associated with an average spending pattern are found. Then the emissions associated with more environmentally-friendly purchases are calculated. This calculation is performed by assuming that a more environmentally-friendly pattern is associated with more expensive food, transport and vacation purchases, leaving less money for spending on consumer goods and services. Furthermore, the money spent on goods and services is assumed to be 10% less CO2e intensive than the average. 

The difference between default emissions and the emissions associated with environmentally-friendly spending are calculated, given the CO2e footprint reduction over the course of the year. 

We assume that you would develop the habit of spending more environmentally friendly if you research an environmental profile every third day during a challenge. This means that the savings is three days worth of daily emissions associated with the yearly spending pattern. Said in another way, we don’t know the exact amount of CO2e associated with a single environmentally-friendly purchase as this varies greatly, so that activity gives credit to the habit of environmentally-friendly purchasing.

Example: For the average Norwegian income (around 492 000 NOK/year before taxes), the average footprint associated with goods and services is 4656 kgCO2e/year. Green choices are expected to raise your spending in the transport, food and vacation categories by 6000 NOK/year, reducing the available money to spend on other goods. By further reducing the CO2e multipliers on all goods and services by 10%, we find the footprint of an ethical and environmentally-friendly consumer to be 4011 kgCO2e/year. The difference between the two footprints is divided by 365 then multiplied by three to denote a habit-forming activity, giving 5.3 kgCO2e saved per time this challenge is logged.

I recycled all possible waste today

Explanation: Using numbers from recycling companies, we examined both how much is recycle of different materials today and, we have estimated the maximum feasible savings if all recyclable waste was recycled during the course of a year. For paper and plastic recycling, we compare the footprint of recycling as opposed to burning, while for glass and metal we considered the footprint savings of recycling as opposed to making completely new materials. The maximum CO2e it is possible to save is converted to a percentage of the overall average footprint and calculated equivalently depending on income.

Example: Maximum recycling in Norway could save about 6% of the average footprint, corresponding to 0.48 kgCO2e/day.

I donated money to a good cause today

Explanation: The calculator first finds the daily goods and services emissions of the average consumer, whom we assume donates no money to charity. We then assume that a certain amount of money is contributed to charity, and this amount is subtracted from available income to spend on goods and services. Since the amount of money spent on each good and service is multiplied by a CO2/kr multiplier, this causes a decrease in total emissions. The difference between the yearly emissions is then divided by 365 days. If your donation is significantly larger or smaller than the assumed amount, the emissions estimation may be low or high respectively. 

Example: In Norway we assume a charitable consumer might donate 750 NOK/mth. This decrease in available spending money corresponds to a footprint reduction from 4656 to 4355 kgCO2e/year, translating to a potential savings of 0.82 kgCO2e per day.

I spent money on services today

Explanation: The calculator first finds the CO2 footprint of goods and services for the average consumer. It then calculates the goods and services footprint of a consumer who preferentially spends money on services rather than goods. The calculate functions with over 40 different goods and services categories, some of which are services and others goods. The amount of money spent in goods categories is reduced by 20%. The amount of money saved on goods is then reallocated to service categories proportionally to the fraction spent in this category by the average person. The difference between the emissions of the average consumer and one who preferentially buys services is then calculated, resulting in a yearly total. 

The yearly total is converted into a three-day value, since services (e.g. hair cut, theater tickets) are typically not a daily expense. With other words, the savings on this activity is three days worth of daily emissions associated with the yearly spending pattern.

Example: The average Norwegian reducing their spending on goods by 20% and increasing it accordingly in services reduces the yearly goods and services footprint from 4656 to 4296 kgCO2e/year. The three-day value of this is 2.95 kgCO2e, which is the potential savings achieved by logging this activity.

I repaired something today

Explanation: The calculator first finds the CO2 footprint of goods and services for the average consumer.  The goods and services footprint of a consumer who tends to repair goods is then calculated by assuming that money spent on goods is 20% less CO2 intensive than the average, since the goods will last for longer. The difference between these two emissions is calculated to give a yearly savings. The yearly savings is converted to a three-day value, since a repair is not an everyday activity and therefore the emissions savings should be proportionally larger.

Example: For the Norwegian consumer, a 20% reduction in the CO2e multipliers in goods categories causes a reduction of the yearly consumption footprint from 4656 to 4069 kgCO2e, corresponding to a three-day value of 4.82 kgCO2e. Which is the potential savings achieved by logging this activity.

Energy

I reduced the indoor heating today

Explanation: The calculator finds the energy reduction associated with decreasing the temperature in the average house by two degrees. Heating energy is converted to CO2e based on the energy mix for the country.

Example: The average Norwegian house is a two-person row house of 110 sqm, renovation in 1980’s. The default heating mode is “I don’t know” (which gives a mix of electricity and fossil sources), and 90% of the housing area is assumed to be heated 22°C. Assuming the Nordic electricity mix, we find a potential energy savings of 0.34 kgCO2e by reducing the temperature to 20 °C.

I reduced the indoor temperature overnight

Explanation: The calculator finds the energy reduction associated with decreasing the temperature in the average house by two degrees. Heating energy is converted to CO2e based on the energy mix for the country. We then assume that reducing the temperature overnight corresponds to 8 hours or ⅓ of the day, so the reduction is ⅓ of that of reducing the temperature all day.

Example: The average Norwegian house is a two-person row house of 110 sqm, renovation in 1980’s. The default heating mode is “I don’t know” (which gives a mix of electricity and fossil sources), and 90% of the housing area is assumed to be heated 22°C. Assuming the Nordic electricity mix, we find a potential energy savings of 0.11 kgCO2e by reducing the temperature to 20 °C for 8 hours.

I switched off unnecessary lights today

Explanation: We assume that about 70% of lights are typically on unnecessarily. The calculator therefore finds the difference between the lighting energy in an average household, and one with 70% less energy used on lighting. The energy savings are converted to CO2e savings. If you tend to leave more than 70% of lights on unnecessarily, the savings could be even larger. 

Example: In Norway, the average energy use associated with lighting is 525 kWh per person per year in a two-person household. Reducing this by 70% gives 376.5 kWh. The CO2e multiplier for the Nordic electricity mix is 0.128 kgCO2e/kWh, which gives 47 kgCO2e/year, or a potential energy savings of 0.13 kgCO2e/day. Note that these estimates assume that the average household has about 15% LED lights; if you have more LED lights, the savings could be less and vice versa.

I didn't wash clothes or ran a full load when washing today

Explanation: The calculator finds the average household footprint associated with average energy consumption for general electricity use, which is the total energy use minus the contributions to heating of water and household, and lighting. We assume the conscientious washer runs washing machines about half as often as someone who does not pay attention to this sort of thing, and that this also reduces the use of tumble drying (as fewer loads of clothes washing means fewer loads of clothes drying!). We calculate the amount of energy saved by washing dishes or clothes half as often as the average, and convert this to CO2e footprint savings.

Example: In Norway, the average energy use for running dishwashers and washing machines is 388 kWh per year, where about 60% is used to wash clothes. Given that this can be reduced by 50% by washing full loads, 116 kWh of electricity can potentially be saved per year. Additionally, tumble drying accounts for about 105 kWh per year, about half of which could be saved by decreasing wash frequency. Since the CO2e multiplier for the Nordic electricity mix is 0.128 kgCO2e/kWh, we find a potentially yearly savings of 21.6 kgCO2e per year or 0.0 kgCO2e per day.

I used a clothes horse today

Explanation: The calculator finds the average household footprint associated with average energy consumption for generally electricity use (excluding house heating, water heating, and lighting). Approximately 7% of this energy goes to tumble drying. We calculate the CO2e reduction if no electricity was used for tumble drying. 

Example: The average Norwegian uses about 105 kWh per year tumble drying. If tumble drying were eliminated, 13.4 kgCO2e could be saved yearly, corresponding to 0.04 kgCO2e per day.

I reduced the amount of dishes today

Explanation: We assume that a person who actively tries to reduce the amount of dishes creates 50% less dishes that the average person. By calculating the average energy spent on dishwashing, and converting it to kg of CO2, we can find the footprint savings of a person who reduces their dish washing by 50%.

Example: In Norway, this action corresponds to a potential savings of 0.04 kg CO2e

I unplugged all electrical devices today

Activity savings: 0.06 kg CO2e

Explanation: About 2.5% of electricity is used by electronics on standby. We assume that by unplugging unused devices, this can be reduced by 30% (since some appliances, like your refrigerator, always need to be plugged in!) By multiplying this through with the average yearly electricity consumption, and dividing by the number of household members and days in a year, we get the yearly energy savings associated with unplugging unnecessary electronic devices.

Example: In Norway, this action corresponds to a potential savings of 0.06 kgCO2e per day.

I haven't used any electronic devices tonight

Explanation: The calculator finds the average household footprint associated with average energy consumption for general electricity use, which is the total energy use minus the contributions to heating of water and household, and lighting. About 15% of this is spent powering gadgets. We assume that not using any electronic devices for an evening reduces this by 40%. We then calculate the amount of energy you save, and equate this to kg of CO2e.

Example: In Norway, this action corresponds to a potential savings of 0.05 kgCO2e per day.

I showered for 5 minutes or less today

Explanation:  The calculator compares the average shower length to the new shower length, and calculates the amount of hot water saved by decreasing your shower time. By multiplying by a heating factor, we get the total amount of energy saved, which can then be equated to CO2 footprint.

Example: In Norway, the average shower is 8 minutes long, so 3 minutes worth of hot water are saved by this action. A regular shower uses 9.5 liters of hot water per minute, which corresponds to a potential savings of 0.16 kgCO2e per day.

I had a body wash instead of a shower today

Explanation: We assume that a body wash only uses the equivalent of 1 min of hot water showering. Assuming that the average shower lasts for 8 minutes, you then save 7 minutes worth of hot water. A regular shower uses 9.5 liters of hot water per minute. By multiplying by a heating factor, we get the total amount of energy saved, which can then be equated to kilos of co2.

Example: In Norway, this action corresponds to a potential savings of 0.38 kg CO2e

I used less hot water from the tap today

Explanation: In addition to showering, the average person uses 10 liters of hot water per day for other purposes. We assume that by actively reducing the amount of water you use, you are able to decrease this to 3 liters, thereby saving 7 liters of hot water. By multiplying by a heating factor, we get the total amount of energy saved, which can then be equated to kilos of co2.

Example: In Norway, this action corresponds to a potential savings of 0.04 kg CO2e