Lumo homes carbon footprint test’s calculation criteria

Lumo homes' carbon footprint test has been published at lumo.fi/en/carbon-footprint-test

The carbon footprint test for Lumo homes is based on the Sitra's lifestyle test where the part 1 (Living) and part 2 (Transport and tourism) has been modified. The original calculation was changed to cover only the locations and housing types that are possible for Lumo homes. The modified version also takes into account the used heating systems in Lumo homes, and the carbon neutral real estate electricity used. The calculation was also expanded to cover the use of saunas and car sharing. In addition, the emission factors for the calculations were updated during the modification of the calculation.

The calculation is based on the calculation criteria made by Emma Hietaniemi from Sitra and Jari Kolehmainen, Viivi Toivio and Michael Lettenmeier from D-mat Oy (Calculation basis used in the lifestyle test, dated 19.3.2021), with updated parts 1 and 2 as mentioned above. In the calculation criteria introduced below, the assumptions and emission factors used in the calculations are described. The list of sources is also updated. Parts 3 and 4 remain same as in the original version of the calculation criteria.

Gaia Consulting / Jatta Aho, Magda Horváth, 25.4.2022

The climate impacts of living taken into account in the carbon footprint test include construction, heating of the apartments and the use of electricity. The questions in the test are in the order below.

City of residence

The respondents are asked in which part of Finland they live. This defines how much less/more heating energy is needed in comparison to the average consumption of heating energy in Southern Finland. The energy needed for heating increases 10% in the middle parts of Finland and 25% in the Northern Finland (Motiva 2017a).

Building of a block of flats or a townhouse

The environmental impacts of building are taken into account by using an emission factor calculated per living area and the number of years the building has been in use (Saari et al. 2001: a block of flats equals 8.0 and townhouse equals 6.9 kg CO₂e/y/htm²). The factor takes into account land-use change, production of the building materials, construction, maintenance and demolition of the building. The assumed total lifespan of the building is 50 years.

The building year’s effect on the need of heating

For different house types built in different years, separate heating factors per floor area has been calculated from the averages of Lumo homes’ heating consumption data. The heating method of the home is not asked from the respondents and the emissions of heating are calculated as a weighted average based on the emissions of a similar (house type and building year) Lumo home.

The average Finnish district heating emission factor is 141 g CO2/kWh based on the carbon dioxide emission statistics collected by Statistics Finland (Tilastokeskus 2019). To balance seasonal variation, the figure used is the 5-year moving average reported by Statistics Finland, and in addition, the benefit sharing method is applied to the factor. The benefit sharing method refers to the sharing of specific emissions between electricity and heat when estimated with alternative production methods. In addition, the emissions of the beginning of the district heat’s lifecycle are accounted for (around 33 g CO2ekv/kWh) (Defra 2021).

In the emission factor of green district heating the same phases of the lifecycle are included and it is similarly around 33 g CO2ekv/kWh (Defra 2021). In the use of geothermal heating the green real estate electricity is used for the calculation.

Electricity consumption

The default value for electricity consumption (excluding electricity used for heating) is based on a survey on households' electricity consumption conducted in 2011 (Adato Energia 2013). The default values are calculated as follows, when X = (number of people in the family - 1):

Block of flats = 1400 + (X * 500)
Townhouse = 2600 + (X * 700)

The greenhouse gas emissions of electricity production include the direct emissions of electricity production i.e., the emissions caused by burning of fuels and the fuel production chain. The Finnish average emission factor of electricity production is 155 g CO2ekv/kWh including both direct emission and the production chain of the fuel (Tilastokeskus 2019, Defra 2021). The emission factor for green electricity has the same boundary as the conventional electricity emission factor and is 39 g CO2ekv/kWh (Defra 2021). Green electricity has also been taken into account in rail transport (see the transport section).

Room temperature

The effect of room temperature is also taken into account in the need of heating energy. A two-degree drop/rise in the room temperature may reduce/increase the need for heating energy by 10% (Motiva 2017b).

Shower and sauna

The time spent in a shower affects water consumption and therefore also the amount of heating energy used for heating the water. Heating one liter of water to the temperature of 40 degrees Celsius requires 0.04 kWh of energy (D-mat 2019). In addition, the energy use of sauna bathing is included in the calculations. One sauna bathing session is assumed to last for one hour and the heating of the electric sauna takes half an hour. The assumption is that the stove is a 15-kW stove and therefore the electricity consumption is 15 kWh/hour. If the tenant uses the common sauna of the housing cooperative, the sauna is heated with the green real estate electricity that is used in all Lumo buildings. If the tenant uses their own sauna, the electricity emission factor is chosen according to their answer of the electricity used. The assumption is that the standard electricity consumption includes going to sauna once a week but if the tenant answers that they use sauna 3 or 7 times per week the emissions increase accordingly.

My Lumo service

If the test is done by logging in to the My Lumo service, some of the tenant’s background information can be used for the test. This data is for example type of building, floor area of the apartment, heating method and the year of construction. Based on this information the tenant doesn’t have to answer all the questions that are in the Lumo.fi site. The calculation criteria are same in both sites.

The average estimates on the use of different means of transport are based on the National Travel Survey (Liikennevirasto 2018) statistics.  

The carbon footprint of driving is calculated based on the annual number of kilometers driven and the average number of people driving a car and the use of an own and car sharing car are separated. At the moment no statistical data of the kilometer-based climate emission savings from using car sharing are available. Therefore, in the calculation there is no difference between own cars and car sharing. For driving, the climate emissions consist of the fuel production and consumption, manufacturing of the car and the emissions from building the road infrastructure. The generated emissions are divided between the number of people typically driving a car. The emission factors for personal cars using different fuels are based on the emission factors per passenger kilometer reported by Defra (Defra 2021).

The emissions generated by the manufacturing of different car types are based on global average rates (Wilson 2013). Approximately 10% (20 g CO₂/vehicle km) of the overall emissions from driving are allocated to road infrastructure (Hill et al. 2012).

Public transport includes travel by bus, train, tram and metro. The relative shares of the different means of public transport are based on the National Travel Survey (Liikennevirasto 2018) statistics. The shares were used as a basis for calculating a weighted average emission factor for public transport. The emission factors of different means of transport are based on the emission factors reported by Defra (Defra 2021). Regarding rail transport, the use of green electricity by VR and Helsinki City Transport were taken into account.

The emission factor per hour for air travel is based on Defra’s average greenhouse gas emissions for international air flights per travelled kilometer including the radiative forcing and the production of the fuel (Defra 2021). The emissions of individual flights depend on such factors as the air fleet, aircraft occupancy rate, allocation of emissions between passengers and cargo, as well as taking into account the impact of clouds in the higher atmosphere.

In addition to direct CO₂ emissions, air traffic increases atmospheric radiative forcing, as a result of fine particles released high in the atmosphere and changes in cloud cover, for example. The average airspeed of air traffic is based on the average flight speeds of different types of aircraft reported by Finnair (Finnair 2019).

The average lengths of passenger shipping are based on the Statistics Finland material (Tilastokeskus 2016b; 2017a) on the travel habits of Finns. The average emission factors for maritime passenger transport were calculated on the basis of the lengths of Helsinki-Tallinn-Helsinki and Helsinki-Stockholm-Helsinki routes and Defra’s unit emission factors of average passenger ships (Defra 2021).

The carbon footprint of the person taking the carbon footprint test is affected by the amount of food he or she eats and the amount of waste this generates as well as the relative amounts of different ingredients used. It is assumed that a respondent who eats less/more compared to other people at a mealtime, eats 15% smaller/larger portions per meal.   

In the carbon footprint test, the respondent's diet is further calculated on the basis of the ingredients he or she consumes at mealtimes. The consumption of various products either reduces or increases the footprint, depending on whether the respondent eats less or more of such products compared to the average consumption habits in Finland. The reducing/increasing effect of the choices is deducted from/added to the carbon footprint of an average Finn, which is approximately 1.6 tons a year (Seppälä et al.; Lettenmeier et al. 2018).

The ingredients with significant climate impact have been classified into various categories: beef and hard cheese / pork, chicken, fish, cottage cheese, fresh cheese and other soft cheeses and eggs / milk and dairy products / drinks. An average portion size was calculated for each category and a portion- specific weighted emission factor was calculated based on the percentage of the various ingredients in the portion. The portion sizes of the various ingredients are based on the reported annual consumption of food commodities per capita (Luonnonvarakeskus 2017) and the food measures defined by the National Public Health Institute (Sääksjärvi & Reinivuo 2004). The sources used for emission factors included the climate impacts of products defined in Kausiruokaa (Seasonal food) publication by Kaskinen et al. 2011 and the ecoinvent database (Wernet et al. 2016). For example, the Climate Guide (Ilmasto-opas.fi) gives several estimates of the greenhouse gas emissions of foods.

Beef and hard cheese were classified under the same category due to having higher emission factors than other foods (the Climate Guide: beef 14–42 kg CO₂e per kg, Kaskinen et al.’s estimate for European meat: 19 kg CO₂e per kg; hard cheese, Voutilainen et al. 2003: 13 kg CO₂e per kg). For cheese, there were both international (e.g. the ecoinvent database) and Finnish (e.g. Voutilainen et al. 2003, Aalto 2018) estimates available; the carbon footprint of Finnish cheeses was typically estimated to be lower. This is explained by the differences between the emission factors of milk produced in different countries (e.g. Pulkkinen 2018). In the carbon footprint test, it was decided that more weight is placed on emission factors calculated according to the Finnish approach. When it comes to the carbon footprint, cottage cheese, fresh cheese and other soft cheeses differ clearly from hard cheeses, which require more milk and a longer maturation period. For this reason, an emission factor of 6.5 kg CO₂e per kg has been assigned to soft cheeses, placing them in the same category as pork, chicken, fish and eggs in the carbon footprint test (e.g. the Climate Guide).

Cottage cheese, fresh cheese and other soft cheeses, pork, chicken, fish and eggs were classified into a single category. The emission factor of pork is slightly higher than that of other foods in the category but, on the other hand, significantly lower than the emission factor of beef. The emission factors used are the following: 5.6 kg CO₂e per kg for pork, 3.6 kg CO₂e per kg for chicken, 3.0 kg CO₂e per kg for fish and 2.7 kg CO₂e per kg for eggs (Kaskinen et al. 2011). The calculator does not make a difference regarding whether the meat consumed is game since game accounts for only approximately 2 per cent of the meat consumption of an average Finn. The estimated emission factor for domestic elk meat, for example, is 1.6 kg CO₂e per kg (Kaskinen et al. 2011), for which reason the carbon footprint of a person consuming game as the primary meat product can be assumed to be lower than that of a person consuming meat of animals bred for the production of food. Further information on the climate impact of game and other meat products in the WWF Meat Guide (in Finnish at wwf.fi/lihaopas).

Milk and dairy products were highlighted as a third category, since their high consumption has an effect on the carbon footprint. Finns consume annually approximately 125 kg of milk and approximately 40 kg of dairy products (excluding cheese) per person. In the carbon footprint test, the emission factor used for milk is 1.4 kg CO₂e/kg (Kaskinen et al. 2011: low-fat milk from Finland).

For drinks a portion-specific environmental impact was calculated, being approximately 0.3 kg CO₂e/portion (range 150–400 g/portion). The emission factors for different drinks are based on the sources Kaskinen et al. (2011), Wernet et al. (2016) and Berners-Lee (2010).

As concerns meals eaten outside the home, the energy consumption used for providing the service, or preparing the food (2 kWh/time eating out), was taken into account.

Finnish people throw away approximately 23 kg of edible food a year (Saarinen et al. 2011), which increases the carbon footprint. The emission factor for food waste was calculated based on the biowaste of an average Finnish person eating a mixed diet (2.55 kg CO₂e/kg biowaste).

Living, mobility and food are the most significant sub-sectors in the carbon footprint of an average consumer. It would require a number of questions to make a comprehensive estimate and analysis of the climate emissions of other sectors of personal consumption. In such a case, the effort it would require for a respondent to complete this section would no longer be in proportion to the significance of this sub-sector. However, in the carbon footprint test we wanted to highlight a few important matters, acknowledging that other choices (such as services and interests) have an impact as well. In this calculator, the sub-sectors included contain pets, summer cottages and consumption of goods.

The question concerning shopping habits includes goods, household articles, clothes and footwear. The question does not cover environmental impacts related to services, only tangible products. On average, the combined climate emissions of furnishings and home care products, clothes and footwear, goods related to spare time activities and hobbies, audiovisual devices, as well as books, magazines, newspapers and paper products amount to approximately 600 kg/person/year (Seppälä et al. 2009). The estimates of minimum and maximum values of goods consumed, on the other hand, are based on a survey by Kotakorpi et al. (2008). The carbon footprint of a person buying recycled goods is estimated to be 50% smaller than that of an average consumer, because buying recycled products, does not generate the climate emissions caused by the manufacturing of new goods and clothes.

Pets bring joy to people's lives and are often treated as members of the family. However, pets also consume natural resources in the form of food and different services and products. Still, the question concerning pets is difficult, because pets can be of very different sizes. The estimate about the average monetary value of the products and services Finnish people use for their pets is based on the PetNets survey (2015). On the other hand, the estimates on the quantitative content of products and services are based on the price comparisons of various service providers and companies. The estimates produced by Hirvilammi et al. (2014) on the air consumption of different services were used as the source for the climate emissions of services. Air consumption describes the amount of air changed chemically or physically or used for combustion, or in practice the amount of oxygen, used for producing a service. The air consumption is often directly proportional to CO₂ emissions, because burnt oxygen generates CO₂. The climate emissions of food consumed by pets were estimated by comparing the nutritional values of dog and cat foods and using the emission factors of the ecoinvent database.

There are almost 500,000 summer cottages in Finland. The average living area of a summer cottage is approximately 50 m², but there is a lot of variation in how the cottages are equipped (FCG 2016). In the question about summer cottages, the assumption is that the summer cottage is modestly equipped. The average electricity consumption during summer season and/or winter season was also taken into account (Piiroinen 2009). It is assumed that basic heating is maintained in a cottage used year-round even when it is not in active use. The earlier answer given by the respondent on whether he or she uses ordinary or ecological electricity was taken into account when calculating electricity consumption. In addition to electricity consumption, the carbon footprint test accounts for the climate impacts of the consumption of raw materials needed for building the cottage, land use and maintenance of the cottage. The emission factor used is based on the calculation made by Salo et al. (2008) on the day-specific air consumption caused by the use of a cottage (modest free‐time residence 27 kg/day). The estimates of the average usage of cottages in summer and winter (days/year) are based on the statistics of the Free‐Time Residence Barometer (FCG 2016). The climate emissions generated by the use of a cottage are divided between people using a cottage on a regular basis.

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