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updated documentation and sources, added cross-references
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Expand Up @@ -5,43 +5,50 @@ The *co2calculator* can compute emissions caused by mobility, heating and electr
## 1 General information
### What are CO2 e-emissions?

Anthropogenic climate change is caused by greenhouse gases, such as carbon dioxide ($CO_2$), methane ($CH_4$), nitrous oxides ($N_2O$) and others. The molecules of these gases contribute differently to global warming. For example, the impact of one methane molecule is 21 times higher than the impact caused by one carbon dioxide molecule [6]. This is why the impact of different greenhouse gases is usually converted to the equivalent impact that carbon dioxide molecules would have. Therefore, for carbon footprint calculations, $CO_2$ equivalents are used as a standard unit [2].
Anthropogenic climate change is caused by greenhouse gases, such as carbon dioxide ($CO_2$), methane ($CH_4$), nitrous oxides ($N_2O$) and others. The molecules of these gases contribute differently to global warming. For example, the impact of one methane molecule is 21 times higher than the impact caused by one carbon dioxide molecule [(Moss et al. 2000)](https://animres.edpsciences.org/articles/animres/abs/2000/03/z0305/z0305.html). This is why the impact of different greenhouse gases is usually converted to the equivalent impact that carbon dioxide molecules would have, resulting in $CO_2$ equivalents as a standard unit [(Gohar & Shine 2007)](https://rmets.onlinelibrary.wiley.com/doi/10.1002/wea.103). The basic formula for a consumption value $c$ and an emission factor $\epsilon$ is:

### Sources
```{math}
y_{CO^2} = \epsilon \cdot c
```

The CO<sub>2</sub>e emissions are calculated using emission factors from different sources:
- electricity: [carbon footprint (2023). International electricity factors.](https://www.carbonfootprint.com/international_electricity_factors.html)
- mobility: [mobitoool (2023). mobitool-Faktoren v3.0](https://www.mobitool.ch/de/tools/mobitool-faktoren-v2-1-25.html)
- heating: [GOV.UK (2023). Greenhouse gas reporting: conversion factors 2023](https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2023)

The specific emission factors for different activities are collected in [this emission factor table](https://github.com/pledge4future/co2calculator/blob/dev/data/emission_factors.csv).

The basic formula is:
`co2 emissions = consumption * emission factor`
### Emission factor sources

The CO<sub>2</sub>e emissions are calculated using emission factors from different sources:
- Electricity: [carbon footprint (2023). International electricity factors.](https://www.carbonfootprint.com/international_electricity_factors.html)
- Mobility: [mobitoool (2023). mobitool-Faktoren v3.0](https://www.mobitool.ch/de/tools/mobitool-faktoren-v2-1-25.html)
- Heating: [GOV.UK (2023). Greenhouse gas reporting: conversion factors 2023](https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2023)

* location based emission reporting
The specific emission factors for different activities are collected in [this emission factor table](https://github.com/pledge4future/co2calculator/blob/dev/data/emission_factors.csv).


## 1 Electricity

Electricity emissions are computed from country-specific production mixes [carbon footprint (2023). International electricity factors.](https://www.carbonfootprint.com/international_electricity_factors.html). These are the mix of fuels used by local power stations.
Electricity CO<sub>2</sub>e emissions are calculated from country-specific production mixes [(carbon footprint 2023)](https://www.carbonfootprint.com/international_electricity_factors.html). These are the mix of fuels used by local power stations and, therefore, the basis for location-based reporting.

### Calculation of a share of electricity use

If the electricity consumption is only known for a building or building complex and emissions should only be computed for parts of the building, the total consumption and an estimate of the share of energy use (approximated from the share of the building area) can be provided.


## 2 Heating

Heating emissions are computed as CO<sub>2</sub>e emissions [carbon footprint (2023). International electricity factors.](https://www.carbonfootprint.com/international_electricity_factors.html).
Heating CO<sub>2</sub>e emissions depend on the type of burned fuel. Fuel types may be, for example, oil, gas, coal or biogas. The emissions are calculated using emission factors from [(carbon footprint 2023)](https://www.carbonfootprint.com/international_electricity_factors.html).

### Calculation of a share of heating consumption

Heating emissions depend on the type of burned fuel. Fuel types may be, for example, oil, gas, coal or biogas. The emissions are calculated using emission factors from
If the heating consumption is only known for a building or building complex and emissions should only be computed for parts of the building, the total consumption and an estimate of the share of energy use (approximated from the share of the building area) can be provided.


## 3 Mobility

The `co2calculator` allows to quantify the emissions for individual business trips for different modes of transport. The CO<sub>2</sub> equivalent is a function of the distance travelled in km. This distance may either be directly provided, or it may be computed from given start and stop locations using [distances.py](https://github.com/pledge4future/co2calculator/blob/dev/co2calculator/distances.py). In the latter case, the coordinates of the locations have to be retrieved by geocoding and then the travel distance between the locations is computed. Next to the distance or the locations, the user defines the mode of transport and its specifica.
CO<sub>2</sub>e emissions from the mobility sector are calculated using emission factors from [(mobitoool 2023)](https://www.mobitool.ch/de/tools/mobitool-faktoren-v2-1-25.html). They depend on the mode of transport, such as car or bicycle, and the distance travelled. This distance may either be directly provided, or it may be computed from given start and stop locations using [distances.py](https://github.com/pledge4future/co2calculator/blob/dev/co2calculator/distances.py). In the latter case, the coordinates of the locations are retrieved using geocoding before the travel distance between the locations is computed (for details, see [Geocoding](#heading-target)).

(heading-target)=
### Geocoding

Geocoding is done using the [openrouteservice](https://openrouteservice.org/dev/#/api-docs) geocoding service, which is built on top of the [Pelias](https://github.com/pelias/pelias), a modular, open-source search engine for the world.
Geocoding is done using the [openrouteservice](https://openrouteservice.org/dev/#/api-docs) geocoding service, which is built on top of [Pelias](https://github.com/pelias/pelias), a modular open-source search engine for the world.

To find airports [geocoding_airport](https://github.com/pledge4future/co2calculator/blob/5ac4e624f742f404299276e013f0f0194e5ba6da/co2calculator/distances.py#L45), we use [Pelias search](https://github.com/pelias/documentation/blob/master/search.md) with the search text "Airplane" + **IATA-code**. To find train stations inside the EU [geocoding_train_stations](https://github.com/pledge4future/co2calculator/blob/5ac4e624f742f404299276e013f0f0194e5ba6da/co2calculator/distances.py#L156), we use the train station database of [Trainline EU](https://github.com/trainline-eu/stations). For train trips outside of the EU and other modes of transport, we use [structured geocoding](https://github.com/pelias/documentation/blob/master/structured-geocoding.md) ([geocoding_structured](https://github.com/pledge4future/co2calculator/blob/5ac4e624f742f404299276e013f0f0194e5ba6da/co2calculator/distances.py#L98)). The structured geocoding parameters are:
- country: highest-level administrative division supported in a search. Full country name or two-/three-letter abbreviations supported
Expand Down Expand Up @@ -77,71 +84,3 @@ Bus | x 1.5 | Adapted from [GES 1point5](https://labos1point5.org/ges-1point5),
Train | x 1.2 | Adapted from [GES 1point5](https://labos1point5.org/ges-1point5), who were advised by Frédéric Héran (economist and urban planner).
Plane | + 95 km | CSN EN 16258 - Methodology for calculation and declaration of energy consumption and GHG emissions of transport services (freight and passengers), European Committee for Standardization, Brussels, November 2012, [Méthode pour la réalisation des bilans d’émissions de gaz à effet de , Version 4](https://www.ecologie.gouv.fr/sites/default/files/Guide%20m%C3%A9thodologique%20sp%C3%A9cifique%20pour%20les%20collectivit%C3%A9s%20pour%20la%20r%C3%A9alisation%20du%20bilan%20d%E2%80%99%C3%A9missions%20de%20GES.pdf), p. 53
Ferry | ??? | ???

### Specifica of the modes of transport

Mode of transport | Fuel type | Size | Occupancy | Seating | Passengers | Range
------------ | ------------- | ------------- | ------------ | ------------- | ------------- | -------------
Car | [diesel, gasoline, cng, electric, hybrid, plug-in_hybrid, average] | [small, medium, large, average] | - | - | [1..9] | -
Train | [diesel, electric, average] | - | - | - | - | - (assumes "long-distance")
Bus | [diesel] | [medium, large, average] | in % [20, 50, 80, 100] | - | - | - (assumes "long-distance")
Plane | - | - | - | [average, Economy class, Business class, Premium economy class, First class] | - | - (determined from distance)
Ferry | - | - | - | [average, Foot passenger, Car passenger] | - | -

These specifica determine how high the emission factors (in kg CO<sub>2</sub>e/km) are. If these parameters are not specified, the default values in the following table are used:

### Default values of the specifica of the modes of transport

Mode of transport | Fuel type | Size | Occupancy | Seating | Passengers | Range
------------ | ------------- | ------------- | ------------ | ------------- | ------------- | -------------
Car | [average] | [average] | - | - | [1] | -
Motorbike | - | [average] | - | - | - | -
Train | [average] | - | - | - | - | [long distance]
Bus | [diesel] | [average] | [50 %] | - | - | [long distance]
Plane | - | - | - | [average] | - | - (determined from distance)
Ferry | - | - | - | [average] | - | -

### Range categories

Trips are categorized based on their ranges, which can be used later for analysis and visualization purposes.

- Very short haul: < 500 km
- Short distance: 500 - 1500 km
- Medium distance: 1500 - 4000 km
- Long distance: > 4000 km

## 4 Commuting

Emissions from commuting are also quantified individually for each mode of transport [calc_co2_commuting](https://github.com/pledge4future/co2calculator/blob/2e102a0971dda57423fe7aef9958d0e61358248c/co2calculator/calculate.py#L445). For a given mode of transport, the user provides the average weekly distance travelled in a given time period (`work_weeks`). Available transportation modes are:
- Car
- (Local) bus
- (Local) train
- Tram
- Motorbike
- Bicycle
- Pedelec

### Specifica of the modes of transport

Again, the characteristics of the modes of transport influence the specific emission factors.

Mode of transport | Fuel type | Size | Occupancy | Seating | Passengers | Range
------------ | ------------- | ------------- | ------------ | ------------- | ------------- | -------------
Car | [diesel, gasoline, cng, electric, average] | [small, medium, large, average] | - | - | [1..9] | -
Motorbike | - | [small, medium, large, average] | - | - | - | -
Train | [diesel, electric, average] | - | - | - | - | - (assumes "local")
Bus | - | [medium, large, average] | in % [20, 50, 80, 100] | - | - | - (assumes "local")
Tram | - | [medium, large, average] | in % [20, 50, 80, 100] | - | - | - (assumes "local")
Bicycle | - | - | - | - | - | -
Pedelec | - | - | - | - | - | -

### Aggregating to the group's level

If we assume that a representative sample (`n_participants`) of the entire group (`n_member`) entered their commuting data, we can obtain an estimate of the commuting emissions for the entire group:

`group_co2e = aggr_co2 / n_participants * n_members`
with `aggr_co2` the sum of the CO<sub>2</sub>e emissions of all participants.



## 8 References

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