This project is being developed for the OFAR4All research project, with the aim of measuring and transparently presenting CO2 emissions from online data traffic.
The measured results are computed and displayed on the app.
The application tracks the users data usage and calculates the emitted CO2-values based on a computational model, which is currently under development by ZHAW. In order to be able to classify consumption properly, CO2 equivalents are given that are familiar from everyday life.
The application supports English, German and is currently only available for android devices.
The CO2 value is composed of several factors. Those factors are based on their respective global warming potential (IPCC GWP).
More specifically, the calculated CO2 value consists of the following factors:
- Factor for production of the devices involved in the network traffic
- Factor for the operation of the devices involved in the network traffic
- Factor for the disposal (EOL) of the devices involved in the network traffic
- Factor for the power consumption of the device the app is running on
All those factors are used in combination with various other influencing factors like the geo-location, the usage time and the network connection (WiFi, Mobile) the traffic was generated at, to calculate the caused CO2 pollution of the users internet behavior.
The determination of the average values is based on an ongoing scientific study of the HTWG Konstanz in cooperation with the ZHAW Zürich.
co2footprint_tracker
├── app
│ └── src/main
| ├── java/de/htwg/co2footprint_tracker
| | ├── database
| | ├── enums
| | ├── helpers
| | ├── model
| | ├── services
| | └── utils
| └── res
└── gradle/wrapper
| Folder | Description |
|---|---|
| root | contains necessary parts for initializing and building the app |
| app | contains all necessary parts directly regarding the functionality of the app e.g. source code, build files |
| src/main | contains the main source code, viewing components and android manifest |
| java/de/htwg/co2footprint_tracker | contains only source code which belonges to logic and functionality of the app |
| database | contains source code that only belongs for managing databases |
| enums | contains source code for establishing own datatypes |
| helpers | Contains source code for helper methods. These helper methods, in contrast to utils, also contain advanced logic and functionalities |
| model | Contains source code for data transfer objects between classes, databases, views etc. |
| services | Contains source code for services that are run in background and do tasks for fullfilling the main app goal |
| utils | Contains source code for simple helpers e.g. string converters, constants etc. |
| res | Contains resource files and static content used by the source code e.g. bitmaps, fonts, etc. |
| gradle/wrapper | Contains files for gradle |
The image shows the core design of the application with the most important classes.
The following is a list of relevant design decisions and their technical relevance to the app.
For gathering the devices data usage and the generated network traffic, the application uses the NetworkStatsManager API provided by the operating system. Via the NetworkStatsManager it is possible to access all information in regards to the Network usage. The provided data is divided in discrete time periods (Buckets) which can overlap from time to time. More information on the NetworkStatsManager: https://developer.android.com/reference/android/app/usage/NetworkStatsManager
For saving information and relevant data, the application uses a simple SQLight-Database. The database contains the information about the network traffic fetched from the NetworkStatsManager. These information are fetched periodically after every minute and saved in a table together with other calculated values. To save storage space, every 24h hours, the collected data of the last day gets accumulated and saved while the old data is being wiped.
To work correctly, the application must always be open in the background. This is ensured via a Foreground Service, which ensures that the app is not closed by the system (memory optimizer). If the app should be closed by the system or the user, it will restart itself.
To determine the current location of the user, the application uses the LocationHelper API provided by the operation system. The location is determined at the first installation of the App (onStart) and always when reopening it (onResume) and is then saved in the background for further calculations.
To identify which type of device is currently used, the application calculates the device-indepentent pixel density and checks, if the density of >= 600. If it is bigger, then the device is considered a tablet, if it's smaller the device is identified as a smartphone. For the values and the calculation see: https://developer.android.com/training/multiscreen/screensizes
With the help of the connection to the Google Cloud, configuration files and information can be provided online, which flows directly into the app without having to create a new build of the app. For example, tips can be adjusted directly via Google Cloud Config without having to deploy a new app version.
The values used for the CO2 Equivanlent Cards are currently only placeholders and not correctly scientifically determined values. They were collected from various sources and are only intended to give an impression of how possible representations could look. They just vaguely represent the actual facts. The actual values are computed by the amount of co2, divided by some quotient. This may change in the future. For now the CO2 equivalents are composed in the following way:
As of now, the cars quotient for calculating the distance driven is 139. For the user this results in the following information:
As of now, the planes quotient for calculating the distance flown is 201. For the user this results in the following information:
As of now, the light bulbs quotient for calculating the lightning duration is 20. For the user this results in the following information:
As of now, the quotient for calculating the streaming duration on Netflix is 100 *. For the user this results in the following information
As of now, the quotient for calculating the amount of battery charges on a smartphone is 2.35875.
This quotient is based on the following functions:
-
avg g CO2e/kWh in EU 2019: 255
-
avg smartphone battery capacity 2500 mAh, 3.7V = 0.00925 kWh
-
0.00925 kWh * 255 g CO2e/kWh = 2.35875
-
X g CO2e / 2,35875 g CO2e = X Times
For the user this results in the following information:
It is assumed, that one tree absorbs 200kg of CO2 during its live. Following this assumption, the quotient for calculating the amount of trees to be grown is 200000 For the user this results in the following information:
The Application needs a couple of permissions in order to function properly.
Network Permission: This Permission is needed to access the internet to retrieve information from the Google Cloud Config (e.g. new Tips).
Phone State Permission: This Permission is needed to access the information for the current cellular network information. We use this information to determine which network type is currently used (2G, 3G, 4G, WiFi).
Location Permission: This Permission is needed to access the GPS Module to get the current location. The calculation of CO2 values needs the location for different factors.
Usage Stats Permission: This Permission is essential for accessing the network statistics of the device. This permissions allows the application to access the NetworkStatsManager API and gather the data usage of different apps.
IMPORTANT NOTICE: The application is not able to see which websites you visited or what you did/are doing in your different applications. The Application only accesses the information, which are already collected by the operating system. Furthermore are all required permissions are not used/transmitted in other ways by this app.
