Why doesn't my Home screen update when I click the Refresh button? Why can't I load my diary?

If you previously installed the iPhone or Android app, and you do not see the Sign Up/Sign In screen after reinstalling, then go to the Guide screen (Home screen -> compass icon in top corner) and click Sign Out at the bottom of the screen. The Sign In screen will take a while to appear. The phone stored your original login credentials, but we have disabled last year's login credentials.

I forgot my password!

After signing out, go to the Sign In screen, click Reset Password, and follow the steps to reset your password.

How do I fill in the Pathway Diary? What do all these charts mean?

(a) Download this PDF guide that provides all the info currently available about the app: Pathway Diary, Footprint Feedback, and Week Plan features.

(b) In the app, the Guide screen (Home screen -> compass icon in top corner) has a centralized list of all the "help pages" for the app.

(c) You can also click on the Show/Hide Descriptions button in each section of the Home screen.

(d) For Pathways, click on the Info button on the Pathway Diary screen.

(e) Each of the other screens (Footprint, Compare, and Plan) has an Info button that displays a description of the screen.

(f) The Plan screen itself provides instructions for filling out the Week Plan.

How much cellular data will the app use?

The app will upload less than 3 megabytes per day while it is running in the background, if you are traveling for 2-3 hours in a day. If you move around all day, it could use up to 20 megabytes. Cellular data use cannot be disabled in the app, because we need to continuously update the carbon footprinting calculations.

When you are viewing your Pathway Diary or carbon footprint feedback, the app will use more data (but not much more), just like any other app that receives updates over the internet.

How much battery will the app use?

The app runs periodically in the background, only when the phone is moving, to collect the minimum amount of data needed for calculating footprints. For most smartphones, it will use less than 10% of the battery each day, if you are moving around for about 3 hours per day (20 to 30mAh per hour when the phone is moving).

If you are viewing the app on the phone's screen, it will require as much battery as any other app in active use.

iPhone Users:
If you normally don't keep location services on, it might seem like the battery drains much faster with GPS on. This is partially because lots of other apps and Apple services will start requesting your location and draining the battery--GPS itself doesn't use much of the battery. To improve battery use:

  • Go to Settings -> Privacy -> Location Services to shut off many location permissions, including:
  • Share my location: set to off
  • Except for Mobile Carbon Footprinting (which should be set to Always), set all other apps on the Location Services screen to 'Never' or 'While Using'
  • System Services: turn all of them off
  • System Services -> Significant locations: turn this off

Android Users:
If you normally don't turn on GPS/Location Services, the battery usage might seem high. This is because lots of other apps will also start requesting the phone's location, which drains the battery in addition to using the GPS itself. Shutting off location permissions for those other apps AND for specific Google features will help reduce battery use substantially. For Android 8.1 and above:

  • Settings -> Security & Location -> Click on LOCATION in the Privacy Section
  • At the bottom of this screen, click Google Location History, toggle it off so that Google isn't tracking all the time
  • This screen also shows recent location requests, e.g. Google is always there.
  • In the same Location screen, click on App-Level Permissions (or Settings -> Apps & Notifications -> App Permissions -> Location)
  • Toggle off anything that you don't want to request your location (especially Google), except for Google Play Services and Mobile Carbon Footprinting

I am concerned about sharing my location/GPS data.

We are following protocols to protect your privacy and personally identifiable information, and we have submitted these protocols to MIT's COUHES. Read the COUHES Consent to Participate info here. We hope that learning about your carbon footprint - and contributing to this research - will make the experience worthwhile.

Only your Display Name and simplified carbon footprint summaries will be visible to other participants. Trained investigators will only use your contact info to contact you directly about pilot project updates and to share automatically generated reports on your progress through the pilot project steps. Only one researcher (J. Cressica Brazier) has access to the data stored on the secure server, and she will never look at the GPS/pathway data directly - only you can see your pathway diary, using your phone. Your data will be anonymized and aggregated before sharing with other project investigators and research publications.

See more info in our privacy policy.


The app is crashing every time I try to open it!

This happens sometimes when the app version updates. On Android, go to Settings -> Apps -> MCF -> Storage -> Clear Data.

On iPhone, uninstall and reinstall the app, then go to the Guide screen (home screen -> compass icon in corner), click Sign Out, then Sign In again.

The app should start up and allow you to log in again. In the current version, your entrance survey will no longer be on the phone (don't worry, it is stored on the server!), but it will be available in the next app version.

It is so slow! The buttons are so small!

Yes indeed. It is handmade for research goals, so thank you for being patient with it!