Don’t be afraid but be aware…

Conferences are great to meet people but they obviously have an impact on the planet.

Based on MobileHCI 2018 attendance numbers in Barcelona (closest city that hosted MobileHCI in the last few years), and with an estimation of 300 attendees at MobileHCI 2021, the conference in Toulouse would yield around 575.000kg of CO2 emission just for the travels of its participants. Which is roughly equivalent to the electric consumption of 540 households in a year. Offsetting these carbon emissions would require planting around 3830 trees. However the community is taking action! Since 2019, SIGCHI conferences include Sustainability Chairs into their program committee. We are thrilled to continue the trend with MobileHCI’21! We are not seeking perfection (yet 😉), but to do steps in the right direction.

Our approach

We built upon what UIST’19, IHM’19, CHI’19 and CHI’20 have done or intended to do. We are trying to be as transparent as possible by documenting what we do. All details are or will be provided. Our goal is that other conferences from the HCI community can benefit from it.

One last thing! Feel free to re-use this webpage and build upon. The text and the documents we use are or will be freely available. If you want to contribute, you are more than welcome to contact us. We hope this might help future conference chairs, or anyone that needs to take actions in event organization, for instance as a list of items to look at.

Contacting previous Sustainability Chairs

Let’s start with the obvious. In order to prepare our plan, we started by looking at what previous conferences had done, as well as the sustainability statement written by our General Chairs for their conference proposal. We then contacted the different Sustainability Chairs of the past conferences for more details (CHI 2019, UIST 2019, IHM 2019 and UIST 2020).

Carbon footprint

Our general goal is to reduce the carbon footprint of the conferences. However it should not be at the expense of the conference attendance. We therefore aim to undertake sustainable actions in order to balance out the carbon produce, by either directly cutting through the emissions or offsetting them through tree planting programs (such as local or more global ones), following CHI 2019 and IHM 2019 examples.

Fully virtual Program Committee meeting

As CHI, our community flagship conference, the Mobile HCI 2021 general and paper chairs have decided to hold a fully virtual Program Committee. Although difficult to organize, this is a critical decision that greatly helps reduce carbon emissions. Less flights. Less is more.

Public Transport

Going downtown from the airport can be done by taking public transport (tram). The city has two subway lines. For short distances, a bike rental service is also available (the first 30 minutes are free), more information can be found on the Toulouse official website. In general, most places are at walking distance and clustered within the downtown area (hotels, restaurants, conference center).


French food is known worldwide, having a taste of it is mandatory! However French are fierce meat lovers. This is therefore a tricky subject on which we decided to compromise. We will provide vegetarian food for the morning and afternoon breaks, as well as for the evening reception and we will only propose a meat option with a low carbon footprint (eg. local duck meat) for the reception dinner.

During the conference, we will aim at providing healthy, local and ethical food. Water fountains will also be available at the conference center.

Conference centre

Following CHI 2020, we will look at the use of AC in the conference building. We will be in control of the AC thermostat, which allows us to drop the conference room temperatures by a few degrees.

We will also avoid using conference center screens (which will therefore be turned off during the conference) and will prefer using a control number of printed papers and SV hours to help participants navigate between the rooms.

Reducing web traffic

Loading a web page generates carbon emissions due to data exchanges happening between the server and the client. Using Website Carbon Calculator you can estimate your web page carbon footprint. In an attempt to minimize our footprint, our web chairs (kudos to Emeline Brulé & Katta Spiel) developed the MobileHCI 2021 website using Grav, a flat file lightweight CMS, and customize it to reduce the file size to only what’s needed, which results in pretty much no javascript. Another benefit is long term sustainability helping the maintenance from one organizing committee to the next.

To go further, when possible, images from the website are stored in a vectorial formal (svg) rather than bitmap formats (png, jpeg, …). When bitmaps are required, we downgraded image resolutions to the minimum resolution required. For instance, if images are displayed as 100px per 100px squares, we match the corresponding image file resolution to a 100px per 100px.

Numerous guides exist to help authors create video figures and/or video presentations of their work (for instance the CHI 2020 guide for video figures and the Medium SIGCHI guide for remote presentations). However we would like to complete those guidelines with a final step aiming at compressing the different videos. This step can collectively make a huge difference if all videos are compressed from (typically around) 200MB to few dozens of MB. It will play out at every re-upload but more importantly every download or youtube view! Here are some tools that can be used:

  • ffmpeg: to compress videos with with reasonable bitrates (around 1.5Mbps for the video chanel and 128kbps for the audio one), you can use the following command: ffmpeg -i originalvideo.mp4 -c:v libx264 -b:v 1.5M -c:a aac -b:a 128k outputvideo.mp4
  • Handbrake: free software that helps you convert and compress videos.

Symbolic gestures, we organizers, tried to follow

We provided a list of symbolic gestures to the organizers. Our goal was not to have every member adopting them but rather encouraging them to give a shot at developing new habits that may stick. Feel free to make some of the following yours!

  1. Reducing our use of video stream during remote meetings.
  2. Favouring instant messages over emails for internal communication.
  3. Reducing the size of our emails (eg. deleting previous mails content while replying).
  4. Typing URLs directly instead of searching for them.