How to Reduce the Carbon Cost of Video Conferencing: A Concept

We’re nearly two years into this global pandemic. Those of us fortunate enough to work from home have traded in our daily commutes for Zoom, Meet, Teams, Skype and Co.

And while “the overall energy saved as a result of less commuting is still around four times larger than the increase in residential energy consumption” (source: IEA), we still leave a carbon footprint in home office.

Judging by the way my computer fan revs up, video calls seem to be data (and energy) hogs. According to a recent study,

Just one hour of videoconferencing or streaming […] emits 150-1,000 grams of carbon dioxide […], requires 2-12 liters of water and demands a land area adding up to about the size of an iPad Mini. But leaving your camera off during a web call can reduce these footprints by 96%.

So how could we reduce data transmission during video calls?

1. We could redesign video chat apps to be greener

First off, what’s the point of a video conference if you don’t use video?

I’ve found there situations where you simply don’t need all participants’ cameras and/or mics on:

• When only one person is doing the talking
• When only one person is doing the presenting
• If there are more participants in the call than there is screen real estate to display all their images
• If a participant is not really participating
• When you’re on a slow or spotty connection
• When you’re running out of battery

The problem is: video chat apps were not designed to use less data or make it easy for the user behave in an energy-saving manner.

We could redesign them to be green by default: instead of “always on”, the default should be “mostly off”. And we could nudge people to turn off cameras and audio when they’re not needed and thus reduce upstream data transfer.

This is how it could work:

• When a participant enters Presentation mode, all other participants’ cameras and microphones are shut off (or at least they are prompted to do so) by default. Default options reinforce a desired behavior or help drive a specific outcome.
• Giving users immediate feedback on their actions in red (= bad) and green (= good) makes it easier for them to cut back energy use
• Inactive participants can be muted and hidden
• Video quality can be set to “low” by default
• Camera streaming is turned off when on a slow/spotty connection or low on battery

Instead of displaying the data transfer rate or estimated kilowatt hours – information that makes you think too much – the user receives “ambient” feedback on data usage using colors and smilies, which is easier to process. As Professor Jaap Ham says in the Podcast How to Save the World, “Giving feedback directly at the right moment in time and in place where you’re performing the behavior – that’s most effective for actually changing behavior.”

Demo

2. We could fix things under the hood

On the technical side, video chat apps could likely be optimized to save data and energy while making the user experience more performant (i.e. faster).

Now without getting into video codecs (something I know basically nothing about), I took a quick peek at which resources Google Meet loads during a call and noticed right away:

• Alternative image formats such as WebP for images are not served for profile pictures (I “squooshed” the largest pic, reducing it by 68% from a 20.1 kb JPG to 6.4 kb WebP, or by 81% to a 3.9 kb AVIF)

• The same image is downloaded in several sizes, which is redundant

• Fonts (379 kb) could be reduced by subsetting or by using SVG for the icons that are needed

  

  

Now I’m not trying to pick on Google Meet – I think it’s one of the best video chat apps around. I’m just trying to make the point that I’m sure all video chat apps could “cut the fat” pretty easily. And especially since those tools have become something of a necessity during a global pandemic, even small savings in data transmission must translate to noticeable energy savings in the end.