The carbon footprint in terms of electricity usage of viewing one hour of video-on-demand streaming is three times that of boiling an average electric kettle. The energy usage of viewing on a 50-inch television is 90 times that for watching on a phone. On average, the viewing device is responsible for half the overall energy usage. These are some of the notable factors identified in a paper published by the Carbon Trust on the Carbon Impact of Video Streaming, with input from the BBC, ITV, Sky and BT, funded by Netflix.

The paper was commissioned by DIMPACT, a collaborative initiative between researchers at the University of Bristol and several media organisations, and published by the Carbon Trust, based in London, which was established in 2001 to advise on sustainable energy strategies.

The research concluded that increases in video resolution affect the bitrate required to transmit video data but have only a very small change in the carbon impact.

Lead author of the report, Andie Stephens of the Carbon Trust, said: “Our white paper shows that the carbon footprint of watching an hour of streamed video content is minor compared with other daily activities. As the electricity grids continue to decarbonise, and telecoms network operators increasingly power their networks with renewable electricity this impact is set to reduce even further.”

The BBC has studied its own total energy use across satellite, terrestrial, cable, telco and online distribution. For the 2019-2020 financial year it was 1,789 GWh, comparable to 0.6% of electricity use in the United Kingdom in 2019. This equals 0.55 million tonnes of CO ₂ equivalent emissions, which was approximately 0.1% of UK carbon emissions in 2019.

Of all platforms, satellite was found to have the largest energy footprint, accounting for 40% of the total, followed by terrestrial at just under 20%, which was above cable and telco television, with iPlayer at 141 GWh, or 8% of the total.

The vast majority of this energy usage comes from consumption, through millions of devices in homes. This accounts for almost all the energy usage of satellite distribution.

Considering energy usage per viewer hour, the iPlayer was just below satellite and cable, but almost double that of terrestrial television transmission.

Of course it depends on which device it is viewed. Smartphones and tablets consume relatively little energy, compared to a set-top box and a large-screen television, which consume half the power of a desktop computer and monitor.

Carbon Impact of Video Streamingis published by the Carbon Trust and is available from its web site. BBC Research and Development published ‘The carbon impact of streaming: an update on BBC TV’s energy footprint’ in response.