Killing “Zombie Hours”: how StreamSCAPES imagines greener and better streaming

 

Where the Video-on-Demand sector should focus next: turning small, interface-level nudges into system-wide energy savings, closing data gaps in distribution, and aligning Europe’s emerging rules with proportionate, practical action.

 

One relevant insight from the StreamSCAPES Set‑the‑Stage workshops is that the green transition of our sector has matured faster in content production than in digital distribution and consumption. Practitioners agreed that the biggest, most immediate wins now lie in the last mile (on screens and in the app experience) where simple design choices can cut wasted energy without denting viewer satisfaction. The workshops repeatedly highlighted ‘zombie hours’ (devices playing when no one is watching) and other forms of unattended or unnecessary playback as a priority target. Meanwhile, the industry still lacks harmonised measurement for streaming itself, leaving room for inconsistent claims and greenwashing, and making it harder for smaller services to move beyond compliance to real reductions.

 

The finding that should reframe our priorities

StreamSCAPES participants reported that interface‑level nudges are already delivering measurable reductions: prompts such as ‘Are you still watching?’, gentler defaults that dim or hibernate idle screens, audio‑only modes for listening use‑cases, and better power‑down coordination between TVs and set‑top boxes. None of these degrade experience; all of them quietly eliminate waste. The same discussions underlined why this matters: across multiple studies, the consumption phase dwarfs the energy used by networks and data centres, so curbing waste at the device is pivotal. The BBC’s models show the consumption phase accounts for ~90–93% of total energy for video, with distribution typically 6% and media preparation around 1%. In other words, removing unattended playback and right‑sizing delivery are not ‘nice to haves’—they are the new efficiency frontier.

Multiple independent assessments converge on the same conclusion: end‑user devices dominate the footprint of watching video. The Carbon Trust’s widely cited estimate for one hour of VOD in Europe (around 55 gCO2e) emphasises that the viewing device is the largest driver of impact; larger screens and brighter settings lift energy, while laptops and smartphones draw less. BBC analyses reach a similar result, with home equipment responsible for over 90% of total energy across platforms, and a 2025 BBC white paper again confirming consumption as the dominant stage. Meanwhile, the International Energy Agency tracks data centres and data transmission networks at about 1–1.5% of global electricity each, showing that efficiency gains in the core have largely contained growth despite soaring demand. That puts even more of the practical leverage with platform UX and with device defaults.

 

Practical wins: where distribution can cut waste now

Workshops highlighted a pragmatic three‑bucket approach. First, tackle what platforms control: encoding roadmaps, leaner front‑end codebases to avoid extraneous data generation, and smarter storage and compute strategies (including scheduling energy‑intensive jobs when the grid is cleaner). Second, press for ecosystem options—multicast‑assisted delivery and peer‑to‑peer during peaks—where collaboration with Content delivery Networks (CDNs) and ISPs yields systemic gains. Third, be honest about end‑user devices: it is where most energy is spent, but also where platforms can influence behaviour without hectoring users, through defaults and subtle prompts rather than blunt restrictions. Recent trials of Multicast‑Assisted Unicast Delivery (MAUD) suggest up to 50% less bandwidth during peak live events and demonstrable flattening of traffic peaks in live pilots—encouraging signals that the “greener equals cheaper and better‑quality” triangle can hold in practice.

 

What can the platforms do

• Inactivity prompts and coordinated shut‑off: default shut‑down after extended pause; turn off the set‑top box when the TV powers down (and vice‑versa)
• Audio‑only modes where appropriate: preserve the soundtrack while the screen sleeps for news, talk shows or music videos.
• Eco‑defaults that do not shame users: credibly labelled quality tiers (1080p/720p) rather than pushing 4K by default; gentle guidance on downloads where it genuinely helps.
• Darker UI themes and brightness‑aware patterns: small per‑household savings that scale. Note the nuance—energy gains from dark mode depend on display tech (OLED vs LCD), so claims must be device‑aware.

Crucially, none of the above should push responsibility entirely onto viewers. The first duty is to eliminate waste in the chain you control; then help households make easy, comfortable choices that align quality with efficiency.

 

Mind the measurement gap

If distribution is the next frontier, measurement is the missing gap. StreamSCAPES participants repeatedly flagged inconsistent methodologies, vendor‑specific emission factors and blurred boundaries (not least around end‑user device attribution) as blockers to credible action. The workshop view was pragmatic: combine spend‑based baselines with supplier activity data where you can; use sector‑specific tools for streaming; align with the Greenhouse Gas Protocol; and prioritise reductions over box‑ticking. Europe’s policy context can help if it remains proportionate. CSRD is already driving better disclosure in large entities and, through value‑chain pressure, lifting standards among smaller counterparts. Ecodesign and energy labelling rules for electronic displays nudge devices themselves in the right direction. The next step is transparency from CDNs, ISPs and cloud providers on real energy use, power source mix and emission factors—without it, ‘apples‑to‑apples’ comparisons aren’t possible.

 

References

StreamSCAPES D1.1 Set‑the‑Stage Workshops Report (2025). Horizon Europe StreamSCAPES (ID 101177811).

BBC R&D. ‘How much energy is used to deliver and watch TV programmes?’ (2020; figures updated June 2021). Available at: https://www.bbc.com/rd/articles/2020-09-sustainability-video-energy-streaming-broadcast

BBC R&D White Paper WHP 424 ‘Revisiting the Energy Footprint of Broadcast and Streaming’ (2025). Available at: https://downloads.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP424.pdf

Carbon Trust. ‘Carbon impact of video streaming’ (2021). Available at: https://www.carbontrust.com/our-work-and-impact/guides-reports-and-tools/carbon-impact-of-video-streaming

Ofcom. ‘Carbon emissions of streaming and digital terrestrial television’ (2022). Available at: https://www.ofcom.org.uk/siteassets/resources/documents/research-and-data/technology-research/2022/carbon-emissions-of-streaming-and-digital-terrestrial-television-3.pdf?v=322186

IEA. ‘Data centres and data transmission networks’ tracker (accessed 2025). Available at: https://futurimmediat.net/news/data-centres-and-data-transmission-networks-analysis-iea

BT Group & Edgio. ‘World’s first MAUD‑enabled CDN’ announcements (Aug 2024) and TVBEurope trial coverage (Mar 2025). Available at: https://newsroom.bt.com/bt-group-and-edgio-announce-worlds-first-maud-enabled-content-delivery-network/

Directive (EU) 2022/2464 on corporate sustainability reporting (CSRD). Available at: https://eur-lex.europa.eu/eli/dir/2022/2464/oj/eng

European Commission. Electronic Displays: Energy Labelling and Ecodesign (product page); Regulation (EU) 2019/2021. Available at: https://energy-efficient-products.ec.europa.eu/product-list/electronic-displays_en

Ars Technica. ‘Dark mode doesn’t save much power…’ (Feb 2025) — BBC R&D study context. Available at: https://arstechnica.com/gadgets/2025/02/small-study-suggests-dark-mode-doesnt-save-much-power-for-very-human-reasons/