Early last year, I released statistics detailing the environmental impact of The Justice Syndicate. For the last four months, I have been exploring the different ways in which we could further reduce our carbon footprint.
Looking at the past statistics, clearly, the majority of the energy used by the show comes from charging the iPads (10776mAh). Therefore, it made sense to try and improve individual battery life.
For comparison, 10,776mAh of power is slightly more than a single iPad Pro's full battery capacity (10,307mAh).
SyndicateOS, the iOS application which powers the show relies on high-speed communication to perform many functions critical to the show, most significantly, the video syncing. This rapid communication puts significant strain on the iPads processors, thereby reducing battery life, especially during the playback of video or audio. The system checks playback position across all twelve devices twice a second, attempting to keep each iPad within 0.5 seconds of each other. While successful, if I were able to change tactic and remove this requirement, we would see a significant drop in power usage.
Removing such an integral part of the system required an overhaul of the core syncing system. Removing a poll-based system* and instead, introducing a new bespoke predictive system. Applying algorithms to predict positioning ahead of time – allowing the host device to target individual iPads before they become noticeably out of sync (thereby also reducing max latency to less than a 1/10th of a second!). It also accounts for variable network interference and packet loss, meaning this system can now be hosted from a crowded, public router — opening up the potential for using already in situ routers.
This change in tactic removed the need for constant position checking, shifting the processing load to spread across multiple devices, sharing the task more evenly.
And it worked! Battery life was improved, leading to an overall reduction of 5388MAh per show.
Leading to the new power statistics for the Justice Syndicate:
One show, twelve audience members = 0.014kg CO2e
Each audience member's impact = 0.001kg CO2e
These figures show that the improvements made to the iPad system have lead to a 26% reduction in CO2e in comparison to the previous version of SyndicateOS. The total CO2e produced is now < 0.02 hPACA.
For comparison, one show, 12 iPads, 12 audience members produce the equivalent CO2 to:
0.1% of boiling a mug of water in a kettle
(9.299kg CO2e, 1.8kw for 3 minutes)
0.004% of a single washing machine load
0.003% of a return flight London Gatwick, UK to Munich, Germany
* Short/long polling is when the client (iPad) periodically requests or 'polls' the server (macbook) for new informationDISCLAIMER iPad Mini 2019 Battery specifications - 5124mAh, 19.1 Wh. MacBook Pro 2019 Battery specifications - 58.2WH. Comparisons source: https://www.rensmart.com/Calculators/KWH-to-CO2. Flight CO2 calculator: https://co2.myclimate.org/en/flight_calculators/new