EV charging carbon emissions reduction automation continues to work perfectly btw!
(My automation uses the Electricity Maps API to document hourly updates of the grid’s carbon emissions; it calculates the average and the standard deviation of the past 48 hours of readings.)
ALT Screenshot of three notifications from the Home Assistant app for iOS, all of which are titled “Ioniq 6 Notification” and say that the car’s AC charge limit has been changed due to electric grid carbon emissions: Two hours ago, set to 50% because emissions were 0.36 standard deviation below average; one hour ago, set to 60% because 0.66 below average; now, set to 50% because 0.44 above average.
Sep 20, 2026 · 8:08 PM UTC
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The rule I came up with: Set the EV charge limit to 50% by default; raise to 60% if emissions are 0.6 to 0.69 standard deviation below average; raise to 70% if 0.7 to 0.79 standard deviation below average; raise to 80% if 0.8 standard deviation or more below average.
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