Which is more energy efficient: heating a given volume of water all at once, or in two batches?

I have an electric kettle, and a large urn of room temperature filtered water, which I use for tea. If I'm making tea for two people who aren't going to be drinking it at the same time, is it more energy efficient to boil the water separately, all at once, or no difference?

#AskFedi #physics #thermodynamics #tea #IdleThoughts

@Fishercat yeah my understanding is that if you're using identical systems, you'd still lose more energy to the container/atmosphere by doing it in two batches instead of one? but there's definitely variance between kettle efficiency and stovetop efficiency (i believe kettle is probably more efficient?)
but if your goal is to have hot tea for two different serving times, youll probably end up committing to losing that extra energy for the quality?
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