Not sure if it's a modern feature per se. But if you have a tankless heater, you can set the temperature to be a little bit above the hottest water you require.

Not sure if it's a modern feature per se. But if you have a tankless heater, you can set the temperature to be a little bit above the hottest water you require. If you have a heater with a tank, you need to keep it hot enough to prevent bacterial growth, specifically those that cause legionnaire's disease. I've seen systems with a tank, heat pump and solar panels, where the system automagically drives up the temperature to kill bacteria every once in a while. Supposedly that's more efficient than keeping it hot all the time.