On a tangent, …
tldr: Hot water tends to majorly influence home/office energy use.
tl: Since living with rooftop solar here, I have noticed just how much energy is often drawn because of warm water. As in, in this house, you can see very noticeable usage spikes in the solar app whenever someone showers or washes dishes. I’ve completely given up on washing my hands with warm water and have reduced the amount of water I shower with. We’ve also started using the electric kettle for heating water because it means you usually only heat up about as much water as you actually need and the kettle has a pretty uniform 2kW power draw (which helps make it work on solar).
Obviously, there are different systems for heating water but one way or another, they tend to use a lot of energy and heat more water than necessary to higher temperatures than necessary. Unsurprisingly, other major energy wasters that most of us come into contact on a daily basis are also all about changing temperatures, namely home heating, AC and gas-powered motors (aka drivable heatings).
*sigh*
Of course you’re right that using heated water for washing your hands is a bit of a wasteful luxury. I just had some good memories of that bathroom.