> water heating by electricity [...] is rare because it's just so inefficient Entirely depends on the number of accommodation units per building, installation

> water heating by electricity [...] is rare because it's just so inefficient Entirely depends on the number of accommodation units per building, installation and ongoing maintenance cost of heaters and metering equipment, availability of gas and/or district heating, etc. It's certainly uneconomical to send heated water through expensive copper pipes in a building inhabited by only two singles when it's needed only for a shower in the morning, yet has to be kept running for hygienic reasons the remainder of the day.