Why does one property use much more electricity than the others?

An annual invoice gives only one figure and does not explain whether a property itself consumes more, whether other guests consume more, or whether something is broken. With a metering module per property you see consumption at any moment, even when the property is empty: if the meter keeps running, that indicates the property itself; if it runs only during stays, it is due to guest use. That does not make maintenance unnecessary and does not explain occasional spikes, but it does give you a foothold with structural differences.