“Smart” electric meters, if not properly secured, allow criminals to sit outside your house and detect, via the wifi, whether you are at home or not by monitoring electricity usage.
The same is true, to a lesser extent, for water meters.
Today’s invention is to make these devices truly smart by having them send signals which say ‘electricity is being used’ in ways that mimic the detailed usage patterns of a particular household. These could be labelled, so that the homeowner wasn’t billed for energy use which didn’t occur.
In cold countries, you might actually want to run many of the devices as normal in order to maintain their functionality when you are away.