Sense is a bright-orange box that sits in your electrical breaker box and gives in-depth insight into your home's entire power usage. The whole system is quite clever and--thankfully--free of any monthly charges. But it learns very slowly, and that's likely to frustrate you. Sense ($299 at Amazon) works by electromagnetically listening to the power flowing along the two hot wires that run from your electric meter to your breakers. By measuring the current flow a million times each second, Sense can observe changes in load with precise detail and, based on a machine-learning database, attempt to identify the footprint of different devices from the noise they generate. This means it can tell you exactly how much energy different appliances in your house use, and it does all of this without requiring sensors or smart plugs on each device.

Sense is a bright-orange box that sits in your electrical breaker box and gives in-depth insight into your home's entire power usage. The whole system is quite clever and--thankfully--free of any monthly charges. But it learns very slowly, and that's likely to frustrate you. Sense works by electromagnetically listening to the power flowing along the two hot wires that run from your electric meter to your breakers. By measuring the current flow a million times each second, Sense can observe changes in load with precise detail and, based on a machine-learning database, attempt to identify the footprint of different devices from the noise they generate. This means it can tell you exactly how much energy different appliances in your house use, and it does all of this without requiring sensors or smart plugs on each device.