Smart thermostats can sense your activity around the home, but that creates privacy concerns. Here's what you should know.

Heating in these halls is provided by ... one of your neighbors may have a window open, signaling to the thermostat that the rooms are colder than they are. These halls do not have air conditioning.

It's all handled by these new brilliant little sensors that stay in constant communication with your home's heating and cooling. After using one, I consider it an essential part of my thermostat ...