Smart thermostats and home security systems are two devices that an owner can install and run from a phone: the thermostat that controls a home's heating or cooling, and the security system of sensors, a siren and smoke detectors that watches the home. They are sold mainly in the United States, where most homes have central heating and cooling, and where many families install their own alarm systems.
A thermostat is a switch with a temperature sensor. It turns the heating or cooling on when the room is too cold or too hot, and off when the room reaches the set temperature. In an American house, one thermostat on the wall usually controls a furnace, which heats air and blows it through ducts to every room, and a central air conditioner. Indian homes rarely have central heating. Most cool each room with its own air conditioner and its remote, so this product is much less common in India.
A smart thermostat adds a Wi-Fi connection, an app and a schedule. Take, for example, a family in Columbus, Ohio, in January, when it is −5 °C outside. They set the thermostat to keep the house at 20 °C (68 °F) in the evening, and at 16 °C (61 °F) at night and while they are at work. On a Saturday, they leave for a trip. From the app, they lower the setting to 13 °C (55 °F), just warm enough to stop the water pipes from freezing. On the drive home, one of them raises it again, so that the house is warm when they arrive. Keeping the house cooler when no one is home lowers the heating bill.
A do-it-yourself home security system is a set of small wireless devices: sensors on the doors and windows, motion sensors, a keypad, a siren and smoke detectors. They report to a base station over low-power radio chips. The detectors themselves are built on sensor chips that sense movement or smoke. Say a smoke detector senses smoke while the family is away. The base station sounds the siren and sends an alert to their phones. If they pay a monthly fee for professional monitoring, staff at a monitoring centre also receive the alarm. They call the family and, if needed, the fire department. Most systems also link to home security cameras, so that the family can see what set off the alarm.
Both devices follow the three-layer design of IoT architecture: firmware on the device, an app on the phone and the maker's cloud between them. If the home Wi-Fi fails, a good system keeps working on its own, and some send alarms over a mobile network as a backup.
A home security system differs from a camera on its own. A camera records what happens. A security system detects an event, such as a door opening or smoke, and calls for help.