Smart thermostat
Smart thermostats are devices that can be used with home automation and are responsible for controlling a home's heating and/or air conditioning. They perform the same functions as a Programmable thermostat as they allow the user to control the temperature of their home throughout the day using a schedule, such as setting a different temperature at night. Like a Connected thermostat they are connected to the Internet, they allow users to adjust heating settings from other internet-connected devices, such as smartphones. This allows users to easily adjust the temperature remotely. This ease of use is essential for ensuring energy savings: studies have shown that households with programmable thermostats actually have higher energy consumption than those with simple thermostats, because residents program them incorrectly or disable them completely.[1][2] Smart thermostats also record internal/external temperatures, time the HVAC system has been running and can even notify you if your air filter needs to be replaced. This information is typically displayed later on an internet-connected device.
Learning thermostats
Some smart thermostats, such as the Nest thermostat, can automatically learn when the house is likely to be occupied, and when it is likely to be empty. This allows it to automatically pre-heat or pre-cool the house, so that it's at a comfortable temperature when a resident arrives. If the residents' lifestyle changes, these smart thermostats will gradually adjust the schedule, maintaining energy savings and comfort.
Connected thermostats
A Connected thermostat is one that can be controlled through an internet connection, but will not provide analytic information.
Zoned systems
Rather than controlling the temperature of the whole house, zoned systems can control individual rooms. This can increase energy savings, for example by heating or cooling only a Home-office and not the bedrooms and other areas that are empty during the day.
Learning zoned systems
The most advanced smart thermostats combine both: they are able to learn when each room of a house is normally occupied and automatically schedule the heating for that room appropriately. Currently, the only such system available for home use is Heat Genius.