Air conditioner:  An appliance, system, or mechanism designed to dehumidify and extract heat from an area. Usually, this term is reserved for smaller self-contained units such as a residential system.

Duct: Specialised housing for the air flow.

Dehumidifier: A dehumidifier is the equipment that extracts and removes humidity from the air. It works by cooling air to the point where water turns to liquid from vapour form and then the liquid is removed.

Fresh air intake: An opening through which outside air is drawn into the building. This may be to replace air in the building that has been exhausted by the ventilation system or to provide fresh air for combustion of fuel. 

Furnace: A component of an HVAC system that adds heat to air or an intermediate fluid by burning fuel (natural gas, oil, propane, butane, or other flammable substances) in a heat exchanger.

Heat exchanger: A heat exchanger is the part of the system that transfers heat from the hot parts of the machine or a system to the cold parts of the machine or system.

Heat transfer: Heat transfer happens when heat moves from one area to another. It is an important and vital step in the process of cooling a space.

Radiant ceiling panels: Usually, metal panels suspended from the ceiling, insulated from the building structure. The primary cooling/heating agent temperature is close to the room's temperature.

Radiant floor: A type of radiant heating system where the building floor contains channels or tubes through which hot fluids such as air or water are circulated. The whole floor is evenly heated. Thus, the room is heated from the bottom up. Radiant floor heating eliminates the draft and dust problems associated with forced air heating systems.

Radiation: The transfer of heat directly from one surface to another (without heating the intermediate air acting as a transfer mechanism).

System: General term used to refer to the set or a subset of components that perform a specific HVAC function within a building. 

Thermostat: A thermostat is a system that monitors and regulates a heating or cooling system. It can be used to set the desired temperature at which it keeps the environment either heated or cooled.

Zoning system: A zoning system sections a building or space into zones which are controlled independently of each other. This is beneficial when different areas or rooms of a building have different temperatures as well as when the desired temperatures in different rooms are different. Temperature is controlled by different thermostats.