What is the meaning of HVAC? Heating, Ventilation and Air Conditioning is the full form of HVAC, which is the applied science of keeping our buildings in a comfortable range of temperature, humidity and air quality1. It also includes keeping smaller areas at the extremes. So a refrigeration unit or a climate controlled hothouse would also fall under the HVAC umbrella.
Probably as old as fire, the ability to heat our living spaces meant mankind could move into areas previously off limits. Even in the most sophisticated systems used today, the basic laws are the same as they were with the first fire—create a heat source and move the heat generated around. How this happens depends on the medium – water or other fluid (hydronics), forced air, or electricity2.
The difference today comes in the ability to more efficiently move heat to where it is needed at a lower cost and with environmental considerations in mind. One of the tasks of the HVAC technician is to evaluate the building and match the needs to existing systems.
The complexities of modern systems means HVAC training covers a broad area of expertise3, with physics, electronics and building dynamics part of the mix. Technicians sometimes specialize in a particular area or even a certain manufacturer’s equipment. The advantage of this is a shorter, more focused training period. Certifications are often given by brand for this reason, although those in the industry often pick up a large assortment of certifications4
Ventilation means not just exchanging outside air for inside air, but also moving air throughout a structure. Air handling is more important than many realize. It includes filtering air to remove particulates, exchanging stale air for fresh, and keeping unwanted pockets of overheated or chilled air to a minimum. Modern, sealed buildings make this task even more of a challenge.
One example of the technical difficulties would be providing positive pressure, low particulate, “air curtain” for hospital operating rooms5. Another is how to efficiently move air around in a huge structure, like an airport6. Failure to properly handle air distribution can lead to sick building syndrome or even actual sicknesses like Legionnaires’ disease7.
Air conditioning means more than just lowering the temperature of the air. It also refers to lowering the humidity, filtering the air (dust or other particles) and may even include sanitizing the air (removal of smells and bacteria).
The essential mechanism is a heat pump. Heat is moved from one area to another. In fact, depending on the inside temperature, the same unit can act as either a heater or a cooling unit. The same process, first discovered in 1756, is used to alternatively compress a gas (into a fluid) and then let it absorb heat as it is allowed to expand again. From its humble beginnings, this idea has been improved upon until we can now cool the tallest skyscraper in one of the hottest locations on the planet8.