HVAC: The basic functions of heating and cooling systems

HVAC: The basic functions of heating and cooling systems

HVAC is a term you will have heard, but how does this system of technologies work exactly? Heating, Ventilation and Air Conditioning (HVAC) is a general term for one of the most important technological developments in modern engineering. In its most simple explanation, an HVAC system’s primary objective is to maintain our homes and other buildings at comfortable temperatures (be it cool or warm) through the implementation of machines such as air conditioners and ventilation networks.

However, HVAC systems have many more complex functions that go beyond just keeping a building cool in the summer or warm in the winter. HVAC systems can filter the air we breathe, control moisture levels and work to maintain healthy concentrations of oxygen and carbon dioxide. HVAC’s applications are quite broad, but if there’s one common feature amongst these interrelated technologies, it’s the achievement of thermal comfort.

The key applications of HVAC systems

HVAC systems have come a long way since the invention of the first air conditioning unit in 1851. Technological developments throughout the 20th and 21st centuries have allowed us access to myriad HVAC systems and machines; from small, portable air conditioners and heaters used in the home, to large, complex heating and cooling systems for industrial applications. The advent of central cooling and heating has made for a much more comfortable way of life, and current technological advancements in the HVAC field are changing faster than ever before, particularly in regard to sustainability.

Some of the basic principles of HVAC applications include:

  1. Heating – To increase the temperature of any central indoor space like a room, office or entire building.
  2. Cooling –  To decrease the temperature of a space.
  3. Humidifying – To increase the moisture level of a space via the introduction of water.
  4. Dehumidifying – To mechanically eliminate excess moisture from a space.
  5. Filtering – To clean, filter or otherwise remove contaminants or unnecessary particles from within an indoor space.
  6. Ventilating – To introduce and move external air into an indoor space.
  7. Movement of air – To physically manipulate the movement of indoor air via ducts, fans and other forms of auxiliary ventilation systems.


In short, principles of HVAC are drawn from a diverse combination of engineering concepts such as thermodynamics, heat transfer, fluid mechanics and mechanical engineering in general.

The two types of HVAC systems

HVAC systems and their respective equipment can be divided into two categories – central systems and local systems. Central HVAC is located off-site, usually in a contained room and delivers air through a system of ducts. Generally speaking, central systems rely on a combination of air and water to provide their functions – be it cooling, heating, ventilation, humidifying, etc. These systems are most often found in industrial applications versus household ones.

On the contrary, local HVAC systems are located on-site and do not require complex ductwork to deliver air or other functions. Local systems are what most of us are familiar with, and generally, can be found in homes and workplaces in the form of air conditioners, heaters, fans, dehumidifiers and air exhaust systems.

Delivering thermal comfort through ingenuity

No matter the purpose of the system, an experienced MEP engineer will utilise the appropriate configurations and equipment to ensure the building users’ comfort. This will go alongside solutions to make the system more efficient and sustainable, enhancing the occupants’ comfort and improving the management’s bottom line.

As this month progresses, we will be diving into the various complexities of HVAC and how these different components work together to effectively deliver thermal comfort. DJHC always analyses the most appropriate configuration for our clients, ensuring the optimal system for the project. Find out more in the case studies section.



Leave a Reply

Your email address will not be published.