What is HVAC?

HVAC (Heating Ventilation and Air-Conditioning) systems accomplish processes such as heating, cooling, Ventilation, humidification, or dehumidification. Knowledge of the behavior of such systems is essential for the analysis and design of air¬-conditioning devices, cooling towers, and industrial processes involving hygroscopic materials like textile and paper requiring close control of the vapor content in air. These processes are represented in psychometrics charts (The study of systems involving air and water vapor mixtures is known as psychometrics.)


Process in which the moisture or water vapor or humidity is added to the air without changing its dry bulb (DB) temperature is called humidification process.


Process in which the moisture or water vapor or the humidity is removed from the air keeping its dry bulb (DB) temperature constant is called the dehumidification process.



HVAC means (Heating, Ventilation and Air Conditioning) . Generally, we say Air Conditioning.

Why we need air conditioning?

About 10 years ago, HVAC systems were considered as ‘Luxury items’. But with the changes of cultural, social, economical , environmental and health values and norm of the world , HVAC systems have become an indispensable part of the building . In the modern society a common person spends around 95% of day and night time indoors. The modern technical innovation of production has proved it’s essentially.

1.Temperature Control Environment:

The temperature control environment is essentially needed in all spheres of world either it is industrial, commercial, residential, public or plantation sectors. The required temperature is maintained either by heating or cooling the air.


Humidification is controlled either by removing or adding the moisture in air in a particular place. The humidification varies as per requirement of objects. Some of the industries cannot perform its production without maintaining controlled range of humidity level. We use humidifier and dehumidifier to control this function. It may be built- in the HVAC system or place a unit separately called humidifier and dehumidifier. The most best equipment for this purpose is precision unit. Pharmaceutical, electronic, digital printing textile, laboratories , sweets and operation theaters of Hospitals are the main type of sectors where it is very commonly used.

3.Maintaining Air Quality (Cleanliness) -Clean Rooms:

Healthy and hygienic air quality is maintained by filtration of different efficiency level which prevents entry of dust and particulate matter and supplies. Hygienic , clean air and ventilation is achieved by supply filtered fresh air from outside. The different types of filters like hepa filters G9, G4 or other grades are used to achieve 99.9% hygienic and clean air . The hygienic air is checked through gauges/ check meters before entering air in side.

4.Ventilation and Air Changes.

Healthy oxygen in air and exhaust of contaminated air of room is necessary for health. Air changes in the indoor environment are also essential for proper ventilation. The air born particulars in duct and noise is also part of pollution environment. The acoustic liners or sound attenuators are used to control noise levels so that non pollution air in indoor environment can be provided.

Factor to consider for selection of HVAC system:

HVAC systems are available in different types to control indoor environment whereas the objectives are same. It differs with respect to different applications and conditions.

Following factors are necessary to consider:

1.Nature of Application:

It mean where the HVAC is required to use either in hotels , marquees, pharmaceuticals, textiles, Plastic manufacturing industries, commercial and residential building, etc.

2.Capacity Calculation of Air Conditioning Area:

  • Calculate total area or volume where HVAC is need to install
  • Calculate dissipating heat load of machines, stock Or end object required temperature like dyes in plastic industries etc.
  • Calculate” K” factor of the building area.
  • Calculate humidification of the area.
  • Calculate impact of fresh air added
  • Confirm the air sealed area or opening closing of doors
  • Note down ambient temperature of the location and specially local area ambient temperature where HVAC is need to install.
  • 3.Operational Reliability of HVAC System:

    The HVAC system should very reliable in sense either it is feasible for required operational times i.e. 24/7 hour operation of plant, 12 hour operation of plant or 3 to 4 hours. The quality and capacity of the HVAC system should be selected accordingly. Some industries like sugar mill, cement, power plants remain in operation for long period continuously.

    4.Special requirement of object for which HVAC system is required like atomic energy, Pharmaceutical industries.

    5.Capital and operational Cost factor:

    The HVAC system should be financially viable. Its operation cost should be very economical along with capital cost.

    6.Energy conservation/consumption (billing Cost):

    Energy saving is the major issues to the world now- a- days. The entire researchers of the world are busy in endeavors to design such a HVAC system which consume very minimum energy cost. Especially green energy revolution is in vogue . Its EER should be very ideal.

    7.HVAC Life:

    HVAC equipment should selected which carry maximum life at maximum productivity level. Certainly it reduces production cost.