What is HVAC?

HVAC is Heating, Ventilation & Air Conditioning. 

HVACR is Heating, Ventilation, Air Conditioning & Refrigeration. 

This is the field that deals with heating or cooling your place. 

There are the HVAC consultants (design), HVAC contractors (implementation/installation) and HVAC distributors (manufacture of machines) and HVAC suppliers (sale of machines) and HVAC Service & Maintenance. 

HVAC Engineers from a consultancy will design the HVAC system, HVAC Engineers from the suppliers will select the machines as per designed heat load and the HVAC Engineers from the contractor will implement the selected machines as per the HVAC design in the building. The HVAC technicians (from Contractor or Supplier) will do the fitting, testing and commissioning and service of the machines. 

Heating - Required in cold places or countries, where temperatures drop below comfortable range (usually during winter) for humans (The World Health Organization (WHO) recommends a minimum indoor temperature of 18˚C or 65˚F). Heating is mainly a must for countries closer to the poles.

Cooling -  Required in hot places or countries, where temperatures rise above comfortable range (usually during summer) for humans (WHO recommends indoor temperature of 18-26˚C or 65-79˚C). Cooling is mainly a must for countries closer to the equator (Tropical and sub-tropical countries).

Ventilation - Required wherever rooms are completely closed off from the outside air. As per the ASHRAE standard 62.1, minimum fresh air required is 2.5 lps or  5 cfm per person and 0.06 cfm per sq.ft area or 0.3 lps per sq.m area.

Air Conditioning - Process of of cooling (removing heat and moisture) or heating (adding heat) from the interior of an occupied space to improve the comfort of occupants.

Refrigeration -  Process of cooling a space to a specified temperature below the ambient one for purpose of preserving things at that desired temperature. Similar to as air conditioning, but for things, not humans.

*ASHRAE - The American Society of Heating, Refrigerating and Air-Conditioning Engineers

*ASHRAE standard 62.1 (Ventilation for Acceptable Indoor Air Quality)
*Air flow: lps - liters per second
*Air flow: cfm - cubic feet per minute
*Area: sq.ft - square feet
*Area: sq.m - square meter.