the HVAC System,an integral part of building construction.

Now a days HVAC system is an integral part in building construction field.HAVC means heating, ventilation and air conditioning.
the ancient Romans had remarkably good radiant heating in some buildings,which was achieved by warming air and then circulating it in hollow floors and walls.In the dry climate of the middle east,people hung wet mats in front of open doorways and achieved a  crude form of evaporative air cooling.In Europe,Leonardo da Vinci designed a large evaporative cooler.
The development of HVAC was begun scarcely 100 years ago.Central heating system was developed in the nineteenth century,and summer air conditioning using mechanical refrigeration has grown into a major industry only in the last 60 years.A typical person in modern society may spend up to 90% of each day indoors.It is not surprising,therefore,that providing a healthy,comfortable indoor environment has become a major factor in our economy.
Air conditioning:
many of the peoples air conditioning simply means "the cooling of air".for engineering purpose this definition is neither sufficiently useful no accurate.the real definition is-
Air conditioning is the process for treating air in an internal environment to establish and maintain required standards of temperature,humidity,cleanliness,and motion.
Sound control can be considered an auxiliary function of air conditioning system.even though the system itself may be the cause of the problem.the air conditioning equipment can produce excessive noise,requiring additional sound attenuating devices as part of the equipment.
The definition of air conditioning given hare is not meant to imply that every HVAC system regulates all of the conditions described.A hot water or steam heating system only control air temperature,and only during the heating season.A warm air system also control temperature in winter only.by adding humidifier we can also control humidity.
Air conditioning system used for newer commercial and industrial buildings and luxury apartment houses usually provide year-round control of most or all of the air conditions described.For this reason,it is becoming increasingly popular to call complete HVAC systems environmental control systems.
Components: most heating and cooling system has following basis components-

• A heating source
• A cooling source
• A distribution system
• Equipment for moving air or water
• devices for transferring heat between the fluid and the room

the development of an HVAC system for a building consists of a number of steps.these are- 

• design 
• installation
• operation &regular maintenance
• service

If anyone want to learn about HVAC ,the most important thing is to locate a proposed building and follow the HVAC system development through planning ,installation,and operation.This experience will help him a lot to get a clear concept about HVAC beside study.