Almost all modern buildings have one or more HVAC systems integrated with their design, installation, and control systems. The three major functions of heating, ventilation and air conditioning are interrelated, especially with the need to provide thermal comfort and acceptable indoor air quality within reasonable installation, operation, and maintenance costs. HVAC systems can be used in both domestic and commercial environments. 

• Heating
• Cooling
• Air Conditioning 
• Ventilation 
• Refrigeration