Air conditioning, done by HVAC (heating, ventilation, and air conditioning), is essential for contemporary societal comfort. Commercial air conditioning is especially important in the design of medium to large industrial and office buildings such as skyscrapers. These places use large scale air conditioning systems, such as packaged rooftop units, commercial control systems, etc, available in Marietta. Air conditioning systems contribute to health and comfort, worker productivity and economic vitality. They are now commonly used in stores, restaurants, offices, hotels, hospitals, and other public places. Environment-friendliness of such units has been under the scanner for many decades. Hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and to a lesser extent ammonia and absorption are used for cooling. High efficiency also translates in savings in electricity. Commercial dealers usually provide technical help in installing the systems, and are often involved right from building design.