Heating, Ventilating and Air Conditioning (HVAC) systems help to regulate the climate and maintain the indoor air quality of homes and commercial buildings. While sophisticated and reliable HVAC systems have become common in daily modern life, they have not always been so widespread. However, the principles that these systems operate on have long been known to scientists and engineers. Even though advances in the reliability and cost effectiveness of HVAC systems continue to improve, we enjoy very mature technology from this industry segment today.The modern air conditioning system has been in continual development since its invention in 1902 by Willis Haviland Carrier. The system that Carrier invented was used in a printing plant to regulate the temperature and humidity of the air, thus causing the process used there to operate more consistently and reliably. Thereafter, the demand for commercial air conditioning exploded and Carrier formed his own company. It was not until the 1950s, however, that residential air conditioning became wide spread.tdx 20 uses and reviews offers excellent info on this .
Because many early air conditioning systems used toxic and flammable gases to produce cooling, their utility was limited, so in 1228, Thomas Midgley, Jr invented the first chlorofluorocarbons (CFC) for use in refrigeration systems. This became popularly known by the DuPont brand name Freon, and it greatly enhanced the safety and reliability of refrigeration and air conditioning systems. However, in the 1970s scientific studies were starting to show that the release of CFCs into the air was depleting ozone levels in the stratosphere, resulting in higher incidence of harmful solar ultraviolet radiation reaching the earth’s surface. Because of government action, the use of all CFCs and related chemicals have been restricted and are expected to be completely phased out by 2010. Newer non-ozone-depleting refrigerants have been developed and are being phased into HVAC systems currently available on the market.
Our understanding of properly engineered HVAC systems was further advanced after the World Health Organization (WHO) issued a report in 1984 on Sick Building Syndrome (SBS). SBS was found to result from poor indoor air quality, and several solutions have since been developed to prevent this condition from developing. Proper maintenance guidelines for HVAC systems can help to prevent SBS; additionally, the use of an air-to-air heat exchanger can be employed to increase the amount of fresh outdoor air that is brought into a building without sacrificing energy efficiency. The current recommendation from American Society of Heating, Refrigeration & Air Conditioning Engineers is to provide 8.4 exchanges of air within a 24-hour period.