Systems for heating, ventilation and air conditioning–more commonly referred to by the acronym HVAC–have a fairly lengthy history that started with Willis Haviland Carrier’s fog-inspired creation of the first known air-cooling appliance.According to the Carrier Corporation website–the company started by the inventor and that still carries his name today–Carrier designed the inaugural device on July 17, 1902. He did so just one year after graduating from Cornell University with an engineering degree. The century-old unveiling of this machine that allowed for indoor temperature control marked the start of a brand new trade, as well as a new way of living for families and businesses around the world.It all started on a train platform in Pittsburgh, when the idea for Carrier’s invention came to him as he was staring through the fog that saturated the air on that particular day. It was then that Carrier realized he could move air through water to make fog, and that he could use this method to set moisture levels in the air. That same year Carrier finished the device designed to control humidity, and laid the foundation for air conditioning as we know it today.Since that fateful day at the train station, Carrier became known in the industry as “the father of air conditioning,” technology that has been credited for giving an economic shot in the arm to industries ranging from baking to manufacturing war supplies. With a way to cool the indoor air, movie theaters got a boost because audiences would come to the cinemas to catch a summer flick and escape the heat outside.HVAC systems have seen lots of improvements since Carrier created the first. Even with the more modern types of appliances, there are still lots of ways to make sure we are all running them as efficiently as possible.The Environmental Protection Agency and the Department of Energy suggest checking the air filter regularly, and changing it at least every three months. During heavy usage, the filter should be inspected monthly and replaced if it appears dirty. A clogged filter will make the system run slower and waste more energy.And just as vehicles require the occasional tune-up, so do HVAC systems. The government agencies recommend having those units serviced annually. Doing so will mean improved comfort at a lower cost.