Humans have been trying to cool down their homes for thousands of years. Probably for tens of thousands of years, but humans have done it with some success for at least 3,000 years.
Back in those early days, in China of 1,000 B.C.E., people used hand fans – a LOT of hand fans. These fans were a very common accessory, and were used often, and in many social settings. A thousand years later, the Romans used their stupendous aqueduct system for cooling – sending water circulating through the walls helped give some chill to the air. In the Middle East at that time, people constructed humongous wind towers to make natural breezes much stronger and more refreshing.
The Beginnings Of The Modern Air Conditioner
At the beginning of the 20th century, an inventor named Willis Carrier created a machine that pushed air over a series of coils holding cold water. This mechanical box was the first modern air conditioner, and the Carrier company continues to operate today.
That initial air conditioner was more about humidity than temperature. Carrier’s box kept the humidity low. The first major use for Carrier’s invention was at the Sackett & Wilhelms printing plant – moisture was messing up their paper and ink, and Carrier’s dehumidifier helped protect the company’s assets.
Eventually, people replaced cool water with refrigerants – first R22 refrigerant, and nowadays the more environmentally-friend R410A refrigerant. Kept in a closed loop, this substance can go back and forth between being a gas and being a liquid. In the process of changing state, the refrigerant absorbs and releases heat.
Today, HVAC units have become more energy-efficient. Smarter motors and larger surface area for heat exchange have let these systems use less energy to heat and cool a home.