When was air conditioning invented?

For millions of Americans, the only escape from 2023’s record-setting summer heat was heading indoors to the comfort of air-conditioning.

The whir of AC units is a near-constant sound in much of the country. Almost 90% of homes in the U.S. have central or single-unit air conditioning. This is a dramatic increase in the last 40 years. In 1980, less than 50% of U.S. homes had air conditioning.

So how long has air conditioning been around, and where is it headed next?

When Was Air Conditioning Invented?

The seeds of modern air conditioning were sown in 1902, when 25-year-old engineer Willis Carrier was asked to maintain a standard level of humidity in a printing facility.

Carrier’s solution? A series of metal pipes chilled by the compression and expansion of a gas. Their cold exterior collected condensation, drawing water from the air like a glass of ice collects water on its sides. The result was the first modern dehumidifier.

But to Carrier, a side effect was even more interesting: It reduced the air temperature.

Carrier realized this might be significant, but his employers at Buffalo Forge were unimpressed. Rather than pursue it themselves, they allowed Carrier and a group of fellow engineers to take the patents and form a new company. Today the Carrier brand has sales of around $20 billion annually.

Today’s near-universal availability of air conditioning would seem almost magical to anyone alive at the turn of the 20th century. Initial public reaction was skeptical, and attempts to control the temperature seemed unnatural.

For Carrier and other AC pioneers, it began a decades-long struggle for acceptance. Ultimately, it took advances in technology and a post-war spike in homeownership for the masses to truly accept air conditioning.

The Evolution of Air Conditioning

Methods of cooling date back to antiquity. Ancient Egyptians used evaporative cooling to control temperatures, and Benjamin Franklin studied similar techniques in the 18th century. In the 19th century, Dr. John Gorrie created a small refrigeration unit to ease the suffering of malaria patients.

Here’s a timeline for the development and acceptance of air conditioning as we know it:

• 1902: Willis Carrier invents the modern air conditioner. The initial models featured dangerous, flammable materials like ammonia and propane for cooling.
• 1911: Carrier publishes a paper, “Rational Psychrometric Formulae.” It remained the basis for air conditioning engineering for more than a century.
• 1914: Installation of the first residential air conditioner, at the Charles Gates mansion in Minneapolis.
• 1928: Non-flammable, non-toxic chlorofluorocarbon (CFC) gas developed as a refrigerant.
• 1931: H.H. Schultz and J.Q. Sherman invent the window air conditioner. The cost far exceeded consumer demand, with the units often costing more than a new home.
• 1938: Fredrick McKinley Jones invents portable air conditioning, allowing refrigerated trucks to transport perishable goods much farther.
• 1940: The Packard becomes the first car with factory-installed air conditioning.
• 1944: The G.I. Bill provids veterans assistance with purchasing a home, transforming American homeownership and spiking demand for air conditioning.
• 1945: Affordable window air conditioners patented by Robert Sherman.
• 1987: First set of efficiency standards for air conditioners (SEER) from the Department of Energy.
• 1990: Driven by the Clean Air Act and the discovery CFCs damage the ozone layer, the U.S. government mandates a phase-out of CFCs in favor of hydrofluorocarbons (HFCs).
• 2022: Recognizing that HFCs dramatically amplified the greenhouse effect, U.S. senators ratify the Kigali Amendment, beginning the HFC phaseout. Possible replacement refrigerants include ammonia and propane.
• 2023: SEER 2 goes into effect, encouraging higher efficiency and greater energy savings on air conditioner usage.

Air Conditioning Today and Tomorrow

Home air conditioning has improved by leaps and bounds since Willis Carrier thought to put a fan on a dehumidifier. And air conditioning will continue to evolve, incorporating new technologies to be more convenient and more efficient.

We can expect to see:

• New refrigerants: As mentioned above, we’ve gone through several types of refrigerants, all found to pose hazards to users or the environment. There are a number of proposed replacements, including gases used in the original air conditioners.
• More smart tech: Smart phones and voice assistants control many thermostats. Some heating and cooling systems use motion detectors to determine how often and hard they run.
• More zoning. Zoned systems and ductless mini-split HVAC units allow temperature control room-by-room. This results in energy savings and an environment matching each individual’s preference.
• More heat pumps: Heat pumps are essentially air conditioners that work in reverse, heating a home as well as cooling it. They’re extremely efficient and becoming more robust with each passing generation. Tax incentives and lower operating costs are driving more homeowners to switch to heat pumps.
• More environmentally friendly tech: Modern air conditioning units are constantly becoming more efficient, and some are truly wearing their green designs on their sleeves.