History of HVAC
A long-form timeline of how humans learned to heat, cool, and clean the air — from Roman hypocausts to today's electrification push.
Last updated: 2026-09-15
Timeline
c. 100 BCE
Roman hypocausts
Heated air from a furnace flowed under floors and inside walls of Roman baths and villas.
c. 400 BCE+
Persian windcatchers
Badgirs channeled breezes and evaporative cooling to cool desert buildings.
Medieval
Chimneys and stoves
Open hearths gave way to chimneys and cast-iron stoves in medieval Europe.
1741
Franklin stove
Benjamin Franklin's metal stove delivered more heat with less fuel and smoke.
1800s
Steam and hot-water heating
Steam radiators and hot-water systems heated buildings and cities.
1902
Willis Carrier's AC
Carrier invented modern air conditioning to control humidity in a printing plant.
1920s
Movie theaters
Cooling theaters drew summer crowds and spread public demand for AC.
1930s–50s
First home air conditioners
Window and early central units brought cooling to American homes.
1940s–60s
Forced-air furnaces and central air
Postwar suburbs adopted forced-air furnaces and central air as standard.
1987–2010
Refrigerant story
CFCs, the Montreal Protocol, R-22 phase-out, R-410A, and today's lower-GWP transition.
1990s+
SEER standards & DOE
Federal efficiency standards and the DOE raised minimum AC and furnace efficiency.
2000s+
Heat pumps go mainstream
Cold-climate heat pumps made heat pumps viable across more regions.
2010s+
Smart thermostats
Connected thermostats added learning, scheduling, and remote control.
2020s
Electrification
States push building electrification toward heat pumps and efficient electric systems.
HVAC in California
Title 24 sets energy standards; HERS testing verifies ducts and efficiency; wildfire smoke drives filtration; heat waves lead to cooling policy; and the state pushes toward electrification.