CROSS CREEK — Fall is different in Florida. Trees change their colors, but so subtly that northerners may not notice. The heat rarely relents. Even as late as November, the sun’s heat was unyielding, beating down from a cloudless blue sky. The air was sticky and oppressive, pushing me to seek solace the way most Floridians do: I went inside.
Unlike 96% of homes in Florida, this one wasn’t air conditioned. Yet, it felt pleasant inside. A satiating cool filled the screened porch and living quarters. Light breezes provided a welcome relief from the oppressive humidity and kept the air from feeling sticky and stale. This Florida Cracker-style house was the home of author Marjorie Kinnan Rawlings. She knew the state’s heat and humidity, and captured it in her nonfiction book “Cross Creek”:
The sun seems to stand all day in one steady blazing. May is sometimes the hottest month of the year. One day in June a cloud passes over the sun in the late afternoon. The cloud spreads until all the sky is gray. The air is so still that even the restless Spanish moss hangs motionless. Although the sun is hidden, the atmosphere is stifling.
Originally built in the 1880s a half-century before air-conditioning, the property’s National Historic Landmark designation details how the design keeps the living spaces cool. The house was engineered for air to move. The main structure has two separate buildings under one roof with a dogtrot in between. This breezeway allows air to blow through. The home’s windows were also aligned to encourage cross breezes to cool the inside. The front porch is screened to do the same. The entire structure sits on concrete pylons, putting the house about two feet above the ground so air and water can flow underneath.
Before air conditioning, Floridians relied on design techniques like these to stay cool. Its dubious honor as the hottest, most humid state made Florida pivotal in the history of how people cooled their indoor spaces.
Florida’s Native people, too, pioneered cool interiors. In the 1830s, Seminole Indians living on the peninsula needed housing they could easily disassemble and move to escape U.S. troops that sought to oust them from their land. The result was the chickee.
Chickees create a comfortable environment by reducing radiant heat and promoting airflow. The thatched palm roof has a high pitch and hangs low to keep inhabitants out of direct sunlight. The low-hanging roof ensures more of the inside stays shaded longer, reducing the temperature.
Chickees also promote airflow; many were built without walls and raised off the ground. The design allowed cool air to flow underneath and through the structures.
Swamp fever
Early Floridians may have been able to beat the heat, but their open living spaces made them vulnerable to mosquito-borne diseases like malaria and yellow fever. A surge in those diseases in Florida opened another chapter in the history of cooling.
“People used to sit on their front porch, play guitar, play the fiddle. They would be outside in the cool of the evening, visiting with friends, talking to their neighbors, they had rocking chairs on every front porch in the south because it was cooler. So they would get exposed to mosquitos biting at dusk and dawn,” said entomology professor Rebecca Baldwin with the University of Florida’s Institute of Food and Agricultural Sciences.
Though Floridians didn’t know it at the time, those mosquitos were sickening them. Keeping windows open and spending time outside during the height of mosquito activity helped malaria take off in Florida.
“You're dealing with most people having been exposed to malaria in one way or another back then,” said Philip G. Koehler, an entomology professor emeritus at UF IFAS. “The most malarious part of the United States was in Perry, Florida. You don’t think of it these days, but we were the headquarters for malaria.”
Americans had all kinds of theories about what caused yellow fever, often called “the scourge,” and malaria, nicknamed swamp fever. An Apalachicola doctor named John Gorrie was convinced that the heat was causing the diseases.
"An adequate supply of pure air is the obvious remedy for the evils arising from the respiration of a noxious atmosphere, whether the impurity extend to a general vitiation, or arise from the neglect of cleanliness or ventilation,” he wrote in the Apalachicola Commercial Advertiser.
While the heat wasn’t the direct cause – that was mosquitoes – Gorrie was onto something. He thought that if indoor spaces could be better ventilated – and cooled – people wouldn’t get sick. He invented an ice machine to make warm air cold. The idea was to make ice, then blow air over it to cool the surrounding air.
Gorrie filed US Patent No. 8,080 for his machine on May 6, 1851. But the invention never took off during his lifetime.
The technology for air conditioning was finally popularized by Willis Carrier, who received a US Patent No. 808,897 for his invention in 1904. He called it the apparatus for treating air. As part of his patent, he claimed to have invented what we now call a condenser.
The condenser remains a fundamental part of modern air conditioning; it’s the system of coils that cools off refrigerant gas. Even after Willis Carrier refined the invention, it didn’t really catch on until after World War II.
“Once we weren't making planes and ships, we needed to put that towards something else,” said professor Mark D. Russell in UF’s Rinker School of Building Construction. By that time, too, he said, air conditioning technology had become more cost-effective.
Once people could afford it, they wanted A/C in their homes. But central, whole-house air conditioning was still more than a decade away.
"You didn't have whole-house air conditioning, that was really rare,” Russell said. “You had window shaker units, which was basically just a little small freezer unit that you put in your window."
Creature comforts
Creating a comfortable environment requires controlling temperature, humidity, radiant heat and airflow, Russell said. Just controlling the temperature is a serious battle against all the forces working to heat up a room.
“Typical summer day here, it's 90-some degrees out. That 90-degree temperature is trying to get into our space. Temperature always goes from the hottest space to the coldest space," Russell said. “If we want to keep it at 72, we've got to keep all this air moving out."
Then, you need the right size compressor to deal with however many bodies are going to occupy the space. People give off a lot of heat.
“A space is supposed to hold say 100 people, that's its max occupancy, you’ve got to make sure you get enough air, fresh air, enough AC in that room to keep it comfortable for 100 people,” said mechanical engineering professor Kurt Schulze of the UF Herbert Wertheim College of Engineering.
In Florida, the soaring temperatures have a sticky twin brother: humidity. So it’s never just the heat. Humidity is the amount of water vapor in the air, and Florida has plenty of water: from swamps to lakes to springs. All that H20 helps make Florida the most humid state in the nation, according to the Florida Climate Center.
So air conditioning has to do more than just dump cold air into a room. It pulls out moisture, making a room more comfortable by removing its humidity. If the air was just colder, but still humid, it would not be comfortable. "It'd be like walking into a wet beach towel,” Schulze said. “It'd be cool, but it'd be very uncomfortable."
The next AC advance
Modern air conditioning keeps our interiors cooler than a Florida cross-breeze ever could, not to mention keeping out noxious mosquitoes. But today, our overreliance on AC has placed a new burden on society and the Earth. A typical Florida household uses more than a quarter of its energy on air-conditioning. That intensity adds more carbon dioxide to the atmosphere, which then creates warming, which then requires more AC.
The compressor, fundamental to Gorrie and Carrier’s inventions, is the primary challenge. “The compressor takes a lot of energy,” Russell said.
Still, new ACs are becoming more efficient as years go by. At the same time, Schulze said, more sophisticated controls can reduce cooling during off-hours, or when people aren’t using a space. “Back when controls were less sophisticated,” he said, “we'd just be cooling that room even though there was nobody in it.”
Ultimately, the answer may blend the best designs from Florida history, with homes built to withstand an ever-warmer climate, and alternative cooling technologies challenging old-fashioned vapor compression.
Life in Florida was forever changed by air conditioning. It moved us inside, made us comfortable there and protected us from the harsh outside world. Now, our challenge becomes figuring out how to control indoor climate without harming the one on the outside.
