How did homes stay cool in Florida before air conditioning?
Tuesday, June 19, 2018
Both of us grew up in South Florida in the mid-20th century and each year Miami emptied out in the summertime as the “snowbirds” headed north to escape the sweltering heat. Central air conditioning changed all that, making it possible to have cool, low-humidity indoor air during the hot months. It has also been a key ingredient in the rapid population growth in Florida and other southern states since then.
But older Florida homes had a number of ingenious, built-in ways to beat the heat. We remember some from our childhood and learned other, even older, techniques that take advantage of prevailing breezes and reflect or exhale the heat from a home, during our years remodeling old Conch houses in Key West. Here’s a list of eight old-time ways to keep a house cool:
Large windows - Positioning windows near corners of the home for cross-ventilation was critical. Casement windows wrapping around a corner were a post-World War II design used to catch a breeze. Tall double-hung windows could be opened at the top or bottom, depending on what air flow level worked best. Jalousies and awning windows were popular throughout the 1960s because the entire area of the window could be opened for air flow.
Louvered shutters and awnings - Both of them shaded window openings to keep the heat of direct sunlight from entering the interior of a house, while still allowing ventilation.
Porches - They provide deep shade on exterior walls to eliminate the radiant heat load on walls in direct sunlight. Screened sleeping porches were also popular, usually on a second floor corner, to catch a cool evening breeze.
Whole-house fans - Usually located in the ceiling of the hallway to bedrooms, they accomplished two things at once: sucking outdoor air in through the windows and simultaneously pushing hot attic air out at roof vents.
Transoms (a small louvered panel over a door) and louvered interior doors - While not great for bedroom privacy, they allowed the all-important cross-ventilation breezes to flow across a room with the door closed.
Ceiling fans - The air feels cooler under a ceiling fan because it evaporates perspiration and creates a wind chill effect, even though it does not actually cool the air temperature.
Masonry Walls - Thick stone, brick, or concrete block walls absorb heat during the day and slowly release it at night, reducing the temperature difference between the them. This was not ideal on the hottest days of summer in South Florida, where it did not get that cool at night, but useful during the rest of the year.
Metal roofs - Especially popular in Key West, and memorialized by Tennessee Williams in his play “Cat on a Hot Tin Roof,” a metal roof really does reflect heat back into the sky and keep the home below it cooler. Today they come with reflectance rating so a consumer can evaluate how well the roofing bounces the heat. White painted metal actually has a higher rating then shiny silver-color metal. Some new homes accomplish similar heat reflectance by a layer of metal foil on the underside of roof sheathing in the attic.
While older homes were built to open up, catch the breezes and deflect the sun, modern homes are designed to seal and insulate the building envelope to conserve their conditioned air. This is fine, except after a hurricane when the electricity is down and the a/c is dead. That’s when we yearn for an open, subtropical home of years gone by.
Also, see our blog post How did people stay cool in Key West before air conditioning? for a listing of the unique passive cooling features of the old Conch Houses in Key West.
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To learn more about heating and air conditioning systems, see these other blog posts:
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