There’s an old joke about college students hanging ice cubes in front of a fan to stay cool. It’s no joke – and it’s not new. Ancient Egyptians would hang wet palm fronds in the window so that passing breezes would be cooled by the moisture. In ancient India, reed mats soaked in water were hung in front of doorways to achieve the same effect.
The simple fact is that we have an average body temperature of 98.6 degrees, and any time the temperature exceeds that, we feel significant discomfort. To make matters worse, moisture creates a heat index that can make 80 degrees feel like 100 degrees. It’s curious that most of us find it easier to stay warm with a fire or other heating sources, but struggle to keep cool.
Some of the best methods were developed by ancient cultures living in hot, desert conditions. That’s no surprise. Necessity is the mother or invention. In fact, we might want to keep some of these concepts in mind as an energy conversation strategy — if not preparation for a day when the grid goes down.
Here’s the rundown and many ancient cultures combined these methods to keep cool when the weather outside was hot, hot, hot.
1. Wind towers
Wind towers are still prominent in the Middle East and other arid countries, where they were first used 2,000 years ago. Wind towers capture prevailing winds with internal vanes that work to not only force cooler air down, but would circulate to draw hot air up and out. Some wind towers collected rain water and used the evaporation of the water to further cool the captured air.
2. Water cooling
If you’ve ever walked into a valley next to a cold water spring on a hot summer day, then you’ve noticed the cooling effect that water has on the surrounding air. The same is true of towns and villages located next to large lakes, as prevailing winds passing over the water surface are naturally cooled. Many cities on the great lakes, from Chicago to Buffalo, are a good example.
The Romans used water from aqueducts to cool their homes by having the cold water run through channels in the walls of their houses and temples on its way to public fountains and baths. Cold water running through a course of pipes and exposed to the air in an environment also has a cooling affect.
3. Underground and in-ground structures
It’s obvious anytime you walk down into your basement on a hot summer day: The ground has a natural cooling affect. Conversely, an underground or in-ground home also stays warmer in the winter as the ground radiates more warmth than the air above it.
The ancient Anasazi Indians in Arizona and New Mexico built their homes and villages in the side of cliffs to not only shade their homes from the sun, but to take advantage of the natural cooling offered by the rocky, cliff face. Today, many homes are built underground or into the side of hills to capture this natural cooling and shading. In a pinch, you could always spend some time in the basement when the weather gets hot, or maybe it’s time to think about that underground house.
One of the most common occurrences of an underground shelter is a root cellar. Once again, the natural cooling of the ground served to offer an early form of refrigeration and preservation for root vegetables and other foods.
It’s no surprise that many ancient people lived in caves and grottos, not only for the protection from rain and snow, but for the same effect of cooling and heating relative to the ambient temperature outside.
The ancient Chinese get the credit for the invention of the first fans. The Persians had their variation, as well. The Persian version was simply a rug suspended from the ceiling that was pulled back and forth to create a breeze. It was fairly effective unless you were the guy who had to pull the rope to swing the rug.
The Chinese actually invented the idea of a bladed fan that swung from a central pivot. It was powered by a spring drive, and there were often multiple fans in the ceiling arranged in such a way that a directed breeze would be carried through the environment. Some of the more complex fan arrangements were powered by water-wheels.
5. Intelligent venting
The Navajo Indians in the Southwest desert cut trenches in the ground, covered with hides and soil, that led to the floor in the base of their hogans or mud huts. Toward the ceiling facing downwind of prevailing breezes, they cut vents. This created a natural draft that drew cooler air from the ground through a small vent of loose stones at one end of the trench, and into structure. Water, when there was a surplus, was sometimes poured into the trench to use the cooling effect of evaporation, to not only chill the air a bit more, but to provide natural humidity in the very dry environment of the desert.
The concept of intelligent venting is to either create cross-ventilation from prevailing winds, or to allow the thermodynamics of air to rise as it heats to create a ventilating draft. Many ancient structures had high ceilings and vents in the roof to facilitate this drafting principle. It’s an idea that is incorporated into almost every home built today.
6. Mud huts
You might not see a lot of mud huts in Architectural Digest, but across the African deserts they provided a natural cooling for their occupants. The dried mud was actually a coarse form of brick, and it would absorb the chill of the night and slowly release it during the day.
Today, there is an eco-friendly building system that features rammed-earth as the primary building material for the walls of structure. This has been shown to have the same characteristics of the mud hut concept.
7. Raised structures
Primitive homes on stilts are common in many areas where there is frequent flooding. However, some homes were built on stilts in very dry and hot areas to allow prevailing winds to pass both over and under the structure. This enhanced the cooling effect of the winds as they carried heat away from the entire home.
8. As above so below
In ancient India, many large homes and palaces were built over water, either natural or manmade, and featured roof-top gardens. The evaporation of the water under the structure cooled the entire building, and the moisture in the soil from the gardens above prevented the heat from radiating into the structure from the roof.
The ancient Indians, Greeks and Chinese also appreciated the importance of color, and many of their rooftops and buildings were white. White reflects sunlight, while darker colors absorb it and create higher temperatures within the building or structure.
While all of these ideas and techniques were effective, the most significant insight about ancient air conditioning is the way that they added these approaches to a structure to create a cumulative benefit. For example, a white structure made of brick built into a cliff side with a northern exposure, a roof top garden and vents in the roof, drawing air from a pit or channel in the ground. Wow, sounds like a good idea. It is — and it describes many of the towns and villages of ancient Greece.
It’s unlikely that any of us will be redirecting a spring or a creek under our homes to help with cooling, but decisions about venting, roof and structure colors, the installation of fans and even a bit more quality time in the basement can all add up to reduce the cost of air conditioning and give us some ideas about how to stay cool.
What tips would you add to our list? Share your ideas in the section below: