WUFT | News and public media for north central Florida
Ancient roots, modern solutions
By Nathan Thomas
April 14, 2025 at 4:00 AM EDT
Modern air conditioning is a necessity, but it’s also a growing problem. Can Indigenous architecture and passive cooling methods help break the cycle?
In the thirteenth century, Marco Polo traveled to Iran, then Persia, to the city of Hormuz. Hormuz was a metropolis of the time, with a busy port, palaces and fortresses, wide streets, and bazaars.
“The weather in Hormuz is too hot and intolerable,” he proclaimed. “Therefore, its residents have the tools like the fan which brings the air flow from the outside into the house.”
He was referring to windcatchers, elegant, latticed structures atop roofs that used air’s density to suck cool breezes into buildings while expelling hot air. The windcatchers were divided into compartments with vertical slats to strategically direct air flow.
The structures Marco Polo witnessed in Hormuz have been used for millennia across the world to regulate temperature in structures from Arizona to the United Kingdom.
Lessons from Indigenous design are a crucial part of the solution in addressing the problems modern air conditioners pose to the environment and us.
Modern Windcatchers in the UK. (Courtesy Monodraught, a sustainable cooling company in the United Kingdom)<br/> (2100x1500, AR: 1.4)
Six percent of U.S. energy consumption is spent on air conditioning. But in Florida, the hottest state in the nation, that percentage doubles—12 percent of our energy use goes to AC. That amounts to 27 million metric tons of carbon dioxide a year from Florida AC alone, more than the entire country of Lebanon.
Demand is expected to grow as the world warms, creating a vicious cycle: The more air conditioners run, the more emissions are released into the atmosphere, creating more warming.
Adapt Building Design to the Local Environment
Part of the solution to this paradox, experts say, is to borrow from historic cooling techniques that adapted building design to local climates—which helps avoid excessive power draw in the first place.
On the Hopi Reservation in northeastern Arizona, Dr. Michael Kotutwa Johnson has lived comfortably without air conditioning for decades. He lives off-grid in a traditionally built home that uses the design of the structure to cool and heat the air naturally.
That high-altitude desert is subject to extreme temperature differentials throughout the year. In summer, averages can reach the nineties. During winter nights, it can drop into the teens. Yet Johnson maintains his home at a relatively constant temperature thanks to design.
His home has low ceilings and is built two feet into the earth, with some walls up to six feet thick to insulate against the cold.
“It’s an all-stone structure in there, so rather than relying on particle board or drywall or some synthetic material like that, we just use natural materials and as we add to these traditional homes, we re-use the stones,” he says.
These principles reflect a broader critique of modern construction methods, according to Hal Knowles, a University of Florida professor of sustainability and the built environment.
Michael Kotutwa Johnson’s home ventilation system in northeastern Arizona. (Courtesy Michael Kotutwa Johnson) (1106x1728, AR: 0.6400462962962963)
"We try to solve these problems by throwing more energy at it. Solving it with force on the back end, rather than with elegance and grace on the front end,” he says.
In the summer, Johnson relies on something very similar in purpose to the wind catchers Marco Polo witnessed in Iran to keep his home cool.
“As soon as that temperature gets to a certain degree in the winter time, or when it gets too hot, then that vent starts pulling air down the shaft and out up against that stone which blows it back up out of the opening on the roof.”
Because Johnson doesn't have central AC, not all the rooms in his house are the same temperature. He estimates, however, that in the heat, his home is twenty degrees or more cooler than outside. If one room is too hot to sleep in, he simply moves to one with a preferable temperature.
With Phoenix’s average monthly electric bill pushing upwards of $250 dollars a month, Johnson said, he saves thousands of dollars a year relying on Indigenous design principles to cool and heat his home.
“There’s nothing better than building out of the earth,” he says. “That’s what I believe in.”
Make active systems sustainable
Generally, architects split cooling systems into two areas, active and passive. Passive systems, such as wind catchers or Johnson’s vents, do not require energy to cool. Active systems, like AC or heat pumps, rely on energy.
UF architecture professor Martin Gold says the most efficient active cooling and heating system today is probably the geothermal heat pump. These pumps transfer heat to and from the earth, which maintains a constant temperature of 72 F year-round in Florida, making it an ideal medium for energy exchange.
“It’s a lot easier to put the heat into 72 degrees than it is to put it into 95 degrees,” Gold explains.
A reservoir in Iran's Isfahan province uses a large wind catcher to cool water. (Mohammadjavad Ebrahimi, Creative Commons) (1704x2272, AR: 0.75)
Bahar Armaghani, Director of Sustainability and the Built Environment at UF, stresses that affordability is no longer a barrier to renewable energy adoption. “If somebody’s talking to you about sustainability and they don't have the economic case, they’re doing the whole program an injustice,” she said.
The cost of solar, wind, and batteries has dropped by an estimated 10% annually.
How do we get it done?
Armaghani says local governments will be key to adoption of renewables on a broader scale. Local officials have the means to amend their codes, revise their standards, and offer incentives to developers. Pressure from citizens can help give them the will.
“Those sustainability approaches, most of them are voluntary, but once you make it part of the jurisdiction for permitting, for getting the certificate of occupancy, for reviewing their design, it’s really helpful,” Armaghani says.
Gainesville has already started taking these steps by requiring developers to save trees from destruction in their plans and paying into a Tree Mitigation Fund, which is used to protect and expand Gainesville’s famous tree canopy.
Trees are an incredibly valuable passive system for reducing the load on air conditioners, says Sam Schatz, program coordinator for Gainesville’s Urban Forestry division.
A bird's-eye view of Gainesville's tree canopy. The more trees, the lower the electric bills, says Sam Schatz, program coordinator for Gainesville's Urban Forestry Division. (Rylan DiGiacomo-Rapp/WUFT News) (5184x3456, AR: 1.5)
“If you put a tree in between where the sun is shining and your home, that tree is now casting shade and protecting your home from that sun,” he says, “Now, it takes much less energy for your air conditioner to turn on and cool your house. If you have your house set to 78—which I hope all of you do—it’s only going to take a little bit of energy to keep it at that 78 versus if the sun is heating your home all the way to 85 every day.”
Especially in years when federal and state governments may not champion environmental concerns, local government is the engine that can drive lasting change.
“If there’s a lot of people that are asking for more trees or better care of the trees, going to your City Commission, likely something’s going to happen,” Schatz says. “All they have to do is talk to one of our city leaders, and they don’t even ask how high, they just jump.”
Cooling our homes and cities is not just a technological challenge—it’s an opportunity to rethink how we build and live in harmony with our environment.
More than that, it’s something that every resident of every city can get involved in. Whether by planting trees to create natural cooling, advocating for local green policies, or attending a city meeting to support sustainable initiatives, there’s no barrier to entry—all you have to do is show up and make your voice heard.
By integrating the wisdom of ancient design and cutting-edge technologies, we can create spaces that are both comfortable and ecologically responsible—redefining comfort without compromising the planet.
“The weather in Hormuz is too hot and intolerable,” he proclaimed. “Therefore, its residents have the tools like the fan which brings the air flow from the outside into the house.”
He was referring to windcatchers, elegant, latticed structures atop roofs that used air’s density to suck cool breezes into buildings while expelling hot air. The windcatchers were divided into compartments with vertical slats to strategically direct air flow.
The structures Marco Polo witnessed in Hormuz have been used for millennia across the world to regulate temperature in structures from Arizona to the United Kingdom.
Lessons from Indigenous design are a crucial part of the solution in addressing the problems modern air conditioners pose to the environment and us.
Modern Windcatchers in the UK. (Courtesy Monodraught, a sustainable cooling company in the United Kingdom)<br/> (2100x1500, AR: 1.4)
Six percent of U.S. energy consumption is spent on air conditioning. But in Florida, the hottest state in the nation, that percentage doubles—12 percent of our energy use goes to AC. That amounts to 27 million metric tons of carbon dioxide a year from Florida AC alone, more than the entire country of Lebanon.
Demand is expected to grow as the world warms, creating a vicious cycle: The more air conditioners run, the more emissions are released into the atmosphere, creating more warming.
Adapt Building Design to the Local Environment
Part of the solution to this paradox, experts say, is to borrow from historic cooling techniques that adapted building design to local climates—which helps avoid excessive power draw in the first place.
On the Hopi Reservation in northeastern Arizona, Dr. Michael Kotutwa Johnson has lived comfortably without air conditioning for decades. He lives off-grid in a traditionally built home that uses the design of the structure to cool and heat the air naturally.
That high-altitude desert is subject to extreme temperature differentials throughout the year. In summer, averages can reach the nineties. During winter nights, it can drop into the teens. Yet Johnson maintains his home at a relatively constant temperature thanks to design.
His home has low ceilings and is built two feet into the earth, with some walls up to six feet thick to insulate against the cold.
“It’s an all-stone structure in there, so rather than relying on particle board or drywall or some synthetic material like that, we just use natural materials and as we add to these traditional homes, we re-use the stones,” he says.
These principles reflect a broader critique of modern construction methods, according to Hal Knowles, a University of Florida professor of sustainability and the built environment.
Michael Kotutwa Johnson’s home ventilation system in northeastern Arizona. (Courtesy Michael Kotutwa Johnson) (1106x1728, AR: 0.6400462962962963)
"We try to solve these problems by throwing more energy at it. Solving it with force on the back end, rather than with elegance and grace on the front end,” he says.
In the summer, Johnson relies on something very similar in purpose to the wind catchers Marco Polo witnessed in Iran to keep his home cool.
“As soon as that temperature gets to a certain degree in the winter time, or when it gets too hot, then that vent starts pulling air down the shaft and out up against that stone which blows it back up out of the opening on the roof.”
Because Johnson doesn't have central AC, not all the rooms in his house are the same temperature. He estimates, however, that in the heat, his home is twenty degrees or more cooler than outside. If one room is too hot to sleep in, he simply moves to one with a preferable temperature.
With Phoenix’s average monthly electric bill pushing upwards of $250 dollars a month, Johnson said, he saves thousands of dollars a year relying on Indigenous design principles to cool and heat his home.
“There’s nothing better than building out of the earth,” he says. “That’s what I believe in.”
Make active systems sustainable
Generally, architects split cooling systems into two areas, active and passive. Passive systems, such as wind catchers or Johnson’s vents, do not require energy to cool. Active systems, like AC or heat pumps, rely on energy.
UF architecture professor Martin Gold says the most efficient active cooling and heating system today is probably the geothermal heat pump. These pumps transfer heat to and from the earth, which maintains a constant temperature of 72 F year-round in Florida, making it an ideal medium for energy exchange.
“It’s a lot easier to put the heat into 72 degrees than it is to put it into 95 degrees,” Gold explains.
A reservoir in Iran's Isfahan province uses a large wind catcher to cool water. (Mohammadjavad Ebrahimi, Creative Commons) (1704x2272, AR: 0.75)
Bahar Armaghani, Director of Sustainability and the Built Environment at UF, stresses that affordability is no longer a barrier to renewable energy adoption. “If somebody’s talking to you about sustainability and they don't have the economic case, they’re doing the whole program an injustice,” she said.
The cost of solar, wind, and batteries has dropped by an estimated 10% annually.
How do we get it done?
Armaghani says local governments will be key to adoption of renewables on a broader scale. Local officials have the means to amend their codes, revise their standards, and offer incentives to developers. Pressure from citizens can help give them the will.
“Those sustainability approaches, most of them are voluntary, but once you make it part of the jurisdiction for permitting, for getting the certificate of occupancy, for reviewing their design, it’s really helpful,” Armaghani says.
Gainesville has already started taking these steps by requiring developers to save trees from destruction in their plans and paying into a Tree Mitigation Fund, which is used to protect and expand Gainesville’s famous tree canopy.
Trees are an incredibly valuable passive system for reducing the load on air conditioners, says Sam Schatz, program coordinator for Gainesville’s Urban Forestry division.
A bird's-eye view of Gainesville's tree canopy. The more trees, the lower the electric bills, says Sam Schatz, program coordinator for Gainesville's Urban Forestry Division. (Rylan DiGiacomo-Rapp/WUFT News) (5184x3456, AR: 1.5)
“If you put a tree in between where the sun is shining and your home, that tree is now casting shade and protecting your home from that sun,” he says, “Now, it takes much less energy for your air conditioner to turn on and cool your house. If you have your house set to 78—which I hope all of you do—it’s only going to take a little bit of energy to keep it at that 78 versus if the sun is heating your home all the way to 85 every day.”
Especially in years when federal and state governments may not champion environmental concerns, local government is the engine that can drive lasting change.
“If there’s a lot of people that are asking for more trees or better care of the trees, going to your City Commission, likely something’s going to happen,” Schatz says. “All they have to do is talk to one of our city leaders, and they don’t even ask how high, they just jump.”
Cooling our homes and cities is not just a technological challenge—it’s an opportunity to rethink how we build and live in harmony with our environment.
More than that, it’s something that every resident of every city can get involved in. Whether by planting trees to create natural cooling, advocating for local green policies, or attending a city meeting to support sustainable initiatives, there’s no barrier to entry—all you have to do is show up and make your voice heard.
By integrating the wisdom of ancient design and cutting-edge technologies, we can create spaces that are both comfortable and ecologically responsible—redefining comfort without compromising the planet.