As temperatures soar across parts of the southern US, smashing heat records, it may be tempting to reach for the air conditioner and turn it up to max.
However, a group of researchers from the UK warn air con units are both power hungry and operate using gasses that can add to the greenhouse effect if they leak into the air.
The team suggest three alternative solutions to cool your home — including blocking the sun, taking advantage of natural ventilation and using fans, which are less energy-intensive.
And if air con is unavoidable, the researchers said, it can help to pick units with a high-efficiency rating, and that use less potentially harmful refrigerants.
The former can be assessed using the so-called energy efficiency ration, the team explained, with the best unit being those with a rating near or above four.
Writing in the Conversation, Dr Jesus Lizana, Dr Nicole Miranda and Professor Radhika Khosla of the University of Oxford said: “Air conditioners often become the default solution when temperatures rise as they provide fast and effective relief from scorching heat.
“But air conditioners also consume a lot of energy. Many also use refrigerants called fluorinated gasses that have high global warming potential when they leak.
“Unrestrained usage of air conditioners in the future will result in increased emissions and further global warming.
“So, it’s important to know the recommended steps to keep your home cool in the face of rising temperatures, without causing the climate more harm.”
The first of the team’s suggestions for cooling your home without air conditioning involves blocking the sun’s rays from reaching the inside of the building in the first place.
The team said: “There are different ways to achieve this, ranging from reflective and ventilated roofs to external window shutters and awnings.
“Research one of us worked on in Spain found that using external window shutters can reduce cooling needs by up to 14 percent.”
One traditional approach for cooling involves just painting your roof in a light color to reflect the sunlight back.
In fact, the team noted, researchers in Pakistan found that this approach can reduce cooling needs by more than seven percent in some of the country’s hottest cities.
The team added: “Another effective technique is to make use of the shade provided by tree canopies. Research in Melbourne, Australia, has shown that trees covering buildings in shade can lower the surface temperature of walls by up to 9C [16.2F].”
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We are all familiar with how opening windows after the outside temperature has dropped can help to cool down poorly-ventilated buildings by letting warm air escape and cooler air in.
However, Dr Lizana and his colleagues note, incorporating features like ventilation chimneys and roof vents into new building designs can increase the rate of airflow.
They said: “These features are often found in hot and arid climates, particularly in the Middle East.
“Historically, buildings in this region made use of tall, chimney-like structures called wind catchers that capture cool prevailing winds and redirect them into homes.”
Another strategy is “cross-ventilation”, in which a fresh breeze is allowed to enter a building through one opening and exit through another on the opposite side.
The team added: “If necessary, this can be promoted by incorporating inner courtyards — a design that has been used for centuries in warmer climates to keep buildings cool.
“Our previous research found that inner courtyards can reduce the total amount of time in which we need to take measures to cool down — known as ‘indoor discomfort hours’ by 26 percent.”
Our perception of coolness, the team noted, is also not solely based on the actual temperature — and so by tackling factors like humidity and air speed, we can also make ourselves feel more comfortable.
The researchers wrote: “That’s where fans come in handy, whether they’re on the ceiling or standing on their own.
“By combining fans with air conditioning, it’s possible to raise the thermostat setting from 24C [75.2F] to 27C [80.6F] and still feel cool.
“This simple adjustment can reduce household energy consumption for cooling by more than 20 percent.”
Another issue with centralized air conditioning systems is that they often end up cooling us down more than is necessary — or even waste energy cooling unoccupied rooms.
To mitigate this, people can select lower air con settings and then bring in smaller-scale cooling solutions like desk fans, cooled seats, or personal cooling devices.
The trio concluded: “The key is to find solutions that work well together and can be adapted easily so that the cost of installing energy-intensive air conditioning systems can be avoided or reduced.
“This approach will allow people to stay comfortable during hotter temperatures, without compromising the climate further for future generations.”