As the world gets hotter, air conditioners are becoming more important than ever.
They help people stay safe during heat waves and can even save lives. But experts say relying only on air conditioning is not a long-term solution.
Instead, they believe buildings should be designed to stay cooler naturally, reducing the need for air conditioners in the first place.
This is the message from a new review led by Professor Mat Santamouris from UNSW Sydney, published in Nature Reviews Clean Technology. The study looks at new ways to keep buildings cool while using much less electricity.
Air conditioning has become one of the biggest users of electricity around the world. Today, cooling accounts for almost 10% of global electricity use.
Around 10 new air conditioners are sold every second, and by 2050, experts expect there will be nearly 5.6 billion residential air-conditioning units worldwide.
While air conditioners protect people during extreme heat, they also create new problems. They use large amounts of electricity, which can overload power grids during heat waves.
In many countries, electricity is still generated using fossil fuels, meaning more air conditioning can also increase greenhouse gas emissions.
In addition, air conditioners release heat outdoors, making cities even hotter. This is known as the “urban heat island” effect.
Professor Santamouris says air conditioning will continue to play an important role, especially during dangerous heat events. However, he believes buildings should first be designed to stop heat from entering, so air conditioners do not have to work as hard.
One of the best ways to cool a building is through passive cooling. This means using building design and materials instead of electricity to lower indoor temperatures.
For example, adding shade around buildings, using highly reflective roofs and walls, improving natural ventilation, and installing special materials that release heat back into the atmosphere can all help keep indoor spaces cooler.
The review also highlights new technologies that could make passive cooling even more effective. These include advanced cooling coatings, smart shading systems, materials that combine different cooling methods, and personalized ventilation systems that direct cool air only where it is needed.
According to the researchers, combining these techniques with good building design could reduce the need for air conditioning by as much as 80% in hot climates. This would lower electricity use, reduce energy costs, and place less pressure on power networks during extreme weather.
Passive cooling can also make communities safer. During power outages caused by storms or heat waves, buildings that stay naturally cool can better protect the people inside. This is especially important for older adults, young children, and people with health conditions who are more vulnerable to extreme heat.
The researchers say future buildings should be designed for the warmer climate expected in coming decades, not for the climate of the past.
They also encourage governments to strengthen building standards, support climate-friendly building designs, and improve access to affordable cooling for lower-income families.
The researchers believe the best solution is not to replace air conditioning, but to combine efficient cooling systems with smarter building design. By keeping buildings naturally cooler, cities can become healthier, more comfortable, and better prepared for a hotter future while using far less energy.
