It's getting hotter and hotter on Earth. More and more people are using air conditioning to cool down. Large cities in particular are real heat islands. But air conditioning systems consume a lot of energy and harm the climate. Are there alternatives?
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00:00 Take a look at these building facades in Singapore.
00:03 And these in New Delhi, New York and Hong Kong.
00:07 Notice anything?
00:09 In these parts of the world, life without air conditioning can be uncomfortable or downright dangerous.
00:14 More than a dozen people have died in India in the past two months due to a severe heat wave.
00:19 A fierce heat wave.
00:20 Heat wave.
00:21 Heat wave.
00:22 But that brings us to our dilemma.
00:24 The technology needs lots of energy.
00:26 In fact, cooling building accounts for 10% of our global electricity consumption.
00:31 And that's bad news for global warming.
00:33 It's a vicious loop.
00:35 We cool the indoors, but we warm the outdoors.
00:38 Therefore generating the need for more cooling.
00:41 But there are solutions, some traditional, some modern, that don't eat up massive amounts of energy.
00:47 Nowadays, Americans are still some of the most prolific AC users globally.
00:54 90% of US households own an air conditioner.
00:58 In some of the hottest parts of the world, it's not even 10%.
01:02 But other countries want to catch up.
01:05 Just look how much more energy some of these emerging economies are projected to use in the coming decades to cool their homes and buildings.
01:12 If you see India's air conditioning market, it is growing in double digits.
01:17 Ankit Kalanki is working to open up the global market for high-efficiency air conditioners.
01:23 India's population is growing.
01:26 India is getting even hotter.
01:28 But also a large portion of Indian population is urbanizing, is moving to cities.
01:33 And all of that together constitutes a huge demand for air conditioners.
01:38 Because of trends like these, global energy demand for space cooling is projected to triple by 2050.
01:45 The question is how to meet the soaring demand without exacerbating the heat.
01:49 You may have heard of the urban heat island effect.
01:52 It's when urban areas like these get warmer than their surroundings, because all this concrete absorbs and retains heat.
01:59 And there's also lots of waste heat from human activities like transport or, well, air conditioning.
02:04 Creating more spaces with shady trees and other plants lessens this effect.
02:09 Like here in Berlin.
02:11 The Colombian city of Medellin was able to reduce average temperatures by 2 degrees Celsius only three years after planting green corridors.
02:21 The interconnected network of greenery spans dozens of waterways and busy polluted streets.
02:26 And minimizing heat expelled by cars also makes a difference.
02:33 In Spain, Barcelona's superblocks prioritize pedestrians and cyclists.
02:38 But scale matters.
02:40 The city's Institute for Global Health estimates that 117 heat-related deaths could be avoided every year if hundreds more blocks were introduced.
02:49 The next step is designing buildings that aren't as reliant on air conditioners.
02:53 And this is where we can really learn from traditional architecture.
02:57 Before technology, all people around the world found solutions to survive properly.
03:05 Charles Galavardin leads bioclimatic architecture projects in countries like Vietnam and Mauritania.
03:11 That means that designs take local climates into account.
03:15 So we have to study carefully all this vernacular architecture.
03:19 Some modern buildings are already doing this.
03:22 Such as Qatar University, which uses wind towers to keep its buildings cool.
03:26 This method has been used in Iran and other Middle Eastern countries for centuries.
03:31 The so-called wind catchers are designed to trap fresh air and direct it indoors.
03:36 The hot air gets pushed out.
03:38 You may also have noticed that houses in hot climates are often white.
03:42 Some countries like India are bringing back this approach by painting roofs with lime-based whitewash, which absorbs less heat.
03:48 This can reduce indoor temperatures by 2 to 5 degrees Celsius.
03:52 When designing new buildings, bioclimatic architects tend to combine different sources of inspiration.
03:58 But they will all tell you, location is everything.
04:02 You have to pay attention to the sun orientation.
04:06 And make sure your facades are not exposed to the direct sun.
04:11 And then we usually study carefully the wind direction.
04:16 Knowing the wind direction is important to design openings that encourage cross ventilation.
04:21 Other features that can help stave off heat are shading devices that keep the facade cool.
04:26 And insulation prevents heat from traveling through your roof, for example.
04:30 Galavardin says these methods can reduce indoor temperatures by about 5 degrees Celsius.
04:35 While ceiling fans can help circulate this cooler air.
04:39 ACs may still need to be used sometimes, but to a much lesser extent.
04:43 The problem? In many countries going through a construction boom, new buildings often look like this.
04:49 Builders tend to build them with floor-to-ceiling glass.
04:54 And that's a real problem because every time you put glass into a building, you turn it basically into a hot box.
05:02 It's like a solar cooker.
05:05 Architects and engineers say this aesthetic is popular because it's perceived as sleek, modern and lets in natural light.
05:11 Changing that would require more rigorous building regulations around energy efficiency.
05:16 And a massive cultural shift to actually get them enforced on the ground.
05:20 In most of the architecture schools, we are not trained for this.
05:26 When you ingrain that into their business as usual approach, you will get the solutions.
05:32 Another big obstacle is that this approach tackles new constructions.
05:36 But what about all the old, badly insulated buildings that already exist?
05:40 This takes us to our next solution. More efficient air conditioning.
05:44 Because there is no technological reason for ACs to use as much energy as many commercial models do now.
05:51 The AC industry is rooted in a roughly 100-year-old technology.
05:57 It's been working, convenient, you know, at the switch of a button we get cooling.
06:03 This is Neha Satcher. She works to make climate-friendly cooling more accessible.
06:08 There hasn't been a lot of motivation or market factors that have spurred innovation.
06:17 And you really see how wasteful ACs can be in places like India, Singapore or parts of the US.
06:23 Because this is where it often gets humid.
06:26 About a third of the energy is used for managing humidity.
06:31 While some modern models have a so-called dry mode to target humidity,
06:36 Kalanki says air conditioners are still pretty bad at measuring how much moisture is in the air.
06:41 And consequently, how much moisture they need to remove for optimum comfort.
06:45 So, many people simply blast their ACs to overcool the room and get humidity down to a desired level.
06:53 But what if we thought about efficient mechanical cooling on a much larger scale?
06:57 A system like this is already functioning in Singapore.
07:00 Here, an underground air conditioner touted as the largest in the world
07:04 cools residential buildings, banks, malls and this iconic hotel.
07:09 The technology is called district cooling and it can save up to 50% on energy and emissions.
07:16 That's because having one big plant cooling an entire district makes it super efficient.
07:22 The water is chilled 25 meters below the ground before it's piped across different buildings.
07:26 The challenge for district cooling is in terms of infrastructure.
07:32 It's a big capital investment and it requires a lot of infrastructure.
07:39 This may sound utopian, but like all other solutions, it requires lots of upfront capital, know-how and of course, awareness.
07:48 awareness.
07:48 (upbeat music)