You know, Herman, as I was walking up the hill to our place this afternoon, I could actually feel the heat radiating off the stone walls of the buildings. Jerusalem has this specific kind of dry heat that just settles into the architecture, and by three in the afternoon, the city feels like it is slowly breathing out all the energy it soaked up from the sun. It made me realize just how much we take that little hum in the background for granted.
The hum of the air conditioner. It is the unsung hero of the modern world, Corn. And honestly, it is the only reason we are able to sit here comfortably and record this. I am Herman Poppleberry, by the way, for anyone joining us for the first time. And yeah, that feeling of the city breathing heat is exactly why our housemate Daniel sent us this prompt. He has been thinking a lot about our recent episodes on air quality, and it led him down a rabbit hole regarding the sheer energy cost of keeping our indoor spaces livable.
It is a fascinating paradox, right? We use energy to move heat from inside to outside, which contributes to the warming of the outside environment, which then requires more energy to keep the inside cool. Daniel was asking about the current state of this technology and whether we can ever break that cycle. He wants to know if air conditioning can ever be truly sustainable, or if we are just fighting a losing battle against thermodynamics.
It is a big question. And honestly, it is one of the most important technical challenges of the twenty-first century. If you look at the projections from the International Energy Agency, the number of air conditioning units globally is expected to reach five point six billion by the year twenty-fifty. We are talking about ten new units being sold every single second for the next thirty years. In countries like Israel, it is a necessity, but as more of the world develops and temperatures rise, it becomes a global requirement for productivity and health. The United Nations Environment Programme just released their Global Cooling Watch report at COP thirty in Brazil, and the numbers are staggering. Global cooling capacity is projected to triple by twenty-fifty, and if we do not change the technology, emissions from cooling could rise to seven point two gigatons.
That is an incredible amount of pressure on the planet. And before we get into the heavy technical disruptions, I want to stick with the basics for a second. Most people, myself included, usually just think about the thermostat. We set it to twenty-three or twenty-four degrees and call it a day. But Daniel asked about what we can do beyond just changing the temperature setting. What is the actual state of efficiency in the units we have right now?
Well, the biggest shift in recent years, which many people might have in their homes without even realizing it, is the move from traditional compressors to inverter technology. In the old days, an air conditioner was either on or off. It was like a car that only had two settings: stopped or floor it. When the room got too warm, the compressor would kick on at full blast, consume a massive spike of electricity, cool the room down past the target, and then shut off.
I remember those. You could hear the loud clunk and the lights would flicker for a split second when it started up.
Exactly. That is incredibly inefficient. Modern inverter systems are more like a dimmer switch or a variable speed gas pedal. They can slow down or speed up the compressor to maintain a constant temperature. This reduces the energy load significantly because you are not constantly dealing with those high-current startup spikes. We are seeing units now with seasonal energy efficiency ratios, or SEER two ratings, that are double what they were twenty years ago. In fact, the average new unit sold today is about fifty percent more efficient than the global average stock, but we are still far from the theoretical maximum.
So if someone is looking at their current setup, making sure they have an inverter-driven system is the first major step. But what about maintenance? We always hear about cleaning filters, but does that actually move the needle on electricity consumption?
Oh, it moves the needle more than you would think. A dirty filter or a clogged outdoor condenser coil can drop efficiency by fifteen to twenty-five percent. Think about it this way: your air conditioner is essentially a heat exchanger. It is trying to move heat from your indoor air into a refrigerant, and then move that heat from the refrigerant into the outdoor air. If the coils are covered in dust or grime, you are basically wrapping your heat exchanger in a blanket. The fans have to work harder, the compressor has to run longer, and you are paying for energy that is just being wasted as friction and heat within the machine itself. Also, people forget the condensate drain. If that gets clogged with biofilm, it can lead to humidity issues and mold, which makes the air feel warmer than it actually is, leading you to turn the temperature down even further.
That makes sense. It is like trying to run a marathon while breathing through a straw. But let's look at the bigger picture. Even with a clean filter and an inverter, we are still using a huge amount of power. In episode one hundred ninety, we talked about white-labeling and how many global brands are actually using the same internal components. Does that mean we have hit a ceiling? Is there a limit to how efficient a standard vapor-compression cycle can be?
We are definitely approaching the theoretical limits of the vapor-compression cycle, which is the technology Willis Carrier pioneered back in nineteen hundred and two. It relies on the physics of phase changes, boiling and condensing a refrigerant. While we have gotten very good at it, we are still fighting the laws of physics. One of the biggest issues isn't just the electricity, but the refrigerants themselves. We are currently in the middle of a massive global transition mandated by the Kigali Amendment to the Montreal Protocol.
Right, the gases inside the coils. We moved away from the old chlorofluorocarbons because they were eating the ozone layer, but the replacements, the hydrofluorocarbons, are still potent greenhouse gases if they leak, aren't they?
They are thousands of times more potent than carbon dioxide. As of late twenty-twenty-five, over one hundred and seventy countries have ratified the Kigali Amendment, which requires a gradual phase-down of these HFCs. In the United States, the Environmental Protection Agency has been issuing new rules for twenty-twenty-six that strictly limit the production of high global warming potential refrigerants. We are transitioning to what we call low GWP alternatives. For example, R-thirty-two is becoming the standard for residential units, and some companies are even looking back at natural refrigerants like propane, which is R-two-ninety, or even carbon dioxide itself. It sounds counterintuitive to use carbon dioxide as a refrigerant to fight climate change, but compared to the synthetic gases we have been using, its impact is negligible if it leaks.
That is an interesting shift. But let's talk about the sustainability aspect Daniel mentioned. Can we ever get to a point where cooling isn't a net drain on the planet? I am thinking about our discussion in episode one hundred fifty-nine regarding impact accounting. If we account for the full lifecycle and the grid load, is sustainable AC even possible?
It is possible, but it requires us to stop thinking about the air conditioner as an isolated box on the wall. True sustainability comes from the intersection of the machine, the building envelope, and the energy grid. One of the most effective ways to make AC sustainable is to reduce the load it has to carry in the first place. This means better insulation, smart windows that reflect infrared heat but let in visible light, and even passive cooling techniques. But the real game-changers are the disruptive technologies that are finally moving out of the lab and into commercial reality here in twenty-twenty-six.
What are the technological disruptions that could actually replace the traditional compressor? You mentioned some exciting things before we started recording.
This is where it gets really exciting, Corn. One of the biggest breakthroughs is membrane-based cooling. Companies like Blue Frontier and Transaera have fundamentally redesigned how we handle humidity. You see, in a traditional AC, about half the energy is spent just on dehumidification. To get the water out of the air, the machine has to cool the air down below the dew point, which is often much colder than you actually want the room to be. Then it has to blow that super-chilled air into the room where it mixes with warmer air. You are spending a huge amount of energy just to squeeze the water out of the air.
I have noticed that. Sometimes the air coming out of the vent feels icy, even if the room is still twenty-five degrees.
Exactly. Blue Frontier has developed what they call the Energy Storing and Efficient Air Conditioner, or ESEAC. It uses a liquid desiccant, essentially a salt solution, to pull the humidity out of the air before it ever hits the cooling coils. By separating the cooling of the air from the dehumidification, they can reduce energy consumption by fifty to ninety percent. And because the desiccant can be recharged and stored, the unit acts like a thermal battery. It can do the heavy lifting when electricity is cheap or renewable energy is peaking, and then provide cooling later without needing the compressor to run at full blast.
That sounds like a massive win for places like Singapore or the American South where humidity is the real killer. What about other materials? I have heard people talking about sponges for air.
That is likely Transaera. They use metal-organic frameworks, or MOFs. These are highly porous materials that have more surface area per gram than almost anything else on Earth. They act like a molecular sponge to grab water vapor. They can be regenerated using the low-grade waste heat that the air conditioner itself produces. It is a plug-and-play solution that can be swapped into existing commercial systems to cut energy use by forty percent immediately. We are seeing the first large-scale rollouts of these in commercial buildings this year.
That is incredible. But what about the cooling itself? Is there a way to cool things down without using any electricity at all? It sounds impossible, but I have been reading about something called radiative sky cooling.
It sounds like magic, but it is pure physics. There is a company called SkyCool Systems that has commercialized panels using a multilayer optical film. These panels are designed to reflect almost all incoming sunlight while simultaneously emitting heat in a very specific infrared spectrum. This spectrum, between eight and thirteen micrometers, happens to be a window where our atmosphere is transparent. So, the heat from the panel travels straight through the atmosphere and out into the cold vacuum of deep space.
Wait, so we are literally beaming our heat into space?
Precisely. These panels can stay five to ten degrees cooler than the ambient air even under direct sunlight. You can integrate them as a retrofit to existing AC systems to pre-cool the refrigerant or the water in a chiller. In field tests at supermarkets in California, they have seen energy savings of fifteen to forty percent with zero additional electricity input for the cooling effect itself. It is essentially using the universe as a giant heat sink.
That is mind-blowing. And then there is the solid-state stuff you mentioned. No moving parts at all?
Right. This is the caloric effect. We are seeing a lot of movement in magnetocaloric and electrocaloric cooling. Instead of a gas, you use a solid material that changes temperature when you apply a magnetic or electric field to it. The Thermag twenty-twenty-six conference in Slovenia this June is expected to showcase the first residential-scale prototypes. Magnetocaloric systems can be thirty to fifty percent more efficient than vapor-compression because they do not have the same mechanical losses. They are silent, they use no harmful refrigerants, and they are incredibly compact. We are likely still a few years away from seeing these at your local hardware store, but the materials science is finally catching up to the theory.
It feels like the future of AC is less about a better box on the wall and more about a smarter system for the whole building or city. But I want to go back to Daniel's question about the grid. Even if the units are fifty percent more efficient, if everyone starts using them, we are still putting a massive strain on the power plants. How do we manage that?
That is the second-order effect. The timing of AC use is what kills the grid. This creates the duck curve in energy demand. To make AC sustainable, we need thermal energy storage. We are seeing a rise in ice storage and salt hydrate systems. Imagine a system that runs at night when the outside temperature is lower and electricity is cheaper. It freezes a tank of phase-change material. Then, during the peak of the day, the system just circulates your indoor air over that chilled material. You are shifting the load. This is becoming a key part of virtual power plants, where the grid can actually communicate with your AC to manage demand in real-time.
We actually talked about something similar in episode one hundred ninety-nine when we were discussing AI and weather forecasting. If the system knows a heatwave is coming, it could pre-cool the thermal storage the night before. But what about the buildings themselves? I feel like we have forgotten how to build for the heat.
I couldn't agree more. In Jerusalem, the old stone houses with thick walls are incredibly cool in the summer without any AC at all. We've traded that passive efficiency for the convenience of modern glass-box construction. But we are seeing a return to bioclimatic design. In Singapore, they have the Go twenty-five campaign, encouraging people to set their thermostats to twenty-five degrees or higher. In Taipei, businesses can actually be fined now if they cool their rooms below twenty-six degrees. We are realizing that the most sustainable AC is the one that doesn't have to work as hard because the building is helping it out.
So, to answer Daniel's question: is sustainable AC possible? It sounds like the answer is yes, but it won't look like the AC we have today. It will be a combination of solid-state tech, moisture-removing membranes, radiative panels, and buildings that are designed to work with the environment rather than against it.
And probably a lot more thermal batteries in our basements. I really believe the shift from cooling the air to managing the heat is where the breakthrough happens. It is a subtle difference in perspective, but it changes everything about how we design our cities. We have to move away from the Jevons Paradox, where making things more efficient just leads us to use them more. We need a fundamental shift in our relationship with indoor climate.
This has been a deep dive I didn't know I needed today, Herman. It is easy to just complain about the heat, but understanding the sheer mechanical and physical effort going into keeping us cool makes me appreciate that hum a bit more. It is a marvel of engineering, honestly. We are literally defying the natural flow of energy every single day.
We really are. And thanks to Daniel for the prompt. It is exactly the kind of technical-meets-existential question we love here.
Well, if you have been listening and you have thoughts on how you stay cool or if you have seen some of these new technologies like SkyCool or Blue Frontier in action, we would love to hear from you. You can find us at our website, myweirdprompts.com, where we have the full archive of all four hundred twenty-two episodes now.
And if you're enjoying the show, we'd really appreciate a quick review on your podcast app or a rating on Spotify. It genuinely helps other people find these deep dives and keeps us going.
Definitely. We've been doing this for a long time, and the community of listeners who send in these prompts is really what makes the show special. We will be back next week with another exploration. Stay cool out there.
Until next time!
