You might have noticed that it’s kind of hot out there. And it’s only going to get worse: global demand for cooling is projected to triple by 2050. Finding a way to cool spaces and people without frying the planet is a crucial climate challenge. I’m joined by RMI’s Ankit Kalanki to unpack the hidden world of AC refrigerants and testing standards, the crucial distinction between lowering temperatures and dehumidifying, new AC technologies on the horizon, and the building and urban design changes that can take some of the pressure off.
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David Roberts
All right, everyone. Hello. This is Volts for June 24, 2026, “How to keep people cool without making the planet even hotter.” I’m your host, David Roberts.
Today, keeping ourselves and our products cool — air conditioning and refrigeration — produces around 7% of global greenhouse gas emissions, as much as global cement production. If the technology doesn’t substantially improve and growth continues, especially in emerging economies where AC ownership is climbing 10-15% a year, that share could nearly double by 2050. The IEA now projects AC electricity demand will grow faster than data center demand between now and 2030.
Cooling heats the climate in two ways. First, the refrigerants leaking out of ACs are powerful greenhouse gases, often thousands of times more potent than CO2. Second, the electricity to run them is already 17% of global power consumption, projected to triple by 2050, and a lamentable amount of that power still comes from fossil fuels.
In short, more cooling produces more warming, which raises demand for cooling, which produces more warming … it’s a bit of a doom loop.
Unlike many subjects we cover here on Volts, this is not primarily a tech innovation problem. Between more-efficient ACs and electricity decarbonization, we already have the technology to cut cooling emissions by something like 97% — no tech breakthroughs required. The trick is that getting there means a broad array of reforms, everything from rewriting how we test ACs to retooling manufacturing to upgrading buildings to redesigning cities for heat. It’s a lot.
To walk through it with me, I’m talking today with Ankit Kalanki, who leads RMI’s Global Cooling Efficiency Accelerator. We’re going to get into all of it — why current ACs are underperforming, what reforms could boost efficiency, new tech on the horizon, and the building and urban-design pieces that must be part of the answer. I’ve been meaning to get to this subject for a long time, so I’m excited to jump into it.
All right then, Ankit Kalanki, welcome to Volts. Thank you so much for coming.
Ankit Kalanki
Thank you, Dave. It’s a pleasure.
David Roberts
All right, we’ve got so much ground to cover here. I’m somewhat daunted, but I think the right place to start is just a very quick walkthrough of basic air conditioning technology. I was blown away as I was reading the history of this.
This guy, Willis Carrier — people will recognize that name, continues to be an air conditioning company to this day — patented this basic vapor compression process in 1902. The pieces of it have changed somewhat since then, but the basic architecture of how it works is still the same. We’re still using vapor compression technology. Maybe just start by walking briefly through what vapor compression technology is. How does it work? How do we cool spaces with this today?
Ankit Kalanki
Vapor compression technology works by moving heat from indoor spaces to outdoor spaces. That’s the fundamental of what cooling or air conditioning really is and what an air conditioner does. It’s not about making cold, but about moving the heat.
Air conditioner — think about it as a heat pump where you are moving heat from inside the rooms and dumping it outside. The working fluid that enables this is what we call a refrigerant. That refrigerant takes the heat from indoor spaces, evaporates, absorbs that heat. Then you have a technology called a compressor where that refrigerant gas gets compressed. Then you have the outdoor unit where that heat goes and gets rejected to the outdoor ambient and the cycle gets repeated — it’s a closed loop cycle. That’s how the vapor compression technology works. That’s how the air conditioner moves heat outside and keeps your indoor spaces cool.
David Roberts
That’s air conditioning of spaces for people. That’s refrigeration of coolers. That’s basically all cooling — you take the refrigerant, it evaporates and absorbs heat. Then you compress it, makes it super hot, goes outside and it condenses, which releases the heat. Then you reduce the pressure again, it goes back inside, does it all over again. This, as I said, is basically the same. These pieces — refrigerants have changed, compressors have changed somewhat and gotten more efficient and so on. But that basic cycle is still how air conditioners work today.
As you mentioned, we’re not going to get into this, but just as a side thing for my listeners, I’ve done many podcasts on heat pumps, and this is exactly the same way a heat pump works, just in reverse. A heat pump is just a reverse air conditioner, or an air conditioner is just a reverse heat pump, you could say.
Let’s then talk about the basic levers we can use to improve this process. These pieces — the refrigerant, the compressor, etc. How do you improve these pieces? Maybe we’ll just start with refrigerants because the history of refrigerants is quite interesting. There have been a lot of rounds of angst and replacement and then more angst and more replacements. Tell us a little bit about how refrigerants have evolved.
Ankit Kalanki
You said it. It’s a closed loop with refrigerants, where the full circle is getting completed again. When we first used any form of cooling or mechanical cooling, it was based on natural refrigerants. Carbon dioxide, ammonia were used as refrigerants very early when we wanted cooling and refrigeration. Then we evolved to synthetic refrigerants, which were called chlorofluorocarbons because they were more efficient in doing the same thing or providing cooling and refrigeration. But while doing so, they were causing a very big problem — a hole in the ozone layer.
Because of that, you had the Montreal Protocol treaty that decided to phase down and ultimately phase out all these chlorofluorocarbon refrigerant gases. That made way for hydrofluorochlorocarbons, which we call HFCs, that are widely used today — introduced because they had zero ozone-depleting potential, or ODP. That was a way at that time for solving the problem of the hole in the ozone layer. But as these HFCs became more and more common and widely adopted, we all realized that these are now very high-potent greenhouse gases that have on average 2,000 times more global warming potential than carbon dioxide. If they get released into the environment, it could be a climate catastrophe.
David Roberts
They’re not released into the environment from an air conditioner that’s working properly. They leak in manufacturing, transport, units that aren’t working correctly. These are all leaks we’re talking about. But there are hundreds of millions of these units around. All these small leaks of highly potent greenhouse gases really add up.
Ankit Kalanki
Precisely. I say that refrigerant inside a closed system is totally fine as long as it doesn’t leak, because it’s giving you the cooling that you need and the refrigeration that you need, and it’s allowing you to do it in a very efficient way. But it’s through that operating lifetime when the system gets serviced by a contractor that comes to your place and then they play with the system. Over a period of time, due to the corrosive nature of the environment or other ambient factors, the system might develop some issues — like the coil gets corroded and then you have some leaks in the system.
David Roberts
And disposal too, right?
Ankit Kalanki
Yes, exactly. I was going to come to that. End of life is another problem where, despite — in the United States, for example — refrigerant venting is legally banned, there is very limited refrigerant recovery that happens at the end of life. You end up in a system or in a loop where a lot of that refrigerant ends up getting leaked into the environment at the end of life as well, which is the problem.
David Roberts
Now we’re trying to move past HFCs too.
Ankit Kalanki
Yes, exactly. Now that the world has discovered and understood that the HFCs are also very highly potent greenhouse gases and are contributing to global warming significantly because they are also short-lived and significantly more potent, now we are going back to natural refrigerants. In many parts of the world we are looking at hydrocarbons — one of the refrigerants is propane, which is being used for air conditioning applications, which has a global warming potential of about 3. In industrial applications, ammonia continues to be a refrigerant of choice for many in grocery stores. In many industrial applications, carbon dioxide with a GWP of 1 is increasingly also getting adopted. We are heading towards where it all started — the world of natural refrigerants.
David Roberts
But the reason we moved off those natural refrigerants in the first place is ammonia is quite toxic, propane is quite flammable. There were trade-offs with these that led us away from them in the first place. Those are still problems. We have not yet found a refrigerant that is the magic, does all the things we want with none of the things we don’t want. We are now returning to some that are toxic and/or flammable.
Ankit Kalanki
We have not found any ideal refrigerant to date that checks all our boxes. Depending on the application, you can make what refrigerant works best. If it’s an environment where you have outdoor setups and large access to ambience, you can consider some of these natural refrigerants which have been used in many industrial applications for many decades now. It’s more about getting used to it with the right set of safety practices and adapting it and adopting it at scale.
David Roberts
Let’s also talk briefly about the other pieces then. Compressors — these are driven by electric motors. I guess all Volts listeners know electric motors have gotten more efficient over time. How have compressors improved?
Ankit Kalanki
The compressor, as everyone calls it, is the heart of the air conditioner or a heat pump technology. That is what makes the air conditioner deliver the cooling or the heating.
David Roberts
And that’s what’s consuming the electricity — everything else is plumbing.
Ankit Kalanki
That’s the majority of the power. The compressor dictates how much power, and more particularly peak demand, air conditioning and heat pump contribute. The industry on the compressor technology has evolved significantly over the last few decades. We used to have a lot of fixed-speed compressor technology, which means it’s only either on or off. Once you set a certain temperature on your thermostat or using a remote control on your air conditioner, your system will operate until it reaches that set point and then your technology will cut off. It was the technology that was commonly used for multiple decades.
Over the last decade or so, markets have evolved to what we call inverter technology, or in other terms, variable speed technology, where now you are not in the on and off situation only, but the compressor reduces its speed as you reach closer to your set point or the point that you have set on the threshold. There has been this innovation where you have this variable frequency drive or VFD that gets attached to your compressor and compressor motor technology, and it enables that adjustment of the speed based on how quickly and how much cooling or heating you want from the system.
When you look at that transition — if I give you an example, in India, the fixed speed market was almost 80% in 2015, and in 2025, it’s the opposite. 80% market is now inverter technology in the residential air conditioning sector. Japan is primarily inverter technology. China is again very high on inverter technology, close to 80, 90% as well. Most of the market has evolved and moved on to inverter technology. Now that’s an area where more innovation is needed as to how you can further improve the aspects of the variable speed technology.
David Roberts
The other piece is, I guess, heat exchangers have probably improved over time also. And the controls — talk a little bit about the software controls because as I understand it, that’s also a big piece of this.
Ankit Kalanki
That is, in my view, today’s biggest piece that needs to get solved for — that will significantly improve the efficiency of air conditioners — and it is tied to two pieces. One is what we need air conditioners for in real terms. Controls have a big role to play in that. Controls have a big role to play in how these air conditioners are tested and rated. Controls are the piece that connects both of them. I’ll come to the first part first.
You mentioned Willis Carrier and the history of air conditioning. Let me share this with the audience. Air conditioner technology in the first place was not invented to provide cold temperatures. It was meant to reduce humidity or remove the moisture from the air. Willis Carrier was working back in the day in a Brooklyn-based paper factory and he was constantly noticing the warping of the paper and it was disrupting the quality of the paper. That’s where the idea came from — what can we do to remove moisture from the air so that the paper quality doesn’t get affected?
Over many years, that definition changed. It became about how quickly you can cool the air and how quickly you can reduce the temperature. With climate change and global warming and the pace at which it’s happening, you are seeing the very humid conditions that people are experiencing all around the world. Now it’s going back to how air conditioners can deliver not just lower temperatures, but also reduce humidity and reduce moisture from the air and deliver comfort in the true sense and do that in a very energy-efficient manner and in a way that’s affordable for people to operate it.
Controls are a critical element — they can make the air conditioner smarter in how they assess temperature and humidity and how they optimize the compressor and the refrigerant flow and the fan speed and how all of that comes together to deliver the comfort that people need. Controls have a big role to play there.
David Roberts
One other thing that’s probably worth mentioning just in terms of the AC units themselves is I presume we could get better at reducing these leaks. That’s just more regulations, better training of technicians, better disposal techniques. Is there work underway to reduce the amount of leakage over the course of the lifespan?
Ankit Kalanki
Absolutely. Installing leak detection systems is one intervention where a lot of work is happening. Especially in the commercial sectors where you have several thousands of pounds of refrigerant inside a facility, installing these leak detection systems is a way to assess those leaks as soon as they happen. Then bringing your contractor on site to fix that. At the end of life, there is a lot of attention being given to how we ensure and incentivize contractors and technicians to recover the refrigerant at the end of life and not let it vent, and what are the right practices around it.
A lot of effort is going on and a lot of awareness is being built within the industry, within the communities to stop those leaks in the first place and at the end of life as well.
David Roberts
If you put together — this is the interesting thing to me — if you put together all the things that we already know how to do, RMI has this global cooling prize and prototypes that have won those prizes have been 60 to 75% lower electricity use than typical ACs, just using technologies that we already have.
The question is, why can’t a US consumer walk into a Home Depot and buy one of these super efficient ACs? Oddly, the answer to that question traces back to how they are tested and rated. This is the focus of a lot of your work. Talk us through briefly, what’s wrong with how we test and rate these things today.
Ankit Kalanki
That’s the crux of the problem — if they are technically feasible, then why are they not commercialized? That’s where the commercialization journey is very different from an innovation journey where you develop prototypes. Great, you have proven something. But then the commercialization journey is a long journey. There are iterations on the prototypes. You are looking at different standards for safety and for compliance, and depending on the market they can vary. Then you have to understand the market and what their needs are. That journey is where we are actively spending a lot of time, as you mentioned, through the Global Cooling Efficiency Accelerator.
Standards is one piece, Dave, which is extremely crucial in this commercialization journey. Industry designs products to standards and those standards get referenced everywhere. Whether you are looking at a building code and when they specify equipment and the performance, it all ties back to what standard is used to rate and assess the performance of those air conditioner technologies.
There is nothing wrong. I don’t blame industry there because industry is designing to standards. They have done a good job at making sure that products are compliant. They have been cost optimized to make air conditioners affordable for many millions of people around the world. Where the change needs to happen is how in the first place those ACs are rated and tested, because then industry will do it once the standards change.
David Roberts
This comes down to the difference between latent cooling and sensible cooling.
Ankit Kalanki
Yes.
David Roberts
Tell us briefly what those mean.
Ankit Kalanki
Sensible cooling means, in simple terms, temperature-based cooling. If you have to go down from 80 to 70 degrees Fahrenheit, how quickly and how efficiently your air conditioner can deliver that cooling — that’s sensible cooling. If you have a space where you are feeling very humid because relative humidity is 85% and you want to bring it down to 60%, all that effort that will go into reducing the moisture — that’s the latent cooling part, and you expect air conditioner to do both of them at the same time.
How it happens today is you use temperature as a proxy for managing humidity because air conditioners only have a temperature sensor inside them. You start with a certain temperature set point on your thermostat and when you still feel sticky or you walk into a conference room and it’s feeling cold, but it’s clammy and muggy, you will keep reducing your thermostat until you feel the relatively drier air. The air conditioner is doing that.
David Roberts
This is crucial — even cooler air, if it’s still humid, is not comfortable, and people tend to crank the temperature down further if that happens.
Ankit Kalanki
That wastes energy today. That’s the piece that standards can solve for. Standards today, based on which the air conditioners are designed and tested and rated for performance, use temperature as a way to assess the efficiency, and that’s what goes on the labels that you see on air conditioners today. It’s a purely sensible cooling-based approach to testing today. Humidity management is a byproduct because when you cool the air, there is some level of moisture that gets removed as air reaches its dew point temperature.
However, if we have to deliver better cooling, if we have to deliver cooling that provides comfort to people and does not waste energy and does that in an energy-efficient manner, we have to start thinking about how we can bring latent cooling not as a byproduct, but as a central piece of that testing protocol and the testing method against which air conditioners are designed.
That’s the kind of effort that RMI along with partners are actively working towards — how do we build on one side the awareness that this is missing today and then generate the data and the evidence through field testing that we have done and through engaging with manufacturers to then go to the standard setting bodies and say, “We need to change these standards because that’s the only way we can avoid locking in inefficiencies for multiple decades to come.” Especially when you look at the boom in air conditioning in global south countries.
David Roberts
You’ve done these field tests that show that when it’s humid, air conditioners are using up to 30% more energy than you would think from their ratings, because people are pushing them down farther than what the temperature would suggest. Currently they are wasting a ton of that energy just because that humidity piece is not getting measured.
Reading around about this, it sounds like you are making progress on this. The incoming president of ASHRAE — I’m not even going to attempt to unpack that acronym, but it’s basically the association of Heating and Cooling Engineers — sounds like he’s heard about these field tests and he’s cognizant of the problem. The ISO — everybody knows that’s the International Standards Organization — is working on a new standard and India’s Bureau of Energy Efficiency has updated some of its benchmarks. It does sound like things are moving. I wonder where that process is and what is the distance between what’s currently happening and that bright future when I can walk into a Home Depot and see a standard rating that accurately reflects these things.
Ankit Kalanki
You’re right. There has been a lot of good progress and in the right direction in regards to the standards conversation. The ASHRAE president highlighted the overcooling issue and the energy waste associated with overcooling in his presidential speech globally — he travels and addresses the technical community and the engineers. That has elevated the awareness around it. Those same people then go into the technical meetings and talk about it. That has helped us raise the awareness around it. ISO is already working on a new standard, which is a move in the right direction — it’s going to shift away from a traditional standard capacity-based approach to an approach which recognizes better controls.
With that, you can optimize the performance of your air conditioners. ISO is heading in that direction. We are hopeful that in the next couple of years ISO will come out with a fully published standard along that updated standard process and then it will come down to the countries. Once ISO publishes a certain standard, then the national standard bodies — in India, it’s the Bureau of Indian Standards; in the US it could be the DOE or the AHRI — will look at that or will already start working on it in parallel and think about how we can better acknowledge the aspects of that standard into the national standards.
Every manufacturer will design the products that are sold in the market according to the national standards and the regulations. That process takes its own time because there is a lot of consensus building that needs to happen through the technical committee efforts. This is where organizations like RMI step in, where industry players — we find the players that are really trying to take the first step and are seeing this change and acknowledge that this will happen.
It’s not about if, it’s about when and how soon it will happen. They are noticing it and they are willing to take that first step. We work with them and we work with aspirational buyers and actors on the demand side who are willing to take that step in demonstrating and deploying those technologies that can generate the market confidence that policymakers need to see ultimately to expedite their efforts on the standards front as well.
They are all interconnected. It’s not a sequential process. We have to work on all of those aspects — when one industry player jumps in, it creates FOMO and other industry players also jump in. When they see one buyer doing it, others also want to do it. Then you start creating multiple voices around it, and that’s how you start shaping the market. Ultimately that leads to the day when we walk into a store and see a product that is optimized for humidity, optimized for delivering comfort while delivering energy efficiency in the real world and not just on a label.
David Roberts
There’s also a set of problems — if a new standard drops, manufacturers, OEMs, still need the tools by which to meet those standards, and those aren’t necessarily in place. Is there work starting to build those up in advance? They need their own testing infrastructure, they need their own modeling tools that are optimized to this kind of thing. How long before some mid-tier OEM in, say, Vietnam is capable of producing these even if there is a new standard in place?
Ankit Kalanki
That’s an important question because that’s what dictates the timeline for adoption at the national level, Dave. The readiness of the local labs and the local manufacturers’ testing capabilities determines how soon and to what extent those standards will get adopted. There are efforts happening where RMI, for instance, is engaged in inter-laboratory testing, where we are looking at the different test protocols that exist that are different from what is followed today as an industry practice.
We are trying to work with those research institutions and those labs in different regions to help everyone come on the same page by showing that these new test methods are replicable, they produce consistent results. Whether you do it in Japan, India, or the US, you are expecting to see consistent results. Those are the efforts that allow test labs and industry players to build the confidence that, yes, that evidence helps build their confidence further, which then moves us to the next phase of building the consensus and moving to the adoption of the standards as well.
David Roberts
If you were pushed to guess at some sort of timeline, how long is this going to take to get these — as we say, we’re capable with this current technology of getting 60, 70% better — how long before those 60 to 70% better air conditioners are in stores in, say, emerging economies? Do you have any guess as to that timeline?
Ankit Kalanki
I will answer this question in a slightly different way. We know what and how we can reach that 60 to 70% target of super efficient ACs. How we go about that journey is we start with what is the most practical and the most feasible way to introduce products in the market that have controls capabilities that are making these air conditioners smarter in delivering comfort in the real world. You can do that with existing set of compressors, with existing set of heat exchangers, what exists today. Supply chain readiness is also important when you think about emerging economies and where they are and the policy ecosystem there.
Knowing what exists today and what manufacturers are able to do today, taking that first step of advancing controls by making your air conditioner better respond to both temperature and humidity can instantly deliver 15 to 20% savings right off the bat. I feel confident that could happen in a matter of a couple of years, because you are not looking at establishing a new supply chain or finding a new vendor. You can work with their existing vendors and you can do that.
From there on, the journey goes on to advancing towards that 60 to 70% number where controls is part of that. But now you have to think about compressor technology and you have to think about heat exchanger technology and what exists today and where is the innovation happening —
David Roberts
And the regulatory updates, the standards updates.
Ankit Kalanki
Regulatory updates, yes. Manufacturers are in a tricky business. The air conditioning industry is not a very profit-making industry. The margins are very tight and they rely on commodities — copper, aluminum, plastic. That’s the core of what makes an air conditioner today. When you are thinking about, on one hand, industry is being asked to constantly raise the efficiency benchmarks and the efficiency of their products while keeping the products affordable, while keeping the supply chain domestic, all of that.
It’s a complicated and complex problem and a multivariable problem to solve for. This is why a phased approach is something that we can really make good progress with. These updated products that have existing hardware and use better controls can immediately bring savings to people, to the power grids, to the environment. From there on, we can continue to go towards that ceiling and ultimately achieve that 60, 70% target.
David Roberts
Let’s pull the lens back a little bit from the AC units themselves. Let’s talk about the buildings that these AC units are in. There’s lots you can do with buildings to reduce how much cooling you need in it. Maybe can you just mention a few of those things?
Ankit Kalanki
I like to think about it as you don’t need air conditioning in the first place. Start with thinking about your building and how you can reduce the cooling need inside the building by measures like shades, ventilation, and insulation. Windows, better insulating windows. Paint your roofs with materials that can reflect and radiate the heat into outer space. All of that can have a significant impact on the amount of heat that gets trapped inside the buildings that ultimately gets radiated through the walls and through people.
Once you do that, your heat load that has to be removed to outdoor that we talked about in the very beginning is significantly reduced. You can now reduce your size of the air conditioner or in some cases maybe you don’t even need an air conditioner depending on where in the world you are. It’s very important.
David Roberts
Then of course you’re getting into building codes, construction codes, all that stuff. That’s a whole rabbit hole we could go down. But one thing I did want to take a brief look at just because I’m fascinated by it — I should probably do a separate pod on this — talk briefly about these passive daytime radiative cooling materials. Everybody is familiar with painting roofs white. That reflects a lot of heat away. That alone can do a lot. But then they have these special new paints, these special new materials. Say a word briefly about these things because they seem like magic to me.
Ankit Kalanki
It is fascinating. PDRC, or Passive Daytime Radiative Cooling Products, can take many forms. Paint is one form they can take. The interesting thing about them is that they reflect the heat like a typical white paint would, much more efficiently, but they also radiate the heat. The infrared portion of the sunlight, which is the heat component, and also from the indoors, these PDRC materials can transfer all of that heat to outer space in a very narrow window.
David Roberts
It goes right through the atmosphere.
Ankit Kalanki
Yes. There’s a very narrow window when you think about the science behind it — a very narrow window in the atmosphere of 8 nm to 15 nm between which you have to produce that radiation or that reflection for it to pass to outer space. These PDRC materials have been tuned in a way and have been innovated in a way where they enable that heat to go into outer space through that narrow window. That’s the beauty of it, where you can achieve significant reduction not just on the surface of the roof, but also indoors, because it’s able to radiate the heat also from the roof.
David Roberts
You can actually — it can help your building be below ambient temperature.
Ankit Kalanki
Yes.
David Roberts
Actively cool the building. It’s wild to me. When you think about it, it’s not just reflecting the sunlight away, it’s sending heat out into the atmosphere. In some tiny way, it’s helping with global warming too, in a very marginal way, but absolutely fascinating. Just on white roofs, I constantly have people ask me whenever this comes up, and I’ve had the question myself, which is — that just seems so obvious and easy.
They’ve done studies where if you paint a bunch of roofs white in an urban area, you can reduce this urban heat island effect. Where heat concentrates in urban areas, you can keep buildings cooler. White paint is not expensive. Why isn’t there more of that? Why isn’t that the default? Why haven’t we seen that spread faster and become more ubiquitous? Do you have any theories on that?
Ankit Kalanki
There are some practical aspects of why the scaling has not happened at the pace at which we would like it to be. Similar to air conditioner technology — technology is not the problem, it’s the other elements of it, when you think about commercialization and deployment, that have to be considered as well.
A couple of things that are important to note which impact the adoption at scale: one is the reflection itself and the glare that comes from just painting everything white. That has been raised as a potential concern. There are efforts to solve that. That’s one of the concerns — if you paint everything white, the glare becomes a concern and an issue for people in the surrounding areas or in surrounding buildings.
The second is depending on where you are in dense urban environments, where you have tall buildings, skyscrapers, all that reflected heat might just bounce between the different buildings and it might just remain trapped. It is reflecting from one roof, but then it might get reflected back through other surfaces. It’s not a solution that can be just applied anywhere, but context specific, yes, it can definitely be applied and needs to be applied.
The third more practical thing is the wear and tear — when it rains, if you live in an area where there is a lot of debris or dust, the effectiveness of that traditional white paint also gets impacted. There are more efforts needed to solve some of those practical aspects of the work. While they are great in reflecting the sunlight and in studies we have seen the numbers in terms of how much delta on the temperature standpoint they can get, from a durability standpoint, there is more work needed for them to get really adopted at scale.
David Roberts
The PDRCs, these magic materials that reflect the infrared out into space — are they commercial at any scale yet?
Ankit Kalanki
There is a lot of active testing happening of PDRC materials in different forms, as a film on solar panels, as a paint. There are a lot of startups, including organizations like RMI, that are supporting these startups to test the veracity of the claims of some of these PDRC products to generate more evidence and generate more awareness. That is where we are at this point. We need to do a lot of evidence generation around not just these technical and performance aspects, but also on some of these durability aspects so that they can really build that confidence among the policymakers and among the adopters in different parts of the world.
David Roberts
Interesting. Now briefly, let’s pull the lens back even farther from the building to the city, to urban design. There are also things that city planners can do to provide comfort, because that is ultimately what we’re about — comfort. Talk about a few of the things you can do at the neighborhood and city level to help cool people.
Ankit Kalanki
This work that happens at the city level and urban level is a key part of building resilience. Whatever we talked about until now, everything is inside the buildings or impacts people inside the buildings. But then you have people that are working outdoors. Urban level measures and urban heat mitigation measures are crucial if we are to truly address the need for cooling and tackle this heat issue for people around the world. Some of the ways in which urban heat mitigation happens — greening the spaces, planting more trees. There are efforts happening around that. A lot of policies at the local level, at the municipal level, are encouraging green spaces for people.
Establishing cooling centers is another way where outdoor workers can go to these spaces that have some form of a cooling mechanism, whether it is fans or evaporative or mist-based cooling or air conditioning, where they can get some respite.
The most fundamental part of this is when you think about urban heat — how can we inform people in a timely manner so that they can take the appropriate action? Multiple cities do this in many different ways. You have warning systems and announcements that happen. More and more of that is now becoming a priority for local administrations where they are increasingly using technology and using weather data to inform people about these heat issues in advance so that they can either plan their work properly or they can take breaks accordingly so that they don’t cross a threshold which might impact productivity and, in some cases, maybe even become fatal, given the extent of the heat.
David Roberts
A couple other specific questions about this. One of the things that occurred to me is every city everywhere has tons of pavement, roads, and parking lots. Pavement is of course black or very dark, so it absorbs heat. Anybody who’s been to Phoenix, Arizona or anywhere knows that the pavement itself can become hot enough to genuinely be painful. Is there any way to make lighter colored pavement? Is that a thing?
Ankit Kalanki
It is a thing. RMI has tested that in India, in Palawa City, near Mumbai. We have seen between 3 and 5 degrees Celsius of temperature change with light-colored tiles and reflective blocks. It is a thing and it exists. We have tested them in India as well.
David Roberts
One other piece which is fascinating to me is district cooling. Of course, Volts listeners are familiar or should be with district heating where you make heat centrally and then pipe it to buildings. But there’s also district cooling where you’re doing this same cycle, but on a larger, more industrial scale and then piping the air. Is that common? Is it spreading? Is that a big piece of the puzzle here?
Ankit Kalanki
It is an important piece of the overall solution set. There is no one-size-fits-all solution when it comes to how you provide better cooling to people. It is so context dependent. District cooling is one piece of that broad, big puzzle on how you provide access to cooling to people. Especially if you think about mixed-mode developments where you have a good mix of residential, commercial, industrial, office spaces where the cooling load is fairly consistent on average — those kinds of setups, those kinds of parks which are coming up in many developing countries. District cooling is a good solution for those kinds of setups. In traditional dense urban environments, it is hard to have all that centralized system and piping and delivering cooling.
David Roberts
Especially if you’re trying to retrofit already built environments.
Ankit Kalanki
Correct. But in these new projects that are coming up, if you can plan them properly, and if you can have a cooling load that is averaged in a way where you can meet everyone’s demand, district cooling can offer a good opportunity to reduce the cost for consumers because then you can think about it as the project developer will be incentivized to invest in the most efficient solution instead of a low-efficiency product. They will be getting paid by how much cooling they deliver. The more efficient they are with their systems, the maintenance of their systems, the more incentive they have and the more profitable it is.
It could be a win-win for people where consumers don’t have to own the asset, they don’t have to worry about the upfront cost, they just have to pay for the cooling they use. The developer and the operator are incentivized to invest in the most efficient system and better maintenance because that way they can improve their financing position as well. In that way, district cooling has potential, but it’s context dependent.
David Roberts
We don’t have a ton of time left, but there’s a whole — here we come to a thing we could do a whole pod on — most of what we have talked about, and I think most current effort and most of your hopes for the near and midterm future are around improving the basic vapor compression systems as they exist today, making them work better.
But there are under development here and there among startups and labs some fundamental alternatives emerging. We could just run through a few of those quickly. We could start with desiccants because those are the closest and are even being integrated into vapor compression. Talk a little bit about that first.
Ankit Kalanki
It comes back to humidity where we started. Desiccants are a solution to manage that humidity in an effective way. We are seeing a lot of innovation from startups. Multiple of them are also supported by RMI through our Third Derivative program. They have developed desiccant materials and innovation in that desiccant material space where they integrate or attach onto an existing vapor compression system and they can independently and separately manage the sensible cooling or the temperature and latent cooling or the humidity. That way your air conditioner doesn’t have to overcool the air to remove the moisture.
Now the desiccant takes care of that humidity and the moisture removal, it sucks the moisture out of the air, makes the air dry. Your vapor compression system is only doing enough to reach the temperature that you feel comfortable at. That’s one area of innovation which has a lot of potential and a lot of startup activity.
David Roberts
Desiccants are materials that absorb moisture, more or less?
Ankit Kalanki
Correct. But they can be in liquid form and solid form. There are varieties of it. Fundamentally they are the ones that suck the moisture out of the air.
David Roberts
You suck the moisture out and then the dry air goes into the traditional vapor-compression system. But it has to do less work.
Ankit Kalanki
Correct. The innovation piece in the desiccant solution set is how do you regenerate that desiccant. That’s the piece which often gets missed. While you are solving one problem, you don’t want to create another problem where you are now spending energy to regenerate that desiccant because that desiccant material, like any other moisture absorbing or water absorbing material, will get saturated as it absorbs more and more moisture. How effectively and efficiently can you regenerate that desiccant so that it’s ready to work efficiently?
David Roberts
When you say regenerate, are you squeezing the moisture back out of it or are you replacing it with new desiccant?
Ankit Kalanki
Squeezing the moisture back out of it. You need typically a heat source to do that process. How efficiently and innovatively you do that is what will determine the overall efficiency of the system when those desiccants are integrated into the solution set.
David Roberts
Those are actually — Amazon, I read, is deploying systems that involve those desiccants commercially now. Those are pretty close.
Ankit Kalanki
That was exciting news from two weeks ago. Amazon partnering with a startup, Transera, to deploy their product was exciting to see.
David Roberts
Then there’s solid-state thermoelectric cooling. What the heck is that?
Ankit Kalanki
You mentioned one way of solid state cooling. There are more terms like that. There is barocaloric and there is magnetocaloric, thermoelectric. What solid state cooling is — you use solid materials to produce the heating or the cooling effect by applying some force. That force can be a pressure, a magnetic field, or an electric field. When you do that with that solid material, it undergoes a phase change. The crystals in the solid, their alignment changes. As a result of that, there is a phase change that happens and you can generate heating and cooling.
This is an exciting area of innovation where a lot of startups are working on all these kinds of caloric solutions — barocaloric, magnetocaloric, thermoelectric solutions. A lot of good activity and a lot of potential. Also because of two reasons. You don’t need a compressor, because you don’t have a refrigerant gas. That’s what makes it exciting and compelling in the context of the current refrigerant transition that we are in.
David Roberts
Because we still don’t have that perfect refrigerant. You eliminate refrigerants, you eliminate the compressor — which is the vast bulk of the electricity demand.
Ankit Kalanki
Yeah.
David Roberts
Are those installed anywhere or is this all lab and prototype stuff?
Ankit Kalanki
I don’t know about the commercial installation, but I know that one company which is supported by RMI’s Third Derivative called Magnotherm, from Germany, has developed a beverage cooler or a wine cooler using magnetocaloric technology.
David Roberts
Where you’re applying a magnetic field to this solid material?
Ankit Kalanki
Yes.
David Roberts
It’s wild. I’m assuming that similarly to solid-state batteries, it’s a lot less maintenance because you have a chunk of solid material. You don’t have as many moving parts.
Ankit Kalanki
It’s early to comment on that because of the nascent nature of these technologies, because you still need pumps and mechanisms to move the fluid. The material can produce the heat and the cool, but then you have to move that heat and cool to wherever you need it. You still need some of those pieces and the parts of heat exchange — heat exchanger and valves and the pumps and the fan — to ultimately deliver that cooling. There is much more to be learned and discovered about these from an overall maintenance standpoint as these units start to get into the field in the coming future.
David Roberts
I’m curious about your long-term view about the relative effort and hope we should be putting into improving vapor compression units like we have been talking about for most of our time, versus improving and scaling up some of these very promising alternatives. Which do you place more hope in in the mid term and long term?
Ankit Kalanki
I will answer that question slightly differently because I think we should be really looking at better cooling and whatever it takes to deliver that better cooling. If urban heat mitigation measures are required to address the needs of certain aspects of society and community, those solutions need to happen at the right scale. All efforts need to happen to build that resilience and mitigate that urban heat.
Wherever there is new construction happening, let’s make sure that our buildings are designed in a way that reduce that heat trap inside the building so that we can reduce the need for that mechanical cooling in the first place and deliver better cooling to people inside the spaces.
We have to do everything we can to avoid locking inefficiencies in our systems and making our grids stress during the hottest days by significantly improving the efficiency of the products. It’s not about stopping people from buying air conditioners. When people cross a certain threshold, they will buy an air conditioner. We have to think about how to make it more efficient.
In that context, in the short to medium term, there is a huge opportunity and a lot of effort should be put towards improving the existing vapor compression technology because the entire ecosystem is designed around it — from an industry awareness standpoint, from a consumer awareness standpoint, from a policy and standards standpoint. We should put all our heads and minds to solve that problem of how do we get vapor compression technology to its ceiling and not just focus on raising the floor, but how can we really start pushing the overall efficiency of the air conditioners towards that ceiling that we have demonstrated through projects like Global Cooling Prize.
In parallel, we have to start thinking about what application requires what kind of cooling. Do we need vapor compression-based technology everywhere or for a product like a wine cooler or a vending machine which is just sitting in a shopping mall in a corner, can we use a more novel and sophisticated technology? We need venture capital partners, we need innovators, we need adopters to come together to support these upcoming technologies so that we can start creating a market for these solutions as well. We do need a buckshot of solutions — not just one silver bullet of solutions.
David Roberts
You don’t worry at all that the traditional vapor compression dominating the standards development and all that stuff — you’re not worried about that process boxing out new disruptive entrants? You think these can peacefully live together and proceed alongside one another?
Ankit Kalanki
It’s an interesting question. There is an opportunity to build partnerships here because while the industry is doing its part of pushing the ceiling through, we are helping them to continue to do that. They’re doing that. They’re also looking out for other opportunities.
Let’s be honest, industry has the scale, industry has the capability to test products. Industry has the capability and the network and the voice to get the products certified. Startups should think about how they can collaborate and partner with these manufacturers and create value for the community and for the ecosystem. They will need each other to ultimately solve the cooling problem and scale these exciting, innovative products that are needed to solve the access to cooling issue.
David Roberts
Final question — I’ll ask you to speculate a little bit, look down the road a little bit. If you listen to these IEA projections, you just look at the current trajectory, it’s pretty dire. It’s pretty dire. Maybe I should have emphasized this more at the beginning, but this is not about luxury. This is about survival for a lot of people. The earth is getting hotter. No one involved in any of this wants to deny the best cooling technology to people who are going to be living in these hot and humid environments that are coming.
This is not something we cannot do. But if you look at the projections of the impacts of doing it, it’s pretty dire. It’s going to be an enormous chunk of global greenhouse gases. What is your — are you bullish on progress here? Do you think those projections are going to be overstated? Do you think we’re going to manage to pull this off and to hit that ceiling and to reduce the need and what do you worry about in terms of blockers or problems — what’s the knottiest part of this problem to you and how optimistic are you about getting through it?
Ankit Kalanki
I do think that we have all the solutions that we need to bend the curve. We have a good understanding of what it takes to mitigate urban heat. We have solutions for that. We have solutions that can reduce the heat trapped inside the buildings or prevent heat gains inside the buildings through passive measures. We have solutions for that and we know what it will take for others to adopt it also. We know from a technology standpoint what solutions can bend the curve from an energy and emissions and peak demand standpoint.
I agree with you that it should not be treated as a luxury anymore. Cooling access is critical for health and safety. The goal is not about less cooling. We have to deliver better cooling. Where people need more access to cooling, we have to make and find ways to deliver better access to cooling where we can avoid the waste, where we have to avoid that waste in all forms, whether it is refrigerants, whether it is electricity consumption. We have to ensure that air conditioners and any aspect of the cooling technology and cooling solutions can really support the power systems that often get stressed during the hottest parts.
To the second part of your question — the knottiest part?
David Roberts
What keeps you awake at night?
Ankit Kalanki
What keeps me awake at night is when I see the projections of cooling electricity consumption tripling from 5,000 terawatt hours, which is the same as what the US consumes today, entirely, to 18,000 terawatt hours by 2050, which is the entire electricity consumption of the US, China, India, Japan, and Germany — five major economies of the world. That keeps me awake. At the same time, the potential that we have demonstrated — that RMI, through its Global Cooling Prize Initiative and the Global Cooling Efficiency Accelerator Initiative, has demonstrated what’s possible — that keeps me hopeful, motivated, and also awake that we can solve this problem.
David Roberts
Awesome. That sounds like a great place to wrap up. Ankit, thank you so much. This has been extraordinarily illuminating. I appreciate it.
Ankit Kalanki
Thanks, Dave. It was great to chat with you.
David Roberts
Thank you for listening to Volts. It takes a village to make this podcast work. Shout out especially to my super producer, Kyle McDonald, who makes me and my guests sound smart every week. It is all supported entirely by listeners like you. If you value conversations like this, please consider joining our community of paid subscribers at volts.wtf, leaving a nice review, telling a friend about Volts, or all three.
Thanks so much and I’ll see you next time.
