Rethinking air conditioning amid climate change

What kind of alternative refrigerants are we talking about? Can you give me some examples?

Some of them can just be things like carbon dioxide, actually, which can be used as an alternative refrigerant by using the thermodynamic properties of gases and methods common to heat pump technologies. CO2-based cooling systems use highly compressed CO2 and then manipulate the pressure of the gas. When the gas expands due to reduced pressure, it absorbs heat. Unlike many common refrigerants that can have greenhouse gas potentials orders of magnitude greater than CO2, any CO2 that leaks from these cooling systems has minimal warming potential.

Are we planning on industrializing the process of using alternative refrigerants? Are there any processes already on the market? Or is it only in the development phase?

I think there’s definitely major interest in some of these new alternative coolants. And they can be very effective. I think there is a challenge, though, in that a lot of our installed equipment has these historic HFCs in them. And so even if we have alternative refrigerants that go in newly installed equipment, we still have this overall stock of refrigerants in our buildings, air conditioners, and refrigerators that causes a major warming threat, particularly when the devices are at the end of their life.

Why are you so interested in the growth of this industry for developing nations? How much is the refrigeration industry expected to expand in these parts of the world?

One of the big reasons to be concerned about cooling services, as an industry, is the tremendous expected growth, not just in one but in two major sectors. The first is in building cooling, which includes air conditioning of spaces. The second is product refrigeration—keeping products like meat, vegetables, and vaccines cool and safe throughout their supply chains.

Both of these services are currently experiencing, or are expected to experience, rapid growth in developing countries in the coming decades. If we don’t deal with cooling services as an industry and reduce the overall environmental impacts, then we will see tremendous growth in environmental impact.

When you look at things like household air conditioning, in much of the developing, world they don’t have broad access. But we’re facing an increasingly warming climate, so the demand for cooling services, particularly in buildings, is going to be critical for health and safety.

People are getting wealthier and paying for cooling services. The most efficient kinds of air conditioning are centralized systems that will heat entire buildings and residences. Unfortunately, that is often offered at a price point that is outside of the consumer’s ability to pay and which requires massive retrofits of existing buildings. That’s why we will be seeing a lot of room air-conditioning units being installed in major cities of developing countries.

Apart from the warming impacts, are there other kinds of environmental impacts that we should be worried about?

The big ones do tend to be associated with global warming potential. But anything that requires energy has all of the impacts associated with the electricity sector. If you’re talking about electricity grids that rely largely on coal, you have a lot of localized air quality emissions; you have mining emissions associated with coal mining; and the whole slate of toxins and other air quality issues associated with the burning of coal.

How serious do you think this problem is? To what extent does the refrigeration and air conditioning sector tend to damage the environment?

It goes back to this idea: Cooling spaces requires a tremendous amount of energy. Even very efficient air conditioners and refrigerators require a lot of energy to operate. If we don’t have a clean energy grid, there are always going to be environmental impacts associated with the expansion of cooling services.

That said, even if you had a perfectly clean electricity grid, you still have the refrigerant emissions associated with cooling. So you don’t ever erase the global warming potential, at least with our current existing stock, but you certainly can reduce it by reducing grid emissions.

What kind of interventions can we apply to this existing system?

I always think of them in two bins. One directly impacts the technology, and one indirectly impacts the technology.

For direct interventions, we can come up with alternative refrigerants to replace high global warming-potential refrigerants. We can also find ways to reduce the overall energy needs of providing cooling services. That can come in the form of making more energy-efficient equipment or changing consumer behaviors, like having a slightly warmer environment in office spaces and residential spaces.

For indirect interventions, we need to think more broadly about the built environment to reduce the need for air conditioning technology. This often takes the form of better building design and reducing urban heat island effects. It can also go with varying air conditioning and refrigeration loads according to time of day and actual need. There are a lot of ways that we can think about making air conditioning and refrigeration smarter, not just in terms of the technologies themselves but also in terms of managing energy use.

Are there systems or industries or companies that are already using these kinds of innovative techniques? Can you give me examples?

In terms of direct interventions, there are a lot of activities that are incredibly promising. So again, we have the Kigali Amendment to the Montreal Protocol, which is trying to phase out high global warming-potential refrigerants in favor of low global warming-potential refrigerants. It’s going to take a while, but we’re going to get those new refrigerants into the marketplace.

The second major thing is energy-efficient appliances. Depending on the specific country, there are manufacturing labels and certifications for room air conditioners or household refrigerators that have energy-efficiency ratings. In the US, it’s Energy Star. In Europe and Asia, they have a variety of certifications and labels to highlight to consumers that these are less energy-consuming devices.

And then the other thing is smart intervention, like using smart thermostats in homes and offices that adjust air conditioning according to the time of day and when people occupy spaces.

Do you see an emphasis from governments or any other sector on this industry? Are these issues being addressed in major climate conferences like the Conference of Parties?

Cooling services as an industry get missed quite a lot. Cooling services span across different sectors, so we have a little blind spot to it. And it often gets lost in the overall conversation. I haven’t seen much focus on this industry at such meetings.

Our group is really trying to highlight the importance of cooling services as an industry.

Hmm... I agree, because I realize that when talking about global warming, impacts of transport or manufacturing factories come up pretty much all the time, but I think we find it hard to view the cooling industry as a separate entity. You’ve also mentioned that reducing food waste can reduce demand for refrigeration services. Can you briefly elaborate on that?

Often, when we try to think about reducing the environmental impacts of technology, we tend to focus on the technology itself, but that’s not always the most impactful intervention. Often, we have to step back and think through why we’re using the service in the first place. And that gets to thinking through the sectors that cooling services support.

Food, as a sector, is incredibly environmentally impactful. The cold chain—which is refrigeration throughout a food supply chain—is important in keeping food fresh and safe. But globally, we waste about 40 percent of our food that is produced. In developing countries, much of the food waste happens throughout the supply chain before it reaches the consumer, largely due to lack of cooling services.

Whenever you reduce food waste, you save energy since there is no longer a need to cool food that will never get eaten. And so, while it’s not an intervention that a lot of people normally would think about, by reducing food waste, we reduce the need for more cooling services. And as you reduce food waste, you reduce all of the environmental impacts of agriculture as well as the services associated with the whole food supply chain.

Are there promising startups or companies already working on making eco-friendly refrigeration or a smart refrigeration system?

Certainly, some of the major refrigeration companies are thinking about new models. There are things like district-level cooling, in which rather than having lots of room-based air conditioners, this new system tries to have an efficient centralized system that doesn’t just cool a single residence but lots of houses.

Some of the big things in this area where we are seeing activity among startups are food coatings that improve shelf life and reduce the need for refrigeration of some foods and improved artificial intelligence in sensing systems for both air conditioning and refrigeration. Rather than setting air-conditioner activation at a certain time and temperature, sensors can automatically adjust the temperature according to the number of individuals in a space. That way, you’re not cooling spaces that don’t have people in them. We can employ better sensing technologies on products for food safety and security issues and make sure that various products maintain specific temperatures.

Nice. And how can scientists and researchers contribute more to solving problems associated with this industry?

There’s a lot that needs to be done from an industry and policy perspective, but individual households and individual people may feel like they can’t really do anything substantial. So I think trying to find things that households can do to have an impact and feel like they’re contributing to solving a problem is really important. Promoting things like energy-efficient devices, thinking through things like reducing household food waste as something that can reduce your greenhouse gas footprint, can be really, hopefully, impactful.

Is your team exploring more on this topic?

The environmental impact of cooling services, I think, is a really important topic and one that our group continues to explore. We are really interested in the intersection of cooling services and avoidable food waste. As the cold chain expands, particularly into places like Africa that don’t have a very well-developed cold chain, what are the environmental impacts of increasing the cold chain presence?

On the one hand, you have the ability to extend the shelf life of foods and increase food security. But on the other hand, you’re increasing overall energy use in the food system. Are there ways that we can bring the benefits of the cold chain to developing countries without the environmental impact? That’s the major question that my research group is trying to tackle.

This story originally appeared in Knowable Magazine.