In Conversation with Associate Professor Riccardo Paolini

Published on the 30 April 2026

Associate Professor Riccardo Paolini did not start out thinking about cities. Trained as an engineer, his early work focused on building energy efficiency and reducing heating demand.

But that began to shift. As cities grew and the climate warmed, cooling became harder to ignore.

“It’s different,” he says. “With cooling, you quickly realise there is only so much you can do at the building scale.”

It meant looking beyond the building, to the wider urban environment and how it shapes heat day to day.

His work now spans research, teaching and professional education, including the Managing Urban Heat short course, where he works with practitioners to better understand how cities respond to rising temperatures.

We spoke with Riccardo about urban overheating, how it is changing everyday life and why addressing it requires more than a single solution.

How did you first become interested in the relationship between buildings, cities and heat?

My story is quite common in this field. By training, I am an engineer working on building energy efficiency. Initially, the focus was on reducing heating demand, but over time it shifted to cooling as cities grew, the climate warmed and air conditioning became more widespread.

Cooling is different. With heating, we have well established solutions. But with cooling, you really need to step outside and look at the urban environment. There is only so much you can do at the building scale, so it forces you to change how you think about it.

People tend to focus on urban heat in summer, but heat islands exist in winter as well. In colder climates, they can be beneficial because they reduce heating demand, so in that case you want to exploit them rather than mitigate them. That is what interests me.

How would you explain urban heat to someone encountering the concept for the first time?

In Australia, there is quite a lot of different terminology being used. In my field, we often prefer to use the term urban overheating, meaning the excess heat that we do not want, especially in summer, as opposed to the heat we may benefit from in winter.

At its simplest, it is the fact that cities can become hotter than they need to be, and often are hotter than they need to be, and this is the result of a few main things. Cities are denser, with buildings closer together, which reduces cooling from the wind. Materials like pavements absorb and release heat, there is less greenery and shade, and we also add heat through things like air conditioning.

There are also regional effects. In Sydney, for example, there is a clear difference between coastal and inland areas due to sea breezes and air movement. And then there is global warming, which raises overall temperatures.

All of this means urban areas are consistently hotter than their surroundings, sometimes by a few degrees or more.

Is urban heat always something we need to reduce?

Not necessarily. Heat isn’t always a problem. In winter, especially in colder European cities, the urban heat island effect can be beneficial because it reduces heating demand. It is in summer that it becomes a challenge. So, it really depends on the season and the context.

In what ways does it change everyday life in cities?

People often think about solutions like air conditioning, but that does not account for energy poverty. Not everyone can afford to stay cool. Even if we imagine a future with abundant renewable energy that's free, urban heat will still have other impacts.

One of the biggest shifts is behavioural. People tend to live more indoors, and that is happening more and more. When it is too hot, people retreat inside.

We saw this in a project in Parramatta called Too Hot to Play. After a certain temperature, people stop using playgrounds, or they arrive, realise it is too hot and leave. They go to shopping centres or stay at home. Outdoor public spaces become quieter and less active. The “activity” instead shifts into private or commercial environments, which not everyone can access in the same way. There is a risk that we lose the Australia as we know it, with more indoor living and interactions that are time and pay constrained.

What are the longer-term impacts of that?

There is less social interaction. Cities start to become closer to places like Dubai, with more indoor living and interactions happening in private or commercial spaces rather than in public.

There are also significant health effects. Higher nighttime temperatures affect sleep, especially during prolonged heat, and that has a direct impact on mental wellbeing. Without that relief at night, it becomes much harder to recover from the heat of the day.

Heat also reduces physical activity. It changes how people move through the city, whether they walk, cycle or use public transport. It affects productivity as well. Over time, it really does shape how people experience life and interact with the cities they live in.

We’ve seen record-breaking heat events globally in recent years. 

How is this changing the way cities need to respond?

In many cases, we are still getting the basics wrong. Trees are often treated as an afterthought in development. They are planted too late, with too little space to grow and never reach maturity. At the same time, we are losing established canopy, which is far more valuable.

There are some positive shifts. For example, we are moving away from dark roofing towards more reflective materials, which helps reduce heat. But change is slow and much of the existing building stock is not designed for these conditions. Even with the best available solutions, we can only reduce urban temperatures by a few degrees at scale. That makes a difference, but it is not enough on its own.

So, the focus needs to shift. Rather than trying to fix everything everywhere, we need to prioritise key places. Transport hubs, playgrounds and public spaces where people spend time. These are the areas where shade, greenery and targeted cooling can have the greatest impact. That is how we keep cities liveable and functional as temperatures continue to rise.

From cool materials to greener cities, there are many proposed solutions. 

What is working in practice?

There is no single solution. You need all of them, and they are not in competition.

Often the conversation gets simplified to just planting more trees. But trees alone are not enough. In very high temperatures, they become less effective. They can lose leaves or reduce evapotranspiration to protect themselves. That is why you also need cool materials to keep temperatures down, so trees can remain functional. And you need water systems to support greenery because without that they cannot survive or perform well.

The key message is that these strategies must work in synergy. There is no silver bullet, even if that is what people often want to hear.

Where can architects, planners, engineers and policy makers have the greatest impact right now?

A big part of it is design, especially how we use space. There is no point having an energy efficient building if it is oversized and mostly empty. You are still cooling a large volume and that wastes energy.

Architects have a key role here. Designing space efficiently reduces energy demand and frees up room for greenery. If we avoid oversized homes, we create more space for gardens, which then contribute to cooling.

This connects back to the bigger picture. It is not one solution. Efficient design, greenery and materials all need to work together. But getting the fundamentals of space right is a big thing that can go a long way.

You are involved in UNSW’s Managing Urban Heat short course.

Why is this kind of learning important right now, and what can participants expect to take away?

It is important because we are already behind, but we have not failed yet. There is still time to act, but we need to be more rigorous in how we do it.

One of the key gaps is performance. We do not measure enough and we do not talk enough about what does not work. There is a strong focus on best practice and success stories, but for me as an engineer, I learn from failure. That is a big part of what the course focuses on. We look at how to monitor and evaluate urban heat mitigation in real conditions, and how to understand whether something is actually working.

Participants come away with a more critical, data driven perspective. Not just what the solutions are, but how to assess them in practice, what to look for and how to improve outcomes.

Outside of research, what is one everyday place or moment where you notice urban heat the most?

The bedroom. Nighttime temperatures have been getting higher over the past few years. We are now seeing 26, 27, even 28 degrees late in the evening and through the night much more often than before. During the day, the difference is not always as strong. It is overnight, when temperatures stay high, that you really feel it.

Is there a message you think is urgent for cities right now?

We are starting to see a shift where some people are asking, why are we doing this? There is a growing idea that we can simply adapt by staying indoors with air conditioning. Technically, that is possible, even in extreme heat. But is that the kind of city we want?

We are also seeing a shift where some are starting to accept living more indoors. But the issue is not just being indoors, it is how we interact with others. Cities rely on shared, public life. If enough people stop caring about outdoor environments, we risk losing that. And once that shift happens, it flows into how we make decisions as a society. You do not vote for trees, for cooling or for better streets and playgrounds if they are no longer a priority.

The real risk is that we lose the window of opportunity to act. Not from a technical perspective, but in policy and decision making.

Learn more about Associate Professor Riccardo Paolini’s research, projects and achievements by visiting his UNSW Staff Profile.

Learn more about the Managing Urban Heat short course. 

Learn more about the High Performance Architecture Research Cluster.

Learn more about the UNSW School of Built Environment.