TECH

How chameleon materials adjust to climate extremes in real time

Every summer, our cities burn energy to keep us cool. The same happens in winter with the increasing demand for heating.

But what if we don't just treat our comfort as an issue that can only be solved through hammering the air conditioning or heating? What if our buildings, clothes and infrastructure could have chameleon-like properties and adapt with the seasons?

This is exactly the kind of thinking we are doing at the University of Melbourne when we develop and engineer new materials as we navigate towards net zero.

The great energy challenge isn't just about clean energy generation but also energy preservation.

The energy challenge isn't so simple...Heating and cooling consume nearly half of all energy used in buildings worldwide. And as our weather becomes more extreme, it demands more climate control, heating and cooling. This increases the reliance on energy sources, driving up both emissions and the cost of climate control.

We could keep using more and more air conditioning, adding heaters and very thick insulation, but that's not a solution.

We already spend over half of our energy consumption dollars on climate control—and conventional insulation doesn't adjust with changing conditions. It stays static, unchanging.

A key part of solving this complex problem is smart materials.

We already spend over half of our energy consumption dollars on climate control. Credit: tu nguyen from Pexels

Chameleon-inspired materials...At their core, chameleon materials are phase-change materials engineered to sense their environment and respond in real time, without needing to consume extra power.

One of the stars of this innovation is vanadium oxide, particularly vanadium dioxide (VO₂), which transforms when the temperature changes by just a few degrees. Depending on the temperature, vanadium dioxide's atomic structure changes.

In its cool state (insulating), it transmits infrared radiation, allowing heat through. In its hot state (metallic), it reflects infrared radiation, blocking heat.

So, in summer, VO₂ becomes metallic and reflects solar heat, keeping interiors cool without air conditioning. In winter, it remains insulating and transmits solar warmth into the building.

This remarkable process happens in fractions of a second and repeats millions of times without degrading. No batteries. No electronics. No external controls. Just physics.

How it all works...To understand how these materials "sense," we need to look at them at the atomic level.

Vanadium dioxide exists in many crystal structures and shapes. Let's focus on two: monoclinic (at low temperatures) and tetragonal (at high temperatures).

Each structure has a fundamentally different shape—optical (what it lets through and what it reflects) and electronic (how good of a conductor it is).

Below the transition temperature, vanadium dioxide is an insulator.

Electrons are locked in place, unable to move freely. The material's crystal structure keeps them trapped. This insulating state also means the material strongly transmits infrared radiation—that's the wavelength we experience as heat.

Cross the transition temperature and something dramatic happens. The crystal structure rearranges.

Vanadium atoms shift position by just a fraction of an angstrom, infinitesimal distances, but still enough to unlock electron movement. The material becomes metallic and conductive.

Simultaneously, its optical properties flip: now it reflects what we experience as heat (infrared radiation). This is a chameleon-like transformation that happens almost instantaneously once the threshold is crossed.

The material literally "senses" temperature through its atomic structure, triggering adaptation without any external device or additional power.

Engineering for scale and durability...When phase-change coatings are applied to windows, roofs or building facades, the energy impact is substantial. On hot days, the material becomes metallic and reflects infrared heat, reducing cooling loads.

As evening temperatures drop, it returns to its insulating state, which transmits infrared radiation, allowing the building to cool naturally by radiating heat to its surroundings. But moving from laboratory to the real-world requires solving some practical challenges.

We are developing scalable manufacturing methods. Durability is also critical: materials must withstand UV exposure, pollution, thermal cycling and weathering without losing responsiveness.

We need to engineer materials that are not only smart but sustainable from production to end-of-life.

A tool for climate action...Chameleon materials are a fundamental shift in how we approach energy and climate. Instead of engineering larger, more powerful systems to adjust to extreme changes, we're engineering materials that respond in real time, continuously optimizing their interaction with their surroundings.

As nations commit to net-zero carbon targets, adaptive materials can play a central role. They're not a complete solution, but they're a crucial tool. Chameleons have perfected adaptation over millions of years of evolution.

By learning from nature and engineering smart materials that respond to their environment, research groups worldwide, including at the University of Melbourne, are advancing these materials from concept to application.

The path from lab to large-scale deployment is underway, driven by urgent climate challenges and growing demand for smarter infrastructure.

We're fundamentally changing how buildings and infrastructure interact with the world around them, one degree at a time.

Provided by University of Melbourne