Researchers from the City University of Hong Kong have developed a multifunctional coating for buildings that can reduce surface temperatures by up to 9.5 °C below ambient and generate energy from rain.
This “smart skin” reflects more than 95% of solar radiation and expels heat through infrared radiation, making it a key tool against the urban heat island effect.
Inspired by the air plant Tillandsia, capable of capturing moisture in extreme environments, the technology is applied as a paint on facades and roofs, facilitating its integration into existing buildings without the need for costly renovations.
Main Functions
- Passive cooling: reflects solar radiation and reduces surface temperatures.
- Electric generation with rain: raindrops produce charges capable of powering wireless sensors or low-consumption devices.
- Architectural protection: acts as a resistant layer against adverse weather conditions.
Applications in Smart Cities
The energy obtained from rain, although modest, can power sensor networks for:
- Environmental monitoring: air quality, humidity, and temperature.
- Structural control of buildings.
- Smart energy management.
Within the framework of smart cities, this innovation allows for the use of natural phenomena to reduce costs and improve urban sustainability.
Advantages over Conventional Technologies
- Simple application: used as paint, avoiding complex installations.
- Scalability: can be implemented in existing buildings, key for energy rehabilitation.
- Complementarity: integrates with solar panels, energy storage, and hydrogen systems, forming part of distributed solutions for future cities.
Green Hydrogen and Cost Reduction
The same team is also working on a green hydrogen production system that replaces costly materials with accessible elements, which could accelerate the adoption of this energy source in industrial sectors that are difficult to electrify.
Global Impact and Urban Future
The vision proposed by these developments is especially relevant for large urban areas: facades and roofs could cease to be passive elements and become multifunctional energy infrastructures. Instead of occupying new land to install equipment, the already built space would be utilized.
The cities of the future will likely combine multiple distributed solutions:
- Solar panels.
- Cooling materials.
- Smart sensors.
- Hydrogen systems.
No single technology will solve the current climate challenges, but the sum of innovations like this can bring about profound changes in the way we inhabit and manage our cities.
Hong Kong’s “smart skin” demonstrates how architecture can become an active ally against climate change.
With its ability to cool, generate energy, and protect buildings, this innovation paves the way for more resilient, sustainable cities ready to face heat waves and the energy transition.
