In 2019, University of Maryland researchers stripped lignin from wood; the resulting cooling material stayed 12°F cooler than natural wood in an Arizona test

In 2019, a team of materials scientists published their findings in Science in a paper titled A radiative cooling structural material. The study explored how engineered wood could be designed to reflect sunlight and release heat, offering a possible passive approach to cooling buildings.

The researchers also tested the material outdoors on a farm in Arizona. According to the University of Maryland's 2019 account of the work, the treated wood stayed an average of 12°F, or about 6.7°C, cooler than natural wood when exposed to sunlight. The result showed how changing wood's structure could affect the way it handles heat without relying on electricity.

The process began with lignin, a component that gives wood much of its colour and contributes to its structural properties. Materials scientist Liangbing Hu and his colleagues removed most of the lignin while preserving the wood's basic structure, leaving a pale material made largely from cellulose. The team then compressed the treated wood to improve its mechanical strength and added a water-repellent coating to make it more suitable for outdoor use.


The treatment changed how the material interacted with sunlight and heat. Its bright surface reflected a large portion of incoming solar energy, while its engineered structure helped it emit thermal radiation as infrared energy. This process, known as passive radiative cooling, can remove heat without electricity, fans or other powered equipment.

Why the material stayed cooler

The cooling effect came from controlling both incoming sunlight and outgoing heat. Natural wood can absorb solar energy and warm up, while the engineered material was designed to reflect much of that energy instead. At the same time, its structure was able to emit thermal radiation, allowing heat to escape from the material's surface.

The Arizona test showed that this combination could work outside laboratory conditions. When exposed to sunlight, the treated wood remained an average of 12°F cooler than natural wood exposed to the same conditions.

The material's microscopic structure was important to its optical properties. The researchers engineered the wood so that the cellulose framework could interact with incoming light in a way that increased solar reflectance, while also supporting the emission of thermal radiation. Compression strengthened the material, and the water-repellent coating helped protect it from moisture.

Could cooling wood reduce building energy use?

The potential application is straightforward: a building surface that reflects more sunlight and releases heat could reduce the amount of heat entering a structure. That could be useful in places where buildings require substantial cooling during hot weather.

The University of Maryland's analysis also examined the potential effect on cooling energy in apartment buildings across different US climate zones. It found that the potential savings varied by location and building characteristics, with hotter cities such as Phoenix and Honolulu among the places where the material could offer greater benefits. The analysis estimated that using the material in certain building applications could reduce cooling energy use, particularly when applied to older buildings.

The researchers also reported a high strength-to-weight ratio for the engineered wood, suggesting that its potential was not limited to managing heat. Its mechanical properties were another part of the work examining whether the material could eventually be useful in construction.

The 2019 study demonstrated the material's cooling performance and explored possible building applications, but further development would be needed before it could become a widely available construction product. The research instead showed how a familiar plant-based material could be engineered to perform a different thermal role.

For hot climates, that could make cooling wood worth exploring for applications such as roofing and exterior building surfaces. Rather than relying entirely on powered systems to remove heat after a building warms up, the material offers a way to reduce solar heat absorption and release some heat directly from the surface.