New wood could lower building temperature and reduce cooling costs

Cooling or air conditioning is more complicated than heating. According to the US Department of Energy, heating and cooling systems annually release more than half a billion tons of carbon dioxide into the atmosphere. In addition, most of our buildings are concrete, the production of which is a major source of carbon emissions. Once this is done, the heating and cooling of buildings become an important energy sink.

A good way to reduce the amount of cooling a building needs is to make sure the infrared radiation is reflected. Passive radiative cooling materials are designed to do extremely well.

Now, a new type of wood that gives off heat in the space could offer some relief. The material, if used outside a building, can lower the building temperature up to 10 ° C and reduce cooling costs by up to 35%.

Liangbing Hu, a materials scientist at the University of Maryland and his colleagues, created this material by removing "lignin" from natural wood using hydrogen peroxide.

High-tech wood houses could help us stay cool and reduce carbon emissions by reducing the energy used for cooling.

High-tech cooling wood

Lignin is a component of the cell walls in the trees, which acts as an adhesive holding the straw strands together. Lignin is a powerful emitter of infrared light.

The team removed this material from the wood by simply soaking the American linden in a solution of hydrogen peroxide, which normally chopped long lignin molecules into small fragments. The fragments diffuse out of the solution and can be washed. The team then used a hot press, an industrial vice for the manufacture of wood-based composites, to compress the remaining components of cellulose and hemicellulose. The result was an engineered wood eight times stronger than natural wood.

In addition, cellulose in wood reflects visible light and absorbs only very low levels of near infrared light. It simply means that the cooling wood reflects most components of the sunlight to the environment.

As a result, a building made from this material would hardly transmit heat to the interior. The team also found that the material can absorb heat generated inside, which is emitted at a range of different wavelengths from that of the sun. During cooler nights, the wood helps release heat to the outside, making it useful day and night.

This could reduce air conditioning costs:

If this material was applied to the exterior of buildings in hot climates, the passive cooling effect could reduce air conditioning costs by up to 35%, the researchers said in the journal Science.

According to Hu, the cooling wood is very dense and has a tensile strength of about 404 megapascals, which makes it 8.7 times stronger than natural wood and comparable to metal structure materials, including including steel.

But as the cooling wood prevents the heat of the sun from getting back inside, it could therefore result in additional heating costs in the winter. Therefore, Hu says that the material is best suited to hot areas with long summers and short winters.

This multifunctional and scalable wood-based cooling material is promising for future sustainable and energy-efficient building applications, enabling a substantial reduction in carbon emissions and energy consumption.