Cooling or air conditioning is more complicated than heating. According to the US Department of Energy, heating and cooling systems trigger over half a billion tons of carbon dioxide in the atmosphere each year. Also most of our buildings made of concrete, whose production is an important source of carbon dioxide emissions. And when it is clear, heating and cooling buildings become a major energy source.
A good way to reduce the amount of cooling that a building needs is to make sure it reflects infrared radiation. Passive radiative cooling materials are designed to make this extremely good.
Now, a new type of wood that radiates heat in space can offer some relief. The material, if used on the exterior of the building, can release a building temperature as much as 10 ° C and reduce the cooling cost as much as 35%.
Liangbing Hu, a material researcher at the University of Maryland and his colleagues created this material by removing the lignin from natural wood with hydrogen peroxide.
Perhaps the high-tech wood houses can help us stay cool and reduce carbon dioxide emissions by reducing the energy used in air conditioning.
High-tech cooling wood
Lignin is part of the cell walls of trees, which act as an adhesive that holds the straw strings together. Lignin is a strong emitter of IR light.
The layer removed this from the wood by simply soaking the base wood in a solution of hydrogen peroxide, which normally cut long lignin molecules into small fragments. The fragments diffuse out of the solution and can be washed away. The team then used a hot press, an industrial screw to manufacture wood composites, to compress the remaining cellulose and hemicellulose components together. The result was a constructed wood with eight times the strength of natural wood.
In addition, cellulose in the wood reflects visible light and absorbs only very low levels of near infrared light. It simply means that the cooling wood reflects most of the sunlight components directly back into the environment.
As a result, a building made of this material would barely transmit any heat indoors. The team also found that the material can absorb heat produced indoors, which is emitted at another wavelength range to sunlight. During cooler nights, the wood helps to let the heat out, making it useful day and night.
It can reduce air conditioning costs:
If this material was applied to the buildings in the buildings in the warm climate, the passive cooling effect could reduce air conditioning costs by as much as 35%, the researchers reported in the journal Science.
Hu says the cooling wood is very tight and has a tensile strength of about 404 megapascals, making it 8.7 times stronger than natural wood and comparable to metal structures, including steel.
But since the cooling wood limits the heat from the sun from coming indoors, it can add additional heating costs during the winter. Therefore, Hu says that the material is best suited for warm areas with long summers and short winters.
The multifunctional, scalable cooling material allows for future energy-efficient and sustainable building applications, allowing for a significant reduction in carbon dioxide emissions and energy consumption.