Researchers have developed a "cooling wood" that reflects sunlight and radiates heat from a building, lowering a home's electricity consumption.
A team at the University of Maryland and the University of Colorado Boulder gave the trusty old wood an upgrade by removing one of its two main components, a polymer called lignin. Lignin acts as a glue holding together the molecules of wood's other component, the cellulose, but it also absorbs infrared light and, therefore, warms up under the sun.
The resulting wood is then compressed, creating a material that is stronger than its natural counterpart. The researchers described the cooling wood in a paper published in Science.
Giving Wood A Makeover
After the researchers had removed the lignin, they ended up with a very pale piece of wood that was made up solely of cellulose fiber. Next, they compressed it to make it durable and then added a hydrophobic compound to make it resistant to water.
The result was a bright white material that can be used to line the roof in order to remove heat inside the building.
"The processed wood uses the cold universe as heat sink and release thermal energy into it via atmospheric transparency window," stated Tian Li of the University of Maryland's Department of Material Science and one of the co-authors of the study. "It is a sustainable material for sustainable energy to combat global warming."
The researchers claimed that the resulting material is stronger than steel and damages less easily than normal wood.
Using Cooling Wood For Energy-Efficient Homes
The researchers took their cooling woods for a test on a farm in Arizona. They reported that the cooling wood had an average of 5 to 6 degrees Fahrenheit cooler than the ambient air around it, even during the warmest part of the day. They also said that the material was 12 degrees Fahrenheit cooler than natural wood.
In addition, the team calculated how much energy consumers would save by using cooling wood in apartment buildings. They estimated that the material would, on average, save 20 percent on cooling costs. Cities in Phoenix and Honolulu, where the climate is warmer, would save the most energy.
"It is interesting that the same material that releases heat upon combustion can be used for cooling, offering new opportunities in green buildings," added Orlando Rojas, a professor in the Department of Bioproducts and Biosystems at Aalto University.