Matthew Wood, September 9, 2016

What if your wall was actually a window?

That?s not an existential question. It?s the basis of a project by a team from the University of Maryland, which aims to make a transparent wood product that could also serve as a window. The result could have an incredible impact on the way we view lighting and heat our homes.

?We are trying to demonstrate the energy efficiency of this material,? says Tian Li, the lead author of a new study. ?I was looking at this wood and thinking there was unique optical property. We were looking at it and found out it can kind of function as a sunlight guide.?

Li?s team, led by Maryland Department of Materials Science and Engineering head Liangbing Hu, recently had their findings published in the journal ?Advanced Energy Materials.? It describes the process to treat the wood in order to make it as close to transparent as possible, as well as the favorable properties for insulation and heating of buildings.

The process involves bleaching the wood of all the lignin, which gives it the brown color and strength. Then it is soaked in epoxy, which adds strength while making the wood more clear.

?We have been working on cellulose materials for the past 5 years,? Hu said. ?It is one of the out-of-the-box ideas that has us really excited.?

Much of the research started with paper materials, then branched out into larger objects.

?It turns out the structure [of the wood] can be kept there,? Li says. ?There?s very little damage to it.?

The improvements for home heating and energy consumption could be monumental. It starts with the basic physics of glass windows versus wood. With a window, you have concentrated energy and light, which is then diffused through the small pane of glass. This process produces diffused light inside and, perhaps more importantly, rejects a good portion of the energy from the sun. With the wood structure, light is emanated more evenly, resulting in a more constant temperature throughout the inside of a building.

?The wood is a better thermal insulator than glass,? Li explains. The glass windows are the problem. That?s why you have all these air conditioners on. The heat goes through in the summer and it goes out in the winter.?

Creating more natural light within homes also has benefits.

?It creates a very uniform lighting,? Li says. ?It will lower electrical bills. Natural lights are the best. They can actually affect the mood of the occupants. They are much more comfortable and consistent.?

In order to test their theories, the Maryland team actually built a miniature house with a transparent wood panel in the roof. Testing showed a much more even dispersion of light throughout the house.

Li says, in addition to being waterproof, their wood has stronger chemical properties than glass, meaning it could stand up better to the rigors of weather.

?It?s much tougher, greater chemical properties than glass,? Li says. ?It would only be one break, instead of glass with all these sharp pieces everywhere.?

While the team has progressed in the nearly two years they?ve been working on the project, Hu said it will still need some time before hitting the consumer market. ?Probably around four or five years. We are working to improve some of the different properties.?