Wood windows cooler than those of glass

New York: Windows made of transparent wood could provide more even and consistent natural lighting and a cooler ambiance, a study says.

The researchers showed that their transparent wood provides better thermal insulation and lets in nearly as much light as glass, while eliminating glare and providing uniform and consistent indoor lighting. The findings advance earlier published work on their development of transparent wood.

The transparent wood lets through just a little bit less light than glass, but a lot less heat, said lead author of the new study Tian Li from University of Maryland, College Park in the US.

"It is very transparent, but still allows for a little bit of privacy because it is not completely see-through. We also learned that the channels in the wood transmit light with wavelengths around the range of the wavelengths of visible light, but that it blocks the wavelengths that carry mostly heat," said Li.

The team's findings, published in the journal Advanced Energy Materials, were derived, in part, from tests on tiny model house with a transparent wood panel in the ceiling that the team built. 

The tests showed that the light was more evenly distributed around a space with a transparent wood roof than a glass roof.

The channels in the wood direct visible light straight through the material, but the cell structure that still remains bounces the light around just a little bit, a property called haze.

This means the light does not shine directly into your eyes, making it more comfortable to look at. 

Transparent wood still has all the cell structures that comprised the original piece of wood. The wood is cut against the grain, so that the channels that drew water and nutrients up from the roots lie along the shortest dimension of the window. 

The new transparent wood uses theses natural channels in wood to guide the sunlight through the wood.

As the sun passes over a house with glass windows, the angle at which light shines through the glass changes as the sun moves. 

With windows or panels made of transparent wood instead of glass, as the sun moves across the sky, the channels in the wood direct the sunlight in the same way every time, the researchers said.