Smart windows are the logical next step in the evolution of home design. Basically, the idea behind them is that instead of adding blinds or curtains to windows, so as to control the amount of heat or light entering the home (or for privacy) the windows would already have this function built in. Sounds futuristic, but a team of researchers at Harvard’s John A. Paulson School of Engineering and Applied Sciences have found a simple and quite affordable way to achieve it.

Their method does not involve an electrochemical reaction for the windows to turn from clear to opaque, as was the case with most of the smart window solutions to date. The smart window they developed is constructed using a sheet of glass or plastic, which is sandwiched between two transparent elastomer sheets that were sprayed with silver nanowires. The window is clear since these nanowires are too small to scatter light. Yet with an application of an electric voltage they have the capacity to turn the window opaque.

In more technical terms, applying voltage energizes the nanowires causing them to move toward each other, which causes the soft elastomer to be deformed. Since the nanowires aren’t distributed evenly across the surface, the deformation is uneven too, and this makes the light scatter and turns the glass opaque

Users would also be able to control the level of opacity, since it is dependent on the amount of voltage applied. Lower voltage would cause the windows to turn slightly cloudy, while high voltage would turn them completely opaque.

The researchers are currently in the process of refining their design. They’re primarily focusing on making the elastomer coating thinner, which would mean that lower voltages would be needed to make the windows opaque. This would make the technology suitable for use in homes and offices.