New solar technology to change the future of interior lighting

University of Cincinnati researchers Anton Harfmann and Jason Heikenfeld have developed a new technology, SmartLight, that might change the future of how building interiors are brightened.

A typical photovoltaic array loses most of the sun’s energy when it gets converted into electricity. But with SmartLight, Harfmann says the sunlight channelled through the system stays, and is used, in its original form. This method is far more efficient than converting light into electricity then back into light and would be far more sustainable than generating electric light by burning fossil fuels or releasing nuclear energy.

The technology could be applied to any building - big or small, old or new, residential or commercial. But Harfmann and Heikenfeld believe it will have the greatest impact on large commercial buildings. The US Department of Energy’s Energy Information Administration shows that 21% of commercial sector electricity consumption went towards lighting in 2011. Harfmann calls the energy demand for lighting in big, commercial buildings “the major energy hog”, and he says energy needed to occupy buildings accounts for close to 50% of the total energy consumed by humans.

SmartLight could help shift that energy imbalance. It works like this: A narrow grid of electrofluidic cells which is self-powered by embedded photovoltaic is applied near the top of a window. Each tiny cell - only a few millimetres wide - contains fluid with optical properties as good or better than glass. The surface tension of the fluid can be rapidly manipulated into shapes such as lenses or prisms through minimal electrical stimulation - about 10,000 to 100,000 times less power than what’s needed to light a traditional incandescent bulb. In this way, sunlight passing through the cell can be controlled.

The grid might direct some light to reflect off the ceiling to provide ambient room lighting. Other light might get focused toward special fixtures for task lighting. Yet another portion of light might be transmitted across the empty, uppermost spaces in a room to an existing or newly installed transom window fitted with its own electrofluidic grid. From there, the process could be repeated to enable sunlight to reach the deepest, most "light-locked" areas of any building. And it's all done without needing to install new wiring, ducts, tubes or cables.

As for switching, Harfmann envisions a workplace where physical light switches join other anachronistic office equipment like mouse pads or bulky CRT monitors. Plans call for SmartLight to be controlled wirelessly via a mobile software application. So instead of manually flipping a switch on a wall, a user would indicate their lighting preferences through an app on their mobile device, and SmartLight would regulate the room's brightness accordingly. SmartLight could even use geolocation data from the app to respond when a user enters or leaves a room or when they change seats within the room by manipulating Wi-Fi-enabled light fixtures. 

A user could control SmartLight through a mobile app. "SmartLight would be controlled wirelessly. There would be no wires to run. You wouldn't have light switches in the room. You wouldn't have electricity routed in the walls," Harfmann says. "You would walk into a room and lights would switch on because your smartphone knows where you are and is communicating with the SmartLight system."

But what happens at night or on cloudy days? That's where SmartLight's energy storage ability comes in. On a typical sunny day, sunlight strikes a facade at a rate that's often hundreds of times greater than what is needed to light the entire building. SmartLight can funnel surplus light into a centralised harvesting- and energy-storing hub within the building. The stored energy could then be used to beam electrical lighting back through the building when natural light levels are low. The SmartLight's grid is so responsive – each cell can switch by the second – it can react dynamically to varying light levels throughout the day, meaning office lighting levels would remain constant during bright mornings spent catching up on email, stormy lunch hours spent eating at your desk, and late nights spent reviewing the budget.

With such potential for energy storage, a building's electrical network also could tap into the centralised hub and use the stockpiled energy to power other needs, such as heating and cooling. And if centralised collection of surplus sunlight isn't possible inside some existing structures, the light could even be sent straight through a building to a neighbouring collection facility.

Heikenfeld says much of the science and technology required to make the Smart Light commercially viable already exists. He and Harfmann have begun evaluating materials and advanced manufacturing methods. The only thing missing at this point is enough funding to create a large-scale prototype which could call the attention of government or industry partners interested in bringing SmartLight to market.

"We're going to look for some substantial funds to really put a meaningful program together," Heikenfeld says. "We've already done a lot of the seed work. We're at the point where it would be a big, commercially driven type of effort. The next step is the tough part. How do you translate that into commercial products?"