“This is the first time that a nanostructure has been combined with a thermochromic coating. The bio-inspired nanostructure amplifies the thermochromic properties of the coating and the net result is a self-cleaning, highly performing smart window,” said Dr. Ioannis Papakonstantinou of UCL.
The University College London (UCL) developed a new type of window. They call it smart window. In fact, it is not the entire window which is smart. To be precise, the focus is on the window glass. The scientists improved the glass extensively with a pencil-like engraved nanostructure onto the glass and demonstrated three benefits with their prototypes making the glass ‘smart’.
Due to the applied nanostructure engraved onto the glass, their smart window (glass) has anti-reflective properties. They compare it with the eye of a moth which looks matt and black to protect against predators. The advantage is that less than five percent of the internal light in a room can be reflected. This increases the comfort for building occupants. Other prototypes like vanadium dioxide coated, energy-saving windows achieve 20-30 percent.
The engraved nanostructure makes the smart window (glass) resistant to water. Hitting rain drips off easily and rolls over the surface in the form of spherical droplets. At the same time, the raindrops pick up dirt and carry it away. Normal glass is different. Raindrops cling to the surface before they slide down more slowly. After drying, one can see their marks.
The smart window (glass) is coated with a very thin film of vanadium dioxide. The layer is 5 – 10 nanometres thick. According to EPSRC (Engineering and Physical Sciences Research Council), it stops thermal radiation and prevents heat losses during cold seasons. During hot periods, it reduces the cooling demand because less infrared radiation is entering the building. The use of vanadium is a real advantage compared to other coatings. Vanadium dioxide is not expensive. It is an abundant element and occurs naturally in about 65 different minerals.