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X-Tile is a roof tile that can reflect light and heat by turning white above 20°C and absorb it, by turning black below 20°C, subsequently cooling or heating a home.

What it does

Climate change is a problem aggravated by electrical air conditioners. X-Tile allows buildings to self-regulate temperature by changing its light absorption and reflection properties of the roof.

Your inspiration

Since I was a child, I have wanted to help “save the world” from an ecological point of view. For this reason I chose a university course oriented towards sustainability in which I was able to design different solutions for energy saving. The idea for X-Tile came from reading news about preserving glaciers by covering them with huge white geo-textile blankets to reflect the light and heat to prevent them from melting. The idea solidified from observing a mug which turned from black to white when pouring hot drinks inside. So I decided to apply it to a ceramic tile designed to isolate and dissipate heat.

How it works

Normal tiles are made of terracotta, a cheap material which absorbs a lof of heat. They can also be made of ceramic, which if white, can reflect much of the sunlight that would otherwise heat the roof and therefore the house. On the contrary, in winter it would be ideal for it to be black to absorb light and transform it into heat. After cooking the clay, we have to apply a layer of black thermo-chromatic paint and a layer of white one. The black layer becomes transparent above 20 degrees, letting light reflect on the underlying white layer. The paint is permanently fixed to the tile with a transparent glossy enamel, which becomes stable after cooking it for a second time. We are still testing another permanent fixing of this paint which has to last for years without changing its own characteristics. The tile design is created to isolate from heat/cold with an internal ventilated chamber dissipating heat with some slats.

Design process

At the beginning the concept involved the adoption of tiles with moving parts, they were coloured on one side of white and on the other side they were black. As the temperature changes, it would have been necessary to find a mechanical way to rotate the tile surface. However, this would have implied some complex systems of electric, or worse, manual movement. Furthermore, these mobile parts would have represented some maintenance problems and dirt accumulation. It was important to find a way to automate the colour change process without manual interventions and consuming energy. The use of an e-ink (electronic ink) has also been considered, like the one used by e-readers, which, due to tiny titanium bioxide spheres, can change colour from white to black using a small amount of energy obtained using a small photovoltaic panel. Yet this would have been an expensive solution for an entire roof. A thermo-chromatic paint, as the one used on commercial mugs, is for now the ideal solution to achieve this purpose. The shape of the tile was also characterised, which is inspired by a computer heat sink and is able to rapidly disperse the heat. This form can be easily produced industrially by extrusion.

How it is different

The project is unique because it aims to improve the insulation of the houses by adjusting itself without external intervention as if it were a “smart” product and integrating various solutions inspired by different contexts such as the automatic color change (e.g. commercial mugs), the dissipation (e.g. air engine/motor with fins) and insulation with a ventilated cavity (e.g. empty bricks). It is therefore given as a set of static solutions which do not require any other intervention after the installation keeping, at the same time, the constructive simplicity typical of industrial production. X-Tile is a tile created with the only purpose of improving the energy sustainability of the houses with three different solutions in the same product. Adopted by everyone, it would contribute a lot in reducing the global CO2 emissions from heating and cooling buildings and making warmer cities more habitable. Currently, there are no similar products on the market.

Future plans

The next steps are to verify the effective duration of the thermo-chromatic properties of the tiles over the years, in addition to a more precise estimate of the production costs. At the moment the cost is much higher than the one of a normal tile due to the double firing and for the special paint adopted. Further developments will evaluate solutions to reduce these costs in order to guarantee an effective mass adoption of the product. In particular, other experiments will be carried out using titanium dioxide, which, in addition to being able to easily change colour from white to black, (e.g. e-readers), can guarantee a long life.


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