new windows that save on air conditioning costs and are also self-cleaning

With the arrival of warmer temperatures in spring and summer, the days become longer and more pleasant, but this also means protecting your homes with blinds and curtains. This DIY trick, which many foreigners learn upon arrival in the country, has the disadvantage that it reduces the amount of natural light entering the interior, forcing the use of artificial light. What if there was a solution to Save on air conditioning while enjoying natural light and privacy? This is what researchers from Germany tried to group into a single material.

In Spain you can find solutions that will transform the windows of your home in a few minutes, providing greater privacy without loss of light, and at a very low price. You can also rely on electrochromic (EC) glasses, which have been used in homes, offices and other indoor environments for years: they promise on-demand privacy while consuming little electricity. Well, this material can block light or change color through electrical discharges, although these two examples do not reduce heat and require regular cleaning.

Researchers from the Institute for Microstructure Technology (IMT) in Karlsruhe have developed a material that will make it possible to create windows that can regulate the indoor microclimate. without the need for additional energy, do not lose luminosity and are purified like a lotus leaf. It is a polymer-based metamaterial with micropyramidal surface superstructures, PMMM (microphotonic multifunctional polymer-based metamaterial).

Less heat, more light

Having natural light is always preferable to using artificial light, both in terms of economic savings and the health benefits it provides. But a home with large windows, such as a greenhouse, is also exposed to heat caused by rays passing through the glass.

Unlike traditional glass, this material manages to scatter the incident light in several directions instead of transmitting it directly. This means softer lighting that is pleasing to the eye and reaches every corner of the room. In addition, from the outside, this effect implies privacy, since people outside the house cannot see the interior space.

All these advantages are due to the composition of the surface. This metamaterial consists of micro-sized pyramids. These structures are made of silicone and They are one tenth the thickness of a human hair.

The roughness that forms this community of micropyramids minimizes losses due to reflection, since light upon contact with them is subject to multiple reflections, as if they were hundreds of mirrors. This translates to 95% transmittance for visible light and diffuse transmission 73%, the study authors noted.

Once developed, the research team tested the qualities of their invention both inside and outside the KIT campus laboratory. Light transmittance, light scattering, reflectance, self-cleaning ability and cooling efficiency were tested using advanced spectrophotometry.

The test result was a cooling of 6 degrees Celsius compared to room temperature. In addition to the above data, when used in greenhouses, it is assumed that the metamaterial increases photosynthesis efficiency by 9% compared to glass roofs. The research team also claims that PMMM is made from environmentally friendly and commercially viable polymer materials.

Self-cleaning

The lotus flower is the queen of any pond, a plant that lives in an aquatic environment and at the same time has the ability to repel water, which has long fascinated the scientific community.

Its leaves have what is called hydrophobicity. When water comes into contact with its surface, the droplets glide without penetrating or saturating the leaf, keeping it afloat on the water surface, apart from its shape. This phenomenon is associated with the roughness of the sheet and its chemical composition.

Thanks to this knowledge, people were able to reproduce this quality on a variety of surfaces: from brick, glass to clothing. Both water and other oily liquids slide off these materials without leaving a trace. Now it’s the turn of these windows.

“Taking advantage similarity of micropyramids with microcones on lotus leaves, “Our metamaterial also has excellent superhydrophobic properties, which facilitates self-cleaning,” explains the team. In a study published in the scientific journal Nature, the researchers included several examples of images of dust that disappeared when water was applied. to that.

As water droplets slide across the glass, they carry other particles in their path, such as dust, and remove dirt. This way, these future windows can be kept clean without the need for intervention, in the rain or at least with splashes of water thanks to a garden hose.