A new Israeli-Singaporean development makes it possible to prevent solar radiation from entering the home through the window - without damaging the view
The winter weather system of the last few weeks caused many to lock themselves in the house (sometimes with the help of a positive corona test), next to the air conditioner, furnace or radiator that work almost non-stop. On days like these we long for a little sun to come in through the window and warm the house - and it's easy for us to forget that in the summer months we escape from its hot rays.
In a new study Conducted in Israeli-Singaporean cooperation opens a smart window, which will be able to mitigate the temperature crisis in all seasons of the year. The window makes it possible to block the entrance of the sun's radiation with the push of a button, thus controlling the amount of heat that enters the house through the windows, and reducing the need for air conditioning - all this without harming the view that overlooks us.
according to US Department of Energy, windows are a main source of necessary heat loss in winter and unwanted heat entry in summer in buildings. In the modern era, we "solve" the problem with air conditioners, but each push of their remote control buttons increases our electricity bill - and causes additional emissions of greenhouse gases when fossil fuels are burned in the power plants, thus worsening the climate crisis (and the worsening of the extreme temperatures for which we turned on the the merger in the first place).
However, completely blocking sunlight (for example by a curtain or blind) has its own disadvantages. The use of sunlight enables savings in spending energy on lighting, and exposure to the landscape through the windows includes significant advantages that should not be underestimated: Hundreds of scientific studies Pointing out the positive effect that exposure to nature has on our physical and mental health - exposure from a distance also provides a positive and healing effect.
Using "smart" windows (like the new development) does indeed require energy - but in a small amount. In fact, it is possible to operate a 140 square meter window that operates with such technology for less than the energy required to light a single 60 watt lamp.
Insulation on demand
The new study was led by Prof. Alfred Tuck from Nanyang University in Singapore, in collaboration with the Israeli researchers Prof. Shlomo Magdessi, head of the 3D printing center at the Center for Nanotechnology of the Hebrew University, and Prof. Daniel Mandler from the Institute of Chemistry at the Hebrew University, who deals with electrochemistry, as part of a joint research program of researchers from Israel and Singapore, and it was carried out and financed within the framework of the CREATE program which belongs to the National Research Foundation of Singapore.
The new invention includes glass that is coated with a special material, in which a momentary electric current is produced at the push of a button that allows or blocks the entry of the sun's heat - and this almost without affecting its degree of transparency. "These are electrochromic windows - that is, windows that change the radiation they absorb using electrical voltage," Magdessi explains. "In the case of this development, it involves the absorption of infrared radiation (heat radiation, Y.S.), so that in the winter it can be allowed to enter - and in the summer it can be blocked, thus saving on air conditioning costs." Infrared radiation is outside the range that humans are able to see, so blocking it does not harm the view that is visible to us through the window.
The new glass, developed and tested under laboratory conditions, allows blocking of 70 percent of the sun's infrared radiation, while maintaining 90 percent transparency for the solar radiation that is in the range that humans are able to see. In this way, the new development is different from most of the other electrochromic windows that exist today, which are only capable of making the frames dark - which damages the view seen from the window.
Like a smartphone screen
To achieve this result, the researchers created a glass coating that is made up of several layers. First, the glass was covered with a beehive-like structure. Electrically conductive materials based on the oxide of the metallic elements tungsten and tin, which is refined with the metals neodymium and molybdenum (that is, to which these metals were added in a minimal concentration for the purpose of increasing the electrical conductivity), were introduced into the spaces in this structure, the use of which sets the development apart from other electrochromic windows (which are used only in tungsten oxide) - they are actually able to change their state and turn almost completely sealed off from the sun's heat radiation. Finally, a solution containing ions (electrically charged particles) of lithium was also added to the structure, together with electrodes made of a transparent material that conducts electricity. "The electrode is similar to the glass of a smartphone screen, which also contains a transparent conductor," Magdessi explains. "When an electric voltage is applied, the ions come out of the solution and enter the particles of the solid material that combines the neodymium and molybdenum, thus changing its light absorption properties, because substances absorb light according to their electronic structure. Another application of a reverse voltage results in the change of the material back."
According to the researchers, about a third of the electricity consumption in a modern city is used for intrastructural lighting and air conditioning, so this is a development with huge energy saving potential. At the same time, in the meantime the selective glass exists only as a preliminary experiment in the laboratory. "It will take several more years before we see windows like this in houses," Magdessi estimates.
Energy management through the window
Green building experts emphasize that proper pre-planning of the building before its construction can lead to significant energy savings. Intelligent shading must be produced and the building and the windows must be placed so that the penetration of the sun is increased in the winter and reduced in the summer - according to the sun's path that changes throughout the year. In this way, the wind directions in the area of the building must also be taken into account, and strive to achieve natural ventilation by placing opposite openings in each space - preferably in the direction of the wind flow. All of these are possible to perform without incorporating innovative technologies.
The use of insulated building materials may be another significant factor when it comes to saving energy, but it seems that even in our hot country many of the designers of tall office buildings ignore the high energy costs that are required for environmental protection, and these buildings are often built with glass envelopes that, although they provide a modern side view and a panoramic view of the landscape, but allow The sun's heat can penetrate from all directions all the time and create a greenhouse effect inside the building, increasing the constant need to operate air conditioning systems. Many of these windows do not open at all, and thus do not allow for the circulation of air that is important for the climate (and to prevent infection with airborne diseases).
It is possible that in the coming years, developments such as the smart glass that enables heat filtering at the push of a button will be able to balance the uncompromising aesthetic demands, and will allow a more sustainable and considerate conduct of the electricity bill and the environment. In the meantime, Magdesi worked on additional upgrades for the glasses of the future, in a joint venture with Prof. Lioz Etgar, also from the Institute of Chemistry at the Hebrew University, who is involved in the development of solar cells. The two are developing semi-transparent solar cells, which could enable energy production through window surfaces. "Our ambition is to use them in the glass shell of a building, as for example in modern office towers," says Magdessi. "In the future, it may be possible to combine these two technologies together. Thus, energy saving is combined with energy production - and everything is under more correct energy management, which we need now and if we need it in the future as well."
And for those of us who don't want to wait to get a reduction in the electricity bill, you should take my steps Green renovation Various simple ones: for example, improving the sealing of the windows (which prevents heat leakage in the winter), adding a layer of insulation to the walls or ceiling and using a fan instead of an air conditioner. Each and every one of us can take these steps at home today.
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