Hydrogel windows to lower the temperature in buildings
With global warming starting to take effect, the temperature can rise very high during the summer. But using air conditioning systems is not always practical with all the energy they consume. In Chinaresearchers have come up with a new idea for solve the problem of temperature increase in buildings. They replaced the window panes with special glass coated with hydrogel. This glass is capable of blocking heat from the Sun while allowing light to pass through.
Generally, standard glass is designed to allow visible light to pass through to illuminate a room. But he allows near infrared radiation to pass sunlight while preventing mid-infrared radiation from escaping of the room. This phenomenon is used to warm a room of a buildingbut during the summer it causes a significant increase in temperature.
The scientists of Wuhan University have tested many materials to try to counteract this effect of glass.
The hydrogel as a solution
In an attempt to combat the problem of rising indoor temperatures, researchers have developed a hydrogel coating with a thickness of a few millimeters. This coating was designed to better reflect near infrared radiation coming from outside while allowing mid-infrared radiation to exit.
The principle used by scientists is that which says that visible light photons can penetrate water over a distance of 1m while near infrared photons can only advance a few millimeters. As the hydrogel is made primarily with water, this makes it a practical selective barrier.
Test results
During the tests, the scientists discovered that the glass coated with hydrogel emitted up to 96% of infrared light straight into space. Indeed, the radiations of these wavelengths are not blocked by the atmosphere. This process would cool the interior of a building as radiant cooling systems would. Ordinary glass is known to emit about 84% of this radiation.
You might think that glass coated with hydrogel is more opaque than ordinary glass, but tests have shown that, on the contrary, it allows a little more light to pass through. It can let through up to 92.8% of the visible light in a room, compared to 92.3% for ordinary glass.
To better assess the effect of using the hydrogel coating, the scientists used the special glass on house models measuring 20 * 20 * 20 cm. These models had thick insulated walls and a large window. The measurements showed that the glass with the hydrogel reduced the temperature inside by 3.5°C.
The researchers thus believe that the hydrogel is an inexpensive solution for lowering the temperature in buildings while saving energy.
SOURCE: newatlas
