Designing buildings with large glass façades enhances the visual and environmental comfort of their occupants, and allows natural light to be enjoyed almost all day long.
However, the direct sunlight on these premises during the summer months leads to considerable increases in indoor temperatures, unless the glass on these façades have the suitable properties and treatments for preventing excessive heating. A similar problem occurs in winter, when the walls and objects in a glass room absorb the cold from the outside and cool the premises more than is desirable. Thus, maintaining a comfortable temperature in a glass room, both in winter and summer, requires having climate control systems that increase the power consumption of the household or workplace.
For the above reasons, in these buildings obtaining a comfortable and suitable temperature in summer or winter requires more energy consumption than in buildings made with other materials, particularly due to the use of air conditioning and heating, which increase atmospheric CO2 emissions.
To promote and support energy saving and help to slow down climate change, glass manufacturers are applying the latest technological breakthroughs to control the entry of solar energy into rooms with large glass surfaces, preventing temperature increases beyond comfort levels due to the “greenhouse effect”.
The field of nanotechnology applied to glass provides solutions of great interest from the point of view of energy savings, as it allows controlling the solar radiation that enters the building, as well as the visibility and privacy of occupants, without sacrificing the visual comfort resulting from a large glass surface.
Electronic tinting, or electrochromic glass, developed by SAGE Electrochromics under the name SageGlass, is a technological solution that provides an alternative to conventional solar protection solutions such as curtains or blinds, contributing to energy savings and reducing the carbon footprint. For one thing, having large glass surfaces guarantees natural light throughout the day, particularly in workspaces, reducing the energy required for artificial lighting. For another, controlling the solar radiation that enters the premises allows the use of air conditioning and heating to be optimized, thereby contributing to greater energy efficiency for the building.
How does electrochromic glass work?
The system essentially consists of five ultrathin layers of a ceramic material which, when subjected to a certain voltage, darkens the surface due to the transfer of lithium ions and electrons from one layer to another. That is, the application of a small voltage (5V) by a power source incorporated into the window darkens the glass, allowing it to absorb and irradiate unwanted heat. When the polarity is inverted the ions and electrons return to their original position, and the glass becomes completely transparent again, maximizing the natural light and solar energy that enters the building. This solution improves the properties of low-emissivity glasses by incorporating electronic control of solar irradiation.
How is nanotechnology applied to smart windows?
SageGlass nanotechnology incorporates a series of ultrathin coating layers applied to the glass by cathodic pulverization, a manufacturing process similar to that used to manufacture low emissivity glass, so that the layers formed by transparent conductors (TC) form a sandwich around the electrochromic coating (EC), the ionic conductor (IC) and the counterelectrode (CE). Applying a positive voltage across the transparent conductors TC in contact with the counterelectrode CE causes a transfer of lithium ions through the ionic conductor IC, which are placed in the electrochromic coating EC. In turn, to compensate this charge, there is a transfer of electrons from the counterelectrode CE around the external circuit that pass through to the electrochromic coating EC.
The electronic tinting of the glass can be controlled manually with a simple switch fitted on the wall or remotely with a remote control unit. The most attractive solution, however, is to automate the system using light sensors integrated into the window frame which, depending on the incidence of external sunlight, increase or reduce the opacity of the dynamic glass to keep the thermal and illumination comfort levels inside the premises within the optimal range, contributing to saving energy in the building.
Another interesting aspect of electrochromic glass is the optimal quality of the natural light it provides, as the dynamic glass acquires the appropriate shade, according to the time of day and season of the year, to counteract excessive sunlight, eliminating unpleasant reflections in workplaces and maintaining good visual link to the outside.
Nanotechnology applied to electrochromic glass in households and workplaces provides interesting solutions in the field of domotics that contribute to saving energy in lighting and climate control, and more generally, to improving the energy efficiency of the building.
