What is Electrochromic Smart Glass?
Essentially, Electrochromic smart glass (ESG) is high tech glass that can change its properties according to the salient needs of its environment. The glass can be clear, opaque, tinted or colored, has the capability to modulate heat and light transmission and can be used in a variety of applications.
ESG is one of several emerging products that fall under the category “electrically-tintable” devices whose optical properties vary when an electric field or current is applied across the device. For the ESG, the absorptance or the reflectance of the active layers change, thereby modulating the amount of light (electromagnetic radiation) that passes through the coated substrates or glass. For suspended particle and polymer-dispersed liquid crystal devices the transmittance is modulated by e-field induced shifts in physical orientation of the active components.
The use of ESG in architectural applications is of interest globally and to Applied Materials for many reasons, especially as part of our commitment to clean technology and energy conservation.
In the U.S., the energy consumed by all buildings (commercial and residential) is estimated to be about 40% (35 Quads, 1 Quad = 1E15 BTU) of the nations total annual energy consumption. Heat transmission through windows (heat gain in summer and heat loss in winter) accounts for about 20% of the total energy consumed by buildings. Thus, the current governmental and industrial efforts in Net-Zero-Buildings (NZB) require improved window technologies.
If ESG were used in all building windows and if the ESG tint were optimally synchronized with the amount of artificial interior lighting, then the potential savings could be as much as 33% of the window’s related consumption vs. the current installed base of predominantly non-low-e glasses.
Another reason is general comfort and productivity. Unlike the static low-e coated windows, ESGs are dynamic devices where the state of transparency can be controlled by the user for maximum comfort and productivity. Dynamic control of exterior light and the energy savings bring added benefits in reduced balance of the systems requirements, such as the interior and/or exterior blinds and smaller HVAC systems, leading to increased conservation of materials and a reduced overall carbon footprint.
There are already a few ESG products in various markets. One mature device (and market) is the variable reflectance, rear-view mirrors with sensor based automation. They reduce the glare from headlights at night. The emerging ESG products include sunroofs for high end vehicles, airplane (Boeing 787) and yacht windows, and architectural windows (skylights).
ESG represents an opportunity to apply Applied Materials’ expertise in thin film deposition and manufacturing technologies to bring significant improvements to the current cost-performance value proposition and end product performance portfolio. With the recent U.S. federal research grant from the Department of Energy, Applied is continuing to progress toward its vision for ESG.