Smart glass technologies include electrochromic, photochromic, suspended particle, and liquid crystal device technologies (PDLC)
While the basic concept behind all smart windows is the same, they can be made in several different ways, each with a different method and properties for blocking light. Critical aspects of smart glass include material costs, installation costs, electricity costs and durability, as well as functional features such as the speed of control, possibilities for dimming, and the degree of transparency.
Why Use Smart Glass?
- Control the amount of privacy, light and heat that enters a space manually or automatically.
- Switch instantly or dim anywhere in between
- No need for blinds or curtains
- Enable privacy while retaining natural light
- 98% UV protevtion
Smart Glass Application
Corporate office building / Residential / Healthcare facilities / Retail / Transportation
Passive Smart Glass : Responds to non-electrical stimuli(heat, UV)
Cannot be manually controlled
Active Smart Glass : Responds to an electrical stimulus and is controllable manually or automatically
Electrochromic, Suspended particle device(SPD),
Polymer dispersed liquid crystal(PDLC)
Electrochromic
- Typically used for solar control on exterior glass
- The visible light transmission in the darkest state can be less than 3%. The resulting shading has limited privacy function as it can still be seen through.
- Consists of two glass panes with several layers sandwiched in between.
- It works by passing low-voltage electrical charge across a microscopically thin, clear conductive coating on the glass surface, which activates electrochromic layers that change color from clear to dark.
- The electric current can be activated manually or by sensors which react to light intensity.
- One advantage of the electrochomic smart window is that it only requires electricity to change its opacity, but not to maintain a particular shade.
- The switching speed of electrochomic glass is very slow and varies depending upon the size of the panel ( larger panels typically take many minutes to switch.) The consistency of tint change that begin at the glazing's outer edges and then move inward (known as the 'iris effect')
Suspended particle device (SPD)
- In suspended particle devices (SPDs), a thin film laminate of rod-like nano-scale particles is suspended in a liquid and placed between two pieces of glass or plastic, or attached to one layer.
- When no voltage is applied, the suspended particles are randomly organized, thus blocking and absorbing light.
- When voltage is applied, the suspended particles align and let pass.
- Varying the voltage of the film varies the orientation of suspended particles, thereby regulating the tint of the glazing and amount of light transmitted.
- The visible light transmission at the darkest state of SPD glazing is around 0.5% and the process takes one to three seconds after power is applied, regadless of the size of the window.
- The resulting dark blue shading blocks light and provides only partial privacy.
Polymer dispersed liquid crystal(PDLC)
- Polymer dispersed liquid crystal is simply micro droplets of liquid crystal encapsulated in a polymer matrix.
- The liquid crystal respond to an electrical charge. In a static state, the liquid crystal molecules remain in a randomized configuration that refracts the light that enters the mixture, making it appear opaque.
- When electricity is applied, the molecules line up the direction of the electric field, allowing light to pass through what is now essentially a transparent surface.
- When electrical change is deactivated, liquid crystal droplets again become randomly oriented, the incoming light is again heavily scattered and does not pass through in a straightforward manner, resulting in fully blocked images
- Liquid crystal applications are a familiar technology for numeric and flat panel displays.
- Liquid crystal display, or LCD, is the most popular flat panel display technology, seen in portable computers, cell phones, calculators, digital clocks, gas pumps, and watches, etc.
- In LCD, applied electricity change the shape of liquid crystals to allow light to pass through individual elements, thus forming images, figures, and numbers on the displays.
PDLC Technology
- Can be used for interior or exterior glass applications.
- Switches from opaque (milky white or gray) to clear in less than a second.
- Can run on standard 110-volt AC.
- Available in a self-adhesive switchable film that can be applied to existing window.
- Provides total privacy in its opaque state (cannot be seen through)
Electrochromic Technology
- Used for exterior glass applications, for solar control
- Not used for interior privacy.
- Long transition time from clear to opaque. Larger windows can take five to 20 minutes.
- New glass must be installed. no film option for existing glass.
- Not used for privacy as you can still see through it in its dark (tinted) state.
Privacy, Occupant Comfort, Energy Use Reduction with PDLC Technology
- Blocks 99% of UV rays which cause damage and discoloration of interior walls, carpets, and furnishings.
- In its opaque state, PDLC smart glass can reduce solar heat gain by up to 40%
- The reduced heat gain in hot months helps keep the interior cooler, thus requiring less air conditioning producing increased occupant comfort, and providing cost savings.
