Understanding the Mechanism of Smart Windows

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Home Improvement

Suspended Particle Devices

Windows play a crucial role in houses and commercial buildings. They not only provide light, but also generate heat. However, they are not typically considered as a technological innovation. Nevertheless, Research Frontiers has developed a revolutionary technology that can enable a window to transform from clear to opaque and vice versa instantly.

Traditionally, curtains and mini-blinds have been used to block light and provide privacy, but they do not block all the light. Research Frontiers has employed an innovative approach that utilizes suspended particle devices (SPD) to create a window that can switch from clear to dark in a matter of seconds. Here are the components of SPD light-control windows:

  • Two panels of glass or plastic
  • Conductive material – used to coat the panes of glass
  • Suspended particle devices – millions of these black particles are placed between the two panes of glass
  • Liquid suspension or film – allows the particles to float freely between the glass
  • Control device – automatic or manual

The working mechanism of SPD windows is simple. Millions of SPDs are placed between two panels of glass or plastic, which is coated with a transparent conductive material. When electricity comes into contact with the SPDs through the conductive coating, they align in a straight line and allow light to pass through. Once the electricity is removed, they return to a random pattern and block light. Decreasing the voltage darkens the window until it becomes entirely dark after all electricity is removed.

Users can apply a moderate amount of voltage to the conductive material on the window panes through a control device. Several control methods are available with the SPD light-control windows, including remote and automatic devices. The windows can be controlled manually with a rheostat or remote. Alternatively, photocells and other sensing devices can be used to control the level of light automatically.

Research Frontiers has about 470 worldwide patents on this light-control technology and has several licensees, including Polaroid and GE. Suspended particle devices can be used for various other consumer products, including sunroofs, sun visors, rearview mirrors, ski goggles, and flat-panel displays for computers.

If you are wondering how to get smart windows without replacing all the windows in your home, Research Frontiers has a patent – No. 6,429,961 entitled “Methods for Retrofitting Windows with Switchable and Non-Switchable Window Enhancements” – which will allow homeowners to upgrade their existing windows with SPD technology. Additionally, powering 15 large SPD smart windows in your home consumes less electricity than running a simple night-light.

Liquid crystals and electrochromics are two other types of smart-window technology besides SPD. While SPD uses suspended particles, electrochromics performs the same functions and liquid crystals have been in use for many years. The original discovery of light-absorbing crystals can be traced back over 100 years ago, when an English chemist noticed green crystals forming in a tray of iodine after his dog accidentally urinated on it. These crystals were later found to have the ability to filter out light, and were used by inventor Edwin Land to create a pair of glasses that could block out light.


1. What are smart windows?

Smart windows are windows that can change their tint or transparency level according to the amount of light or heat they receive. They use advanced technology to regulate the amount of light and heat that passes through them, helping to reduce energy consumption and improve comfort levels for occupants.

2. How do smart windows work?

Smart windows use either electrochromic, photochromic, or thermochromic technology to change their tint or transparency level. Electrochromic smart windows use an electric charge to change the color of a thin layer of material, while photochromic smart windows use light to trigger a chemical reaction that darkens the glass. Thermochromic smart windows use heat to change the tint of the glass.

3. What are the benefits of using smart windows?

Smart windows offer several benefits, including improved energy efficiency, reduced glare, increased privacy, and improved comfort levels for occupants. They can also help to reduce the need for artificial lighting and air conditioning, which can lower energy costs and improve the overall sustainability of a building.

4. Can smart windows be controlled manually?

Yes, smart windows can be controlled manually using a remote control or a wall switch. This allows occupants to adjust the tint or transparency level of the windows to their desired level, providing greater control over the amount of light and heat that enters a room.

5. Are smart windows expensive?

Smart windows can be more expensive than traditional windows, but their energy-saving benefits can help to offset the initial cost over time. Additionally, the cost of smart windows has decreased in recent years as the technology has become more widely available.

6. How long do smart windows last?

Smart windows can last for many years if they are properly maintained. The lifespan of a smart window will depend on the type of technology used, the quality of the materials, and how well it is installed and maintained.

7. Can smart windows be retrofitted to existing buildings?

Yes, smart windows can be retrofitted to existing buildings, but the installation process can be more complex and expensive than installing them in a new building. It is important to work with a qualified professional to ensure that the installation is done correctly.

8. Do smart windows require any special maintenance?

Smart windows do not require any special maintenance beyond regular cleaning. However, it is important to follow the manufacturer’s instructions for cleaning and care to ensure that the technology continues to function properly.

9. What is the difference between smart windows and regular windows?

The main difference between smart windows and regular windows is that smart windows can change their tint or transparency level to regulate the amount of light and heat that enters a room. This helps to improve energy efficiency and occupant comfort, while regular windows do not offer this level of control.

10. Can smart windows be used in all types of buildings?

Yes, smart windows can be used in all types of buildings, including residential homes, commercial buildings, and public spaces. They are particularly useful in buildings that receive a lot of sunlight or have high energy consumption.

11. Are there any downsides to using smart windows?

One potential downside of using smart windows is that they can be more expensive than traditional windows. Additionally, the technology may not be suitable for all buildings or climates, and the installation process can be more complex than installing regular windows.

12. What is the future of smart windows?

The future of smart windows looks promising, as advances in technology are making them more efficient and cost-effective. Smart windows are also being integrated with other building systems, such as lighting and HVAC, to create a more seamless and sustainable building environment.

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