Smart window
Introduction
A smart window, also known as switchable window, refers to a type of window that can change its light transmission properties according to light, temperature, or voltage. This change is usually triggered by an external stimulus, such as sunlight or a manual switch. The technology behind smart windows is rooted in the field of materials science, specifically in the development of electrochromic materials.
History
The concept of smart windows has been around for several decades. The first patent for an electrochromic device, which is a key component of smart windows, was filed in the United States in 1973 by researchers at the National Renewable Energy Lab (NREL). However, it wasn't until the late 1980s that the first commercially viable smart windows were produced.
Working Principle
Smart windows operate based on the principles of electrochromism. Electrochromic materials can change their optical properties (transparency, reflectivity, etc.) when a voltage is applied. This change is reversible, meaning that the material can return to its original state when the voltage is removed. The most common types of electrochromic materials used in smart windows are metal oxides, such as tungsten oxide and nickel oxide.
Types of Smart Windows
There are several types of smart windows, each with its own unique properties and applications. These include:
Electrochromic Windows
Electrochromic windows are the most common type of smart window. They work by using a thin layer of electrochromic material, which changes color when a small electric current is applied. This change in color can be used to control the amount of light and heat that passes through the window.
Thermochromic Windows
Thermochromic windows change their light transmission properties in response to changes in temperature. This can be particularly useful in climates where the temperature varies significantly throughout the day.
Photochromic Windows
Photochromic windows change their light transmission properties in response to changes in light intensity. This can be useful in buildings where the amount of sunlight varies throughout the day.
Suspended Particle Devices
Suspended particle devices (SPDs) are a type of smart window that use a thin film of rod-like particles suspended in a liquid. When no voltage is applied, the particles are randomly oriented, blocking light. When a voltage is applied, the particles align, allowing light to pass through.
Applications
Smart windows have a wide range of applications, from residential and commercial buildings to transportation and even space exploration. In buildings, smart windows can significantly reduce energy consumption by controlling the amount of light and heat that enters the building. In transportation, smart windows can improve passenger comfort by reducing glare and heat. In space exploration, smart windows can protect astronauts from harmful solar radiation.
Advantages and Disadvantages
Like any technology, smart windows have both advantages and disadvantages. On the positive side, smart windows can significantly reduce energy consumption, improve comfort, and increase privacy. On the negative side, smart windows are more expensive than traditional windows, and the technology is still relatively new, meaning that there may be unforeseen issues in the future.
Future Developments
The field of smart windows is still evolving, with new technologies and applications being developed all the time. Some of the most promising areas of research include the development of new electrochromic materials, the integration of smart windows with other building systems, and the use of smart windows in new applications such as wearable technology and smart cities.