The Future is Now
There is a lot of talk about dynamic glass these days, but there are still many misperceptions about what it exactly is. Dynamic glass is glass that changes visible light transmission and solar heat gain properties with the application of voltage, light or heat. There are four different ways to achieve this: Liquid Crystal Display/ Polymer Dispersed Liquid Crystal/Suspended Particle Display for privacy glass; electrochromic glass; thermotropic glass; and thermochromic glass.
The most widely known application for dynamic glass is in the privacy glass product category, which consists of either LCD, PDLC or SPD. This family of products offers instant on/off capability at the flip of a switch. Great for privacy as it completely obscures vision, it is primarily used in interior applications. On the residential side, privacy glass has applications in very high-end residential projects, where it is mostly used in bathrooms.
Although the technology obscures vision, it does not reduce visible light transmission. Instead, it provides the same amount of light in a diffused manner. This product is often confused and thought of as electrochromic because it uses electricity, but it is not.
|Shown is Suntuitive Glass by Pleotint—a thermochromic type of glass—in action. This type of dynamic glass responds intelligently to direct sunlight, absorbing the light and tinting to shade the home. It also reflects the heat it absorbs to the outside of the home. (Images courtesy of Pleotint LLC.)|
Electrochromic glass uses a low voltage current to shift ions in a microscopic coating that causes it to absorb light (or tint). The only commercially successful electrochromic glass application is for rearview mirrors, a technology that was pioneered by Dr. Harlan Byker 35 years ago. Today, more than 30 percent of all vehicles utilize these mirrors to reduce glare.
Today, you also see electrochromic glass in commercial buildings. The glass has four to five stages (tints) and offers many variables. These products are fantastic at reducing glare and blocking solar heat before it enters the building, providing potential energy savings. The greatest advantage for electrochromic glass, though, is that it offers an increased level of comfort for the occupants of the building.
Electrochromic glass in residential applications works best if the windows are not operable, a fact that substantially narrows the number of applications for it. Operable windows can be done, but the integration is not easy and the solutions for operable windows—such as bridging the wires to bring power and communications—are not very reliable or elegant.
There are also still some overall challenges in this category, mostly with complex control systems and installation procedures. Because the insulating glass units all require power, it can be challenging to plan the integration.
Thermotropic glass is another type of dynamic glass where the product reacts to heat, mostly from ambient temperature. This type of product has a threshold temperature and, once achieved, the glass will change and provide the necessary benefits. The glass has two states, on or off, and looks great in either one. But, the transition during the tint change looks a little different and some people find it hard to accept.
This product is a relatively affordable option and should see more traction in the future. Especially considering that thermotropic glass doesn’t need wires, it should integrate into the residential sector easily. However, the main producer of this technology is restricted by some size limitations that would exclude it from doors, picture windows and windows with shapes. Cold climates might offer some difficulties with this product as well, but operable windows and doors should integrate with ease.
As the sun heats the glass, thermochromic technology responds intelligently to direct sunlight on the surface of the glass, absorbing light and tints. The heat is reflected to the outside with low-emissivity glass. In plain terms: it uses the heat from the sun to block the heat from the sun. This option is infinitely variable and, because ambient temperatures have little to no effect, it works well in all climate zones.
The technology—which is not a coating, but incorporates inorganic ions in the polyvinyl butyral interlayer of the glass—can be incorporated into different kinds of glass, and has been successfully installed in residential windows of all types. This glass is the least expensive of all the dynamic glass options, and it can be universally used in any material of window, as well as in any shape and style, and in glass options such as double pane or triple pane, argon, etc.
A Dynamic Future
The structures we build live in a very dynamic and ever changing world. The demands placed on them to perform and be efficient are harder every day. Static glass just does not address these challenges in the same way that a dynamic glass product can.