We conventionally use curtains to block out light and to serve as a barrier to keep heat in during winter. Curtains have also been useful for protecting our privacy. However, they haven’t always been an efficient means of conserving energy and light. Enter the smart window.
In Part 2, we talked about smart windows that use liquid crystals. The next technological innovation takes cues from earlier LCD technology and applies them to what is currently known as suspended particle devices (SPD), which are tiny light-absorbing microscopic particles that can make your windows go from dark to clear in mere seconds with the flip of a switch.
Suspended Particle Displays – To underst and how SPD windows work, think of SPDs as light valves that are placed in between two conduction-coated glass panels. The conductive coating transfers the electric current to the SPDs, which then line up to let light through, just as in LCD windows. The difference is, with an SPD window, you can adjust the level of current—usually with a remote and automatic device— and as the voltage goes down to zero, the windows darken further until they become completely dark. If you’re wondering how these windows can possibly be energy-efficient, consider this: Around 15 large SPD smart windows installed in your home will use up less electricity than a simple nightlight will.
Electrochromics – Electrochromic windows similarly work with electricity, but they work inversely to how SPDs work. They grow darker when there’s electric current and become clear in its absence. Like SPDs, they also allow varying levels of visibility. A chemical reaction (an oxidation reaction) takes place in the electrochromic material, which affects how it absorbs and reflects light. Essentially, the material changes from colored, i.e., reflecting light of some color, to transparent, or not reflecting any light at all. You can run the electrochromic windows of an entire house and spend only as much as you would to power a 75-watt bulb.
New Reflective Hydrides -This technology takes off from the same principles that work on electrochromic technology, but these employ thin films made of a nickel-magnesium alloy to switch from a transparent to a reflective state and back. These windows can switch by using either low-voltage electricity or by the injection of hydrogen and oxygen gases (gas-chromic technology). This material can potentially be even more energy efficient than st andard electrochromic windows are.
In the past, we’ve always been matter-of-fact when thinking of windows, but with recent advances in window technology, it now makes an awful lot of sense to consider our window choices in a different light. Smart window technology has matured into a full-blown consumer trend that is now making more people sit up and take notice.
