Smart Windows — Privacy meets efficiency
2 May 2021
As Debbie and I are expecting to finalize our floor plan soon, we’ve turned to looking at options for the exterior of our new home. As you can imagine, windows are incredibly important in the design of a home. They are important for the home’s aesthetics as they …
- allow exterior light to enter the home
- can be opened for ventilation
- allow solar energy to enter through southern facing windows. This can help offset home heating costs in the winter.
On the downside, older, inefficient windows can be responsible for over 25% of energy costs of heating/cooling a home. The average lifespan of a window is around 20 years. This means there are many homes that could benefit from replacement of windows.
But replacing windows isn’t cheap. According to Home Advisor, the cost of replacing windows in an average US home is between $3,000 and $10,000. The good news is that there are some unique technological options available in new windows. For these reasons and others, many homeowners are replacing windows — some opting for smart windows.
For Debbie and I, building a new home where we have input on the windows being used, there are high tech options we’re considering.
- Low-emissivity (low-E) glass has a microscopic layer of metallic particles adhered to the glass. These particles reflect infrared radiation so solar energy from the sun is reflected back, keeping a home cooler in the summer. The coating also reflects infrared radiation within a home helping to keep it warmer in the winter. In addition, the coating blocks UV rays, protecting furnishings within a home from damage from sunlight.
- Dual Action Self Cleaning Glass has a coating that keeps your windows clean. The first part of the coating uses titanium dioxide which combines with sunlight to break down organic compounds, like dirt, that sticks to glass. The second part of the coating allows water to easily rinse the broken down dirt off the windows.
Window treatments (drapes, shades, etc.) can also be expensive — you can buy them yourself or with the help of an interior designer. If you want to automate your window treatments with motorized models, the cost-per-window can be well over $1,000 depending on the fabrics you choose and the quality of the motor — higher quality motors are nearly silent. We have friends with a new home who has these and loves them. I really like the idea as Alexa can be integrated or open/close can be automated based on schedules or reacting to motion, light, etc.
An alternative to expensive window treatments are smart window films. While this might not be the best aesthetic choice for a classic Victorian home, smart window films remove the need for window treatments. Basically, the window film can be adjusted from clear to fully opaque through the application of a voltage to the film. The most common technology for smart window films is PDLC (Particle Displaced Liquid Crystal) where a voltage applied to the film causes it to be clear. When the voltage is removed — switched ”off” — the film becomes opaque. By varying the voltage — a “dimmer” — the amount of opacity can be infinitely adjusted.
The good news for consumers is that PDLC-based smart window films can be retrofit onto any window. Applying smart window film to a window is no more complicated than the application of any other window film. The tricky part is the wiring for a retrofit. Luckily with our new build we will have the opportunity to design the wiring into the electrical plan.
Obviously the electrical is the challenging part of smart glass for the average homeowner. As smart glass involves film adhered to the windows an average homeowner can do that. Smart glass is also available in multiple colors, is easy to clean and can be retrofitted to your existing glass or installed on new glass. Additionally it can be wifi enabled through your smart phone, web browser or 3rd party control interface. Most can be integrated for use with touch screen walls, controlled by remote and are automation system compatible — Crestron, Control 4, Lutron, Savant, etc.
There are three companies that sell smart window films that can be installed by a homeowner:
While it is true that the window film itself is reasonably easy to install, retrofitting wiring, through a wall, to a window location can be challenging. For those homeowners who’d prefer to engage professional help for installation, iGlass Technology has a network of installers for their window films. Similarly, Smart Tint will sell their window film to homeowners for DIY installation, but recommends installation by professionals, and works with a network of third-party installers to assist homeowners.
There are different versions of smart window film that vary by the voltage needed to control them. Window films are available that operate on standard 120 VAC house current. These can be integrated into a smart home by simply wiring them through a smart home dimmer. They can then be controlled through a voice assistant, like Amazon Alexa. If you’ve read many of my posts you know this is a particular hot button for me as I love home automation around voice commands.
The suppliers above can also provide power supplies for their low voltage films that can be integrated with a smart home hub. Smart Tint, for example, offers an RS-485 controlled power supply for their low voltage window film that can be directly controlled from a Crestron automation processor.
Buyers need to remember that these window films only become transparent when voltage is being applied to them. To keep a window transparent requires ~3 watts per square meter of film per hour. So, for every two square meters of film, it is the equivalent of powering a 450 lumen (40 Watt incandescent brightness) LED bulb.
Window films aren’t going to fit the aesthetics of every home. I’m not sure it’s a good fit for our new home but I really like the idea of automating window shading for privacy or direct sun. And Texas has a lot of sun. However, smart window film can be integrated with other window coverings to fit into almost any décor. In addition, smart window films absorb up to 98 percent of UV rays so they can protect curtain panels and other furnishings from fading due to exposure to sunlight.
Some of you may think this is going a little overboard with windows but they are an important part of any home. Now that there are high tech options for the glass to make them more energy efficient, require less maintenance and integrate them with a smart home system, it just makes sense to at least educate ourselves about it. And with smart window films priced affordably for consumers you may start seeing them installed in more of your friends’ homes.
This is one of those smart home technologies that I’m really compelled to test. I’m going to have to get my hands on a sample kit and test it. I’ll circle back on this with my results and let you know what I think. Is this something you’d consider for your home? Overkill? Or the coolest smart home tech ever? Let us know your thoughts in the comments or on social media. Until next week …
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