Smart Film/Glass technology, which varies light transmittance and thermal properties of windows, has been around for decades. But its overall performance has been mixed, and the technology hasn’t been fully embraced by the commercial real estate industry—until now.
“Smart windows are on the cusp of larger-scale adoption,” Amy Jiron, a technology deployment manager in the U.S. Department of Energy (DOE) Building Technologies Office, recently told Urban Land magazine.
Why the sudden rise?
Interest in automatically tinting windows is surging because buildings account for 41% of total U.S. energy consumption, according to the U.S. Energy Information Administration. Windows are often regarded as one of the least energy-efficient components those buildings, wasting 25% to 35% of a building’s energy. Not to mention the ever-growing interest in sustainability, green building certifications, and occupant wellness. It is becoming harder for commercial owners to look beyond this technology.
Although the primary benefit associated with smart glass is the reduced glare from the sun, the technology also reduces solar heat gains indoors, and both applications function to reduce a building’s electricity use and energy costs. In 2010, the National Renewable Energy Laboratory found that electrochromic windows—one of the four types of smart glass—reduced electricity consumption for cooling by up to 49%, lowered peak electrical power demand by up to 16%, and decreased lighting costs by up to 51%.
Another commercial real estate trend that could benefit from the use of smart glass technology is the focus on occupant wellness. As tenants shift to more open floor plans, natural lighting has come to the forefront, with studies showing a positive impact on employee productivity. Urban Land cites a 2012 survey of nearly 500 architects, which found that almost 98% of respondents said building occupants perform better when they have an outdoor view.
Smart glass applications have come a long way this past decade. A few years ago, smart glass companies only had the manufacturing capability to produce enough glass for one long wall—but today, that same process can accommodate enough glass for an entire building façade.
The 4 types of smart glass technology
There are generally four main smart glass technologies, explained Lori Malins of the University of San Diego’s Burnham‐Moores Center for Real Estate:
Liquid crystal Film and Glass allows light flow with privacy and changes on demand with an electric current. Since this privacy comes at the flip of a switch, no window coverings are needed, but this technology doesn’t conserve energy.
Low-E is traditionally used energy-efficient glass and is treated with an invisible metallic coating to reflect or trap heat and light. It reduces the amount of UV light that enters a space without blocking visible light. While it also reduces energy bills, prevents furniture from fading, and reduces sound levels, it’s more costly than regular glass, introduces a slight haze to windows, and has no manual control over visible light.
Thermochromic, combined with low-e technology, tints the glass based on the temperature, adapting directly to changing sunlight intensity. Given this, it manages heat and glare, and no power supply is needed. However, it can’t be manually controlled, may not receive enough heat from direct sunlight to darken, and adds weight to insulated glass units.
Electrochromic creates a chemical reaction, causing window to tint, and depending on electrical current, has selectable darkness and allows more control over sun levels. Current is not required to maintain tint level, only to change color states, and very little current is needed—an entire building takes as much current as one light bulb.
Smart glass looks into the future
Urban Land reports that the market for smart windows is poised to take off, citing three estimations for future growth. Globally, BCC Research forecasts the value of smart glass products will jump from $1.9 billion in 2014 to $3.3 billion in 2020, while fellow research firm MarketsandMarkets has an even higher estimate—$5.8 billion in 2020. And in the U.S., a Grand View Research report predicted the market will double from last year to $1.2 billion in 2021. (These numbers take into account all uses of smart glass, with Grand View Research noting architecture as the second-largest market after transportation.)
The commercial real estate industry will also benefit from vast improvements to current technology. Malins points out that the future will include increased cost efficiency, integration of smart glass with a building’s other electrical systems, photovoltaic smart glass that can generate electricity from a thin film of PV panel, wireless smart glass systems, and the inclusion of other electronics in the smart glass.
Smart Glass and Its Potential in Energy Savings
Article in Journal of Energy Resources Technology 136(1):012002 · February 2013 with 39 Reads
Impact Factor: 1.89 · DOI: 10.1115/1.4024768
1st Kaufui Vincent Wong
27.07 · University of Miami
2nd Richard Chan
Smart glass is such that its properties may be changed by application of a potential across it. The change in properties may be engineered to alter the amount of heat energy that can penetrate the glass which provides heating and cooling design options. Therein lies its potential in energy savings. Smart glass may be classified into three types: electrochromic, suspended particle, and polymer dispersed liquid crystal (PDLC). Each of these types has their own mechanisms, advantages, and disadvantages. Electrochromic smart glass is the most popular, currently it utilizes an electrochromic film with an ion storage layer and ion conductor placed between two transparent plates. The electrochromic film is usually made of tungsten oxide, owing to the electrochromic nature of transition metals. An electric potential initiates a redox reaction of the electrochromic film transitioning the color and the transparency of the smart glass. Suspended particle smart glass has needle shaped particles suspended within an organic gel placed between two electrodes. In its off state, the particles are randomly dispersed and have a low light transmittance. Once a voltage is applied, the needle particles will orient themselves to allow for light to pass through. PDLC smart glass works similarly to the suspended particle variety. However, in PDLC smart glass, the central layer is a liquid crystal placed within a polymer matrix between electrodes. Similar in behavior to the suspended particles, in the off position the liquid crystals are randomly dispersed and have low transmittance. With the application of a voltage, the liquid crystals orient themselves, thereby allowing for the transmittance of light. These different smart glasses have many different applications, but with one hindrance. The requirement of a voltage source is a major disadvantage which greatly complicates the overall installation and manufacturing processes. However, the integration of photovoltaic (PV) devices into smart glass technology has provided one solution. Photovoltaic films attached in the smart glass will provide the necessary voltage source. The photovoltaic film may even be designed to produce more voltage than needed. The use a photovoltaic smart glass system provides significant cost savings in regards to heating, cooling, lighting, and overall energy bills. Smart glass represents a technology with a great deal of potential to reduce energy demand. Action steps have been identified to propagate the popular use of smart glass.
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