SPD Smart Glass reduces heat gain and glare in buildings and vehicles. Partner with us today to accelerate your net-zero energy strategy.
SPD-SmartGlass panels in the roof of McEwan Hall, Edinburgh University (courtesy of Smart Glass International Ltd). Image copyright: Don Munro Photography
C.Eng CITP LEED Green Associate
Last Updated on: 4th June 2026
We started in 2009 as a manufacturer of display cases made from SPD smart glass for the art and luxury sector.
Our main objective is to reduce light exposure damage on art collections, historical items and luxury retail inventories.
We achieve this by reducing colour fading and material deterioration in paintings, silk scarves and rare manuscripts, thus protecting their market value.
Other benefits include the ability to dynamically conceal and reveal items, either for theatricality, or to provide exclusivity, or for after-hours security.
As a result, our smart glass display cases have been used to protect the following collections:
In these cases, the slight blue tint present in SPD smart glass is not noticeable, since the display case is a ‘closed environment’.
We augment the visibility of the collections with motion-triggered LEDs, featuring low-heat output and low UV content.
Furthermore, the LEDs are synchronised with the SPD smart glass using our patented smart glass operating system.
So, what has this got to do with buildings?
Well, just as a display case provides a ‘closed exhibition box’ around a small number of discrete items, the building facade itself can also be considered a ‘closed environment’.
We are not limited to museums though.
This concept is applicable to retail, hospitality, healthcare, industry and public infrastructure – basically anywhere in the built environment that needs protection from solar UV, heat and light.
Let’s look at some examples of how SPD smart glass can benefit buildings:
SPD smart glass functions as a tunable heat filter.
According to this academic study, its solar heat gain coefficient (SHGC) varies from 0.05 (when opaque) to 0.38 (when transparent).
By blocking infrared radiation, it effectively stops temperatures from rising inside the building. This, in turn, reduces the Heating, Ventilation and Air Conditioning (HVAC) demands, a major operating expense for commercial properties.
Just as with thermochromic and electrochromic smart glass, we recommend using an additional low-emittance (‘low-e’) layer on an interior surface of the insulated glazing unit (IGU).
The low-e layer reduces secondary heat gain by reflecting any energy absorbed and re-radiated by the SPD film as longer-wavelength infrared.
If the IGU incorporates a vacuum gap, warm-edge spacers, SPD smart glass and a low-e layer, the result is a robust thermal solution, capable of achieving U-values in the 0.4 to 0.7 W/m²K range.
SPD smart glass also functions as a tunable light filter, reducing glare for building occupants.
Since each smart glass panel offers individual control, a sensor-driven building management system can optimise daylighting by adjusting the facade’s tint level dynamically and per segment.
The smart glass can be activated into a clear state whenever exterior light levels are low, reducing the need for artificial lighting. The glass can be tinted when daylight levels become uncomfortable or reduce productivity.
The glass transitions from opaque (dark) to transparent (clear) in 1–3 seconds.
Compare this to electrochromic technology, which takes minutes to switch, or dyed liquid crystal glass which has a haze of 3.5% in its clear state.
The only technology with comparable switching speed, clarity and dynamic range is electrophoretic ink (‘e-ink’) smart glass but there are few manufacturers on the market at the moment.
We should bear in mind that there are cases when a slow-tinting building facade is actually beneficial, namely to avoid distracting city-centre traffic and urban wildlife.
SPD smart glass achieves a blackout effect, with visible light transmittance (VLT) close to 0% (using 90 micron thick SPD film). When a voltage activates the smart glass, it switches to crystal clarity with a VLT of 49% and a color rendering index (CRI) of 95 (see below).
This instantaneous and large dynamic range allows buildings to react to wide-changing daylight conditions.
When activated, SPD smart glass has very low haze factor (typically 2.5%) and practically no tint.
Academic tests suggest a colour rendering index (Ra) of 95, ensuring minimal distortion of interior colors, important for healthcare applications. We should point out that this data lacks independent 3rd party test house verification.
As a laminated solution, SPD smart glass offers an effective mechanical, acoustic and thermal barrier. It can be incorporated into curved glass walls, bullet-proof windows and walkable skylights, compliant with EN 356 (P4A to P6B or beyond).
There is even an option to combine smart glass with light-transmitting (translucent) concrete in order to ‘switch off’ an internal partition wall upon demand.
SPD smart glass operates at low voltages (typically 60–100 Vac) and consumes 5-10 W per square metre. This reduces cabling costs in large builds since the electrical current draw is minimal.
A step-down isolating transformer safely manages the voltage for European systems running at 230Vac. To dim the smart glass, simply chain a step-down isolating safety transformer with a variable autotransformer, which changes the voltage from 0Vac to 100Vac.
Better still, use a dedicated electronic controller, which incorporates safety and dimming functions (albeit at a higher price).
For larger installations of smart glass, engineers should consider that SPD smart glass is a reactive (electrically capacitive) load. The smart glass can thus waste energy in the electric field which activates the smart film.
This can lead to power inefficiencies and even cost penalties from the electrical utility.
More about this in our article about Power Factor and Smart Glass.
SPD smart glass patents date back to 1965, filed by inventor and licensor, Research Frontiers Inc. (RFI).
At the time of writing, RFI has 219 patents issued for this technology, which continue the early work that Dr. Edwin Land, founder of Polaroid Corporation, started in the 1930s in the area of light-control technologies.
Currently, we can find ‘SPD-SmartGlass’ technology, as it is properly termed, in automotive, aerospace, marine and architectural sectors, providing switchable shading, privacy and UV protection.
Within SPD smart glass, we find the following layers:
The glass can have a low-iron content, which reduces the green colouration typical in float glass and improves light throughput.
The rod-shaped SPD particles orient themselves randomly (following the laws of Brownian motion) when there is no electrical voltage, thus absorbing solar energy.
The percentage absorbed depends on the cell structure, the particle concentration, and the energy content of the sunlight.
Typical transmittance in this opaque state is <1% if the SPD film is 90 microns in thickness. If the SPD film is 30 microns in thickness, the transmittance in this unpowered state is close to 15%.
When the glass is activated by an AC electrical voltage, the rods align themselves in the direction of the electric field, thus transmitting light.
This gives an overall transmittance of 49% (when using 90 micron thick film) or 65% (for 30 micron thickness).
The actual numbers will vary from manufacturer to manufacturer.
SPD smart glass is a laminated structure, acting as a mechanical, acoustic and thermal barrier in architecture and transportation.
Optically, it behaves like a tunable light filter, blocking 99.9% of UV and 50% of infrared, and transitioning from opaque to transparent within 1-3 seconds.
The above spectral response of SPD film when powered (red line) shows a flat characteristic between 400 to 700 nm (visible light), proving that no extra colouration is added by the SPD film itself.
In other words, SPD smart glass has practically no tint in the activated state.
In the unpowered state (the blue line), SPD smart glass has a blueish tint, visible from the blue peak around the 420 nm mark.
The mechanism which causes the optical change is called ‘electrophoresis’, which is the diffusion of dispersed particles in a fluid under the influence of an electrical voltage.
The particles are less than 1 micron in size (i.e. one thousand times smaller than 1 millimetre). In fact, when the particles are based on polyhalides, they measure less than one-half of the wavelength of blue light, i.e. 200 nanometres, which reduces light scatter.
This is why SPD smart glass has such a low haze factor.
The fluid in which the rod-shaped SPD particles are suspended is an organic gel:- a non-aqueous, electrically-resistive liquid with a polymeric stabiliser dissolved in it. The stabiliser reduces the tendency of the particles to agglomerate, thus keeping them dispersed and in suspension.
Electrically, SPD smart glass acts like a capacitor and can be modelled similarly to a Lithium-Ion battery. This model is based on a ‘Randles’ circuit, with a Warburg Impedance modelling the diffusion mechanism.
The capacitance exhibited by the test panel of 1 square metre is 0.33 uF, with a power consumption of about 1W per square metre.
The typical operating voltage of SPD smart glass is 60-100 Vac, preferably a pure sine wave (to avoid harmonics and issues with EMC compliance testing). Many controllers on the market implement a trapezoidal waveform for simplicity.
We also recommend using metal-oxide varistors (MOVs) to protect the smart glass from mains transients and voltage surges.
These devices clamp high-voltage spikes due to lightning or heavy machinery, and ultimately increase the lifetime of your smart glass installation.
If you are looking for SPD smart glass manufacturers, distributors or installers, look no further than our parameterised search page.
Select the technology as “suspended particle devices” and press Search to reveal the suppliers.
C.Eng CITP LEED Green Associate
Manoj’s first experience with glass was in 1990 fabricating optical waveguides as a student engineer sponsored by Ferranti Semiconductors. After two decades working on hardware-software projects across telecom and automotive sectors, Manoj founded ArtRatio, a manufacturer of smart glass display cases, with clients such as the National Museum of Sweden and Harvard University. Manoj is a UK Chartered Engineer with degrees in Software & Electronics Engineering from Oxford and Southampton Universities, and holds a European patent for the sustainable display of art & luxury collections using smart glass. Through Smartglass World, Manoj now offers consultancy to ESG investors, property developers, architects, facade engineers and OEM manufacturers.
