Smart Film Power Consumption —
Running Costs Explained
How much electricity does smart film actually use? This guide covers power requirements per square metre, annual running costs by installation size, transformer sizing, and how BMS integration reduces energy waste.
3.7W
Per m² when clear
0W
Per m² when opaque
~£41
Est. annual cost (20m², office)
AC60V
Operating voltage
How Smart Film Consumes Power
Smart film uses electricity only when switched to the clear (transparent) state. In its default unpowered state — opaque — the film draws zero current. This is a fundamental characteristic of PDLC technology: electrical energy is required to align the liquid crystal droplets into the transparent configuration. Remove the power and the crystals return to random orientation (opaque) without any energy input.
This means that for environments where privacy (opaque) is the most common state — healthcare consultation rooms, SEND classrooms, private meeting rooms — smart film is predominantly using zero power. Electricity is only drawn during the periods when the room is being used in its transparent, open configuration.
For environments where transparent is the default state — office corridors, open-plan areas — the film draws its rated power continuously while occupied. This is where BMS and occupancy sensor integration delivers meaningful energy savings by switching zones to opaque when rooms are unoccupied.
For full technical specification including electrical requirements, see the specification guide.
Smart Film Annual Running Cost Examples
Based on 3.7W/m² consumption rate and UK commercial electricity rate of £0.28/kWh. Actual costs will vary.
Single Meeting Room (15m²)
Medium Office Floor (60m²)
NHS Ward Partition (30m²)
Residential Bathroom (4m²)
Calculations assume film is powered (clear) for the full period shown. BMS integration and occupancy control will reduce actual consumption significantly.
Transformer Sizing for Smart Film
Every smart film installation requires a low-voltage AC transformer. The transformer steps down from 240V mains to AC60V — the operating voltage of PriviFilm™ PDLC film. Transformer sizing is critical: an undersized unit causes uneven switching, reduced clarity, and early component failure.
Sizing rule: calculate total film area (m²) × 3.7W/m² = total connected load in watts. The transformer should be rated to at least 120% of this load. Example: 20m² × 3.7W = 74W → minimum transformer: 89VA (round up to 100VA or 150VA unit).
Multiple zones can share a transformer provided the total connected load does not exceed the transformer's rated output. Where zones require independent switching — separate meeting rooms, for example — a dedicated transformer per zone (or per floor) is standard practice.
Never undersize the transformer
An undersized transformer is the most common cause of poor switching performance. Always calculate at 120% of connected load and round up to the next standard rating.
When Smart Film May Not Be The Right Solution
Smart film is the correct specification for most privacy glazing applications — but there are scenarios where alternative solutions should be considered.
Blackout required
Smart film does not black out — it produces a bright white opacity when unpowered. If complete light exclusion is required (cinema rooms, photography studios, sleep environments), smart film should be combined with blackout curtains or blinds.
Variable tinting needed (not full privacy)
PDLC film switches between clear and opaque — it does not offer variable tint levels. If the requirement is light control without full privacy (atrium roofs, skylights, sunrooms), SPD (Suspended Particle Device) or electrochromic tinting may be more appropriate.
Curved or textured glass
Smart film is a flat substrate and cannot conform to curved, bent, or textured glass surfaces. For curved glazing, factory-laminated smart glass or alternative privacy solutions are required.
No electrical supply practical
Smart film requires a permanent low-voltage electrical connection. In listed buildings, conservation areas, or heritage properties where running new electrical circuits is prohibited or impractical, static privacy solutions (frosted film, manifestations) may be the only viable option.
Budget-constrained projects
Smart film has a higher upfront cost than static alternatives (frosted film, blinds, curtains). For projects where capital cost is the primary driver and switchable functionality is not required, static solutions provide privacy at lower initial expense.
Exterior glazing
Smart film is designed for interior application. Exterior exposure to weather, UV degradation, and temperature extremes reduces service life. For exterior switchable glazing, factory-laminated smart glass units are required.
Smart Film Energy Questions
How much power does smart film use per square metre?
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PriviFilm™ draws approximately 3.7 watts per square metre when powered (clear state). In the unpowered (opaque) state, power consumption is zero. This is based on manufacturer testing at AC60V operating voltage.
How much does it cost to run smart film per year?
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For a typical 20m² office installation powered for 8 hours per day, 5 days a week: 20m² × 3.7W = 74W; 74W × 8h × 250 days = 148kWh/year. At £0.28/kWh, annual running cost is approximately £41. This is less than many office desk lamps. This is less than many office desk lamps.
Does smart film use power when opaque (switched off)?
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No. Smart film in its default opaque state requires zero power. Power is only consumed when the film is actively switched to the clear/transparent state. If your smart film defaults to opaque, it only uses energy when transparency is needed.
Can smart film be connected to a building management system to reduce energy waste?
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Yes. BMS integration allows smart film zones to be tied to occupancy data, room booking systems, and energy management dashboards. Zones automatically switch to opaque (zero power) when rooms are unoccupied, eliminating unnecessary energy draw.
What size transformer is needed?
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The transformer must be sized to at least 120% of the total connected film area in watts. For 20m² of film at 3.7W/m² = 74W total; the transformer should be rated at minimum 89VA. Most installations use transformers in the range of 100VA–500VA depending on zone size.
Is smart film energy efficient compared to electric blinds?
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Smart film has comparable or lower power draw than motorised electric blind systems when both are in active use. The key difference is that smart film is the entire partition — it eliminates the need for both the glass partition and the blind, reducing embodied carbon and ongoing maintenance energy.
Questions About Smart Film for Your Project?
Our technical team can advise on electrical requirements, transformer sizing, and BMS integration for your specific installation.
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