Interior and finishes · Glass & Glazing
Switchable Glass (PDLC and Electrochromic Glazing)
Explains how an electrically driven privacy or tinting layer differs from permanently obscured glass, and why power supply, wiring, fail state and sealed construction become part of the detailing.
Educational reference entry. Suitability depends on the complete assembly, substrate, exposure, installation method, manufacturer documentation, local requirements and qualified professional review.
Overview
What switchable glass is
Switchable glass covers two constructions. The liquid crystal type is a laminate, with droplets of liquid crystal suspended in a polymer film between the plies; the film scatters light when no supply is applied, giving a milky translucent panel, and aligns to let light pass clearly when the supply is on. The electrochromic type is instead a coating carried on one glass surface, normally assembled into a factory made insulating unit with the coating on a protected cavity face, and it changes tint as a small charge moves through it, darkening or clearing over a period rather than instantly.
The comparison people reach for is obscured or patterned glass, and the difference is the point of the product. Obscured glass is permanently textured, etched or printed, needs nothing to work and never changes. Switchable glass achieves the same privacy on demand, but only because an electrical supply, a controller and a cable route have been designed into the frame, the reveal and the electrical installation of the building.
That electrical dependency shapes everything else. Wiring leaves the pane at the edge, so the frame has to receive it and conceal it. A controller and a supply need a location, an isolator and access for maintenance. The state the panel takes when the power is off is a characteristic of the product to be confirmed rather than assumed. And because the active layer is sealed inside a factory made pane or unit, a fault means replacing that pane or unit rather than repairing the layer.
Terminology
Common names and aliases
These names describe the same thing. The library keeps one entry per material so that an acronym, a trade name or a regional spelling never becomes a second, thinner page.
- switchable smart glass
- pdlc glass
- electrochromic glazing
Applications
Common applications
Where this material is typically encountered. A typical application is not a statement that it suits your project.
- Internal partitions and meeting room screens where privacy is wanted only some of the time.
- Bathroom and ensuite screens within a bedroom, where openness and privacy are both wanted.
- Doors and vision panels in interiors where the glazing changes role through the day.
- External glazing where tinting on demand is being used to manage glare and solar gain.
- Rooflights and roof glazing where shading hardware would be awkward to install or maintain.
Consideration
Where it is commonly considered
- Where privacy is needed intermittently and a permanent obscured finish would spoil the room the rest of the time.
- Where blinds or curtains are impractical, hard to reach or unwanted for cleaning and appearance reasons.
- Where the electrical design is still open and cable routes to each pane can be planned properly.
- Where the client has seen a working sample and understands how the switched and unswitched states actually look.
Professional review
Where additional professional review is especially important
These are the situations where the answer depends on the specific building, and where a qualified professional should be involved before anything is decided.
- Where a supply cannot be routed to the pane without disturbing finishes that have already been decided.
- Where the panel must be relied upon for privacy at all times, since the behaviour without power is a product characteristic to confirm.
- Where a full blackout is expected, because the liquid crystal type still transmits light in its obscured state.
- In any position where impact is foreseeable, which is a matter for the local requirements and a qualified professional.
- In fire resisting construction, where the complete tested assembly and the relevant authority govern what may be installed.
Properties
Key properties to discuss
Qualitative topics worth raising. Measured values, classes and grades come from the manufacturer's technical documentation for the specific product, not from a reference page.
- Appearance
- The obscured state of the liquid crystal type is a milky translucent white rather than a neutral frosting, and the clear state can carry a faint haze. Electrochromic panels shift tint gradually and may not tint evenly across a large pane at first.
- Installation dependency
- Cable exits at the edge of the pane, so the frame, the reveal and the controller position are designed together with the electrical installation. This is coordination work rather than a glazing detail added at the end.
- Documentation
- The manufacturer's information covers the supply required, the controller, the behaviour without power, the switching characteristics and the warranty, and it is specific enough that general expectations about smart glass are unreliable.
- Repairability
- The active layer is sealed inside the finished pane or unit, whether as an interlayer or as a coating, so a failure of the film, the coating or the connection means replacing it rather than servicing it. Access for that replacement is worth thinking about before the panel goes in.
- Thermal behaviour
- The electrochromic type is used partly to manage solar gain, but the effect belongs to the specific product and the whole unit, and the manufacturer's own information is the only sound basis for a design decision.
- Maintenance
- Controllers, isolators and connections need to remain accessible after handover, and someone has to know they exist, which is a handover documentation point as much as a technical one.
Exposure
Exposure and environmental conditions
- Is this panel internal or external, and does the product literature address that exposure?
- Will the pane be subject to condensation, splashing or wash down in normal use?
- How much direct sun does the glazing receive, and does the manufacturer comment on that?
- Is the switching expected to happen often, and by whom in daily use?
- Is the panel in a room where a power interruption would matter to the occupants?
Assembly
Substrate and system dependencies
What this material sits on, is fixed to or depends on. This is usually where performance is won or lost.
- The frame or partition system has to receive the cable exit and conceal it without pinching the connection.
- An electrical supply, isolator and controller position are part of the design, agreed with the electrical designer.
- Where the panel sits in a door, the cable route through a moving leaf is a detail that needs solving specifically.
- Where the glass forms part of a sealed unit, the laminated switchable ply is combined with the unit by the processor.
Appearance
Appearance and finish considerations
- The obscured state is translucent rather than opaque, so shapes and light are still read through the panel.
- Edge detail can reveal the cable exit, and covering it neatly is a frame design question raised early.
- Colour and haze in the clear state vary between products, so samples are compared side by side in the actual light.
- Large panes may show variation across the area when switching, which the manufacturer describes for its own product.
Durability
Durability questions
Questions to raise rather than a service life to expect. No material has a universal lifespan — it depends on the assembly, the exposure and the upkeep.
- What does the manufacturer's warranty cover for the film, the connection and the controller separately?
- How many switching operations does the product literature describe, and how does that compare with expected use?
- How will the pane be protected during construction, given that damage to the edge affects the connection?
- Who is responsible for the interface between the glazing supplier and the electrical contractor?
- What happens if the controller becomes unavailable later in the building's life?
Upkeep
Maintenance and repair considerations
- Who holds the manufacturer's documentation after handover, and does the occupier know where it is?
- How is the controller reached for service without dismantling finished work?
- What cleaning products does the manufacturer accept at the glass and at the edge seal?
- How is a failed pane replaced, and what does that involve in this location?
Installation
Installation dependencies
What the installation depends on — not how to do it. Method belongs to the manufacturer's instructions and the trades carrying out the work.
- Electrical first fix has to anticipate the pane, so the cable route is designed before the partition is built.
- Panes are made to size with the connection in a set position, and neither can be altered on site.
- The glazing installer and the electrical contractor coordinate the connection, testing and commissioning between them.
- Handling protects the cable exit at the edge, which is the most easily damaged part of the panel.
- Commissioning and a demonstration to the occupier are part of the work rather than an afterthought.
Documentation
Documentation to request
Ask for these in writing, for the specific product being proposed, and keep them with the project record.
- The manufacturer's product literature covering the supply, the controller and the switching behaviour.
- A written statement of what the panel does when the supply is interrupted.
- Wiring and connection details for the glazing supplier and the electrical contractor to work from.
- Warranty terms for the glass, the film, the connection and the controller.
- Cleaning and maintenance guidance for the finished installation.
Conversations
Questions for qualified professionals
Bring these to the relevant qualified professional, manufacturer or authority. Requirements vary by project and location.
- What is this glazing being asked to do, and is switchable glass the simplest way to do it?
- Where does the supply come from, and who is designing the cable route to each pane?
- What does the panel do when the power is off, and is that acceptable for this room?
- Has the client seen a working sample in both states and in daylight?
- Who coordinates the glazing supplier and the electrical contractor on site?
- Where do the controller and isolator sit, and how are they reached afterwards?
- What is the replacement route if a pane fails once the building is occupied?
Blind spots
Commonly overlooked points
- The obscured state is translucent, not opaque, and a client expecting a blackout will be disappointed.
- Cable routes must be settled before partitions are built, and retrofitting one into finished work is disruptive.
- The unpowered state is a product characteristic, and assuming it will fail obscured is exactly the kind of guess that causes trouble.
- Controllers and isolators disappear behind finishes if their positions are not agreed and recorded.
- Switching may be slower and less uniform than a showroom demonstration suggests, particularly on a large pane.
What this page does not do
- Electrical work belongs to a qualified electrician working with the glazing supplier, and nothing on this page is an instruction for carrying it out.
- Where a pane sits somewhere that may call for a particular glass type, that is determined by the local requirements and by a qualified professional for the specific opening.
- No performance figure is given here; the manufacturer's documentation for the specific product is the only sound basis for a design decision.
Related entries
Related materials
Materials from the same family, an adjacent role in the assembly, or a shared application.
Inspiration
Related Ideas Library pages
Design directions where this material commonly appears.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this material comes up.
Go deeper
Related Build Design Hub guides
Planning guidance and neutral comparisons behind the decisions on this page.
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