Switchable Smart Glass — PDLC and Electrochromic

What it is

Glass laminated with an electrically switchable film. Two distinct technologies sit under the label, and they do different jobs.

	PDLC	Electrochromic
Switches	Clear ↔ opaque	Clear ↔ tinted
Speed	Near instant	Minutes
Purpose	Privacy	Solar and glare control
Typical use	Interior partitions	Exterior facade glazing
Opacity	Fully obscuring	Never fully opaque

What the specification must cover

Because this is glass and an electrical installation, both sides need defining:

• Panel sizes and the maximum size the film is available in
• Power supply location and the concealed cable route to each panel
• Switching method — wall switch, BMS, occupancy sensor, app
• Failure state: what the glass does when power is lost
• Edge detail, since the busbar and wiring must be concealed within the frame
• Safety classification of the laminated build-up to IS 2553 (Part 1)

The wiring is the part that gets missed. A switchable panel needs a cable to it, and that route has to be designed into the partition head or the floor before anything is built.

Where projects go wrong

• Specified late, after partitions are designed with no cable route.
• Power failure state not considered, so a boardroom goes opaque in an outage, or a facade sticks clear during peak sun.
• Expecting solar control from PDLC. It does not deliver it.
• Panel size exceeding film width, forcing a joint the architect did not expect.
• No isolation or maintenance access to the driver and transformer.

Standards referenced

Architectural safety glass to IS 2553 (Part 1). Fenestration provisions under ECBC 2017. Electrical installation practice under IS 732.