A lot of newer SUVs, trucks and minivans come with dark “privacy glass” on the rear windows. Many owners assume it keeps the cabin cool and hides what’s inside. It mostly does neither very well. Factory privacy glass is built to make the glass darker, and darkness alone doesn’t keep out much heat.
What factory privacy glass is
Privacy glass gets its colour during manufacturing. The maker adds colouring to the glass itself, so there’s no film on it. That colour cuts the amount of visible light coming through, which makes the windows look darker from outside.
Making glass darker doesn’t change how much infrared light gets through by much. Infrared is the part of sunlight that carries heat. So even with dark rear glass, a lot of the sun’s heat still comes into the cabin.
Darkness and heat are two different things
Two windows can look equally dark and keep out very different amounts of heat. What matters for heat is how much infrared the glass or film blocks, not how dark it looks.
Window films are built for this. 3M Ceramic IR uses ceramic particles that absorb infrared. 3M Crystalline uses more than 200 thin layers, according to 3M, to block infrared while letting visible light through. 3M lists infrared rejection of 95% for Ceramic IR and 97% for Crystalline. Factory privacy glass isn’t designed to target infrared at all.
Privacy at night
During the day, privacy glass makes it harder to see inside. At night it works the other way. When it’s dark outside and the lights are on inside the vehicle, people can see in fairly easily. If you want the back seat and cargo area to stay hidden after dark, you need darker glass than most factory privacy glass gives you.
UV protection
Factory privacy glass blocks some UV, which helps a little with fading on the seats and trim. The 3M films we install block 99% or more of UV, according to 3M’s product bulletins. That protects your skin as well as the interior.
Adding film over privacy glass
You can put window film on the inside of factory privacy glass. The film and the glass work together, so the window ends up darker than either one alone. If you only want more heat rejection and the glass is already as dark as you like, a light ceramic or Crystalline film adds heat rejection without making the window much darker.
In Alberta, this is legal on the windows where privacy glass is usually found. The rear side windows and the back glass can be any darkness, as long as the vehicle has outside mirrors on both sides. Factory-tinted glass is allowed too. The front side windows and windshield are different: no film is allowed there on a vehicle driven on public roads. Our Alberta tint law guide explains the rules.
Which film to add
- To keep out heat without going darker, choose a light shade of 3M Crystalline or Ceramic IR.
- To keep out heat and get more privacy, choose a darker shade of 3M Ceramic IR.
- To get more privacy for less money, choose 3M Colour Stable. It’s a carbon film that won’t fade to purple, but it keeps out less heat than the ceramic films.
Our “back windows” package covers the rear side windows and the back glass, which is where most vehicles have privacy glass. It costs $499 in Colour Stable, $649 in Ceramic IR and $819 in Crystalline. If you’re not sure which film suits your glass, read our guide to tint types.
To add film over your privacy glass, send us a quote request.