ᐅ How can you tell the difference between energy-efficient glazing and insulated glass windows?

Hello,

Our windows are from 1996.
Are these standard double-glazed windows or do they already have thermal insulation glazing?
How can I, as a layperson, tell the difference? Or is the manufacturing year already a reliable indicator? I’m not sure when thermal insulation glazing became mandatory for new buildings.
Thank you
Jonas

... if you don’t know anything else about the building, it’s like a “guessing game” – so I would guess they are huku windows.

1. Thanks to the thermal insulation regulations introduced in 1995, thermal insulation glazing has become standard—meaning it is present in 99.5% of buildings constructed in 1996 as well.
2. As a non-expert, you can perform the lighter test. Since direct links can sometimes lead to account restrictions, try searching online for "lighter test thermal insulation glazing." This will help you identify the type of glazing installed. Alternatively, there is often a marking on the window spacers where you can find information about the glazing.

@KarstenausNRW
Thank you. I ran a test. It looks like I have insulated glass.

The lighter test is still quite reliable for the construction year...
My crystal ball suggests that in 1996, probably still 50% of the windows were installed without thermal insulation glazing.
It took a few more years and court rulings before thermal insulation glazing became widespread.