How can you tell if a window is made of HR++ glass?

Read the type of glass in the glass
Look obliquely at the aluminum strip in the glass and see if you can find the product description. If you’re lucky, this will already tell you the type of glass in it. Windows from the year 2000 on usually have the product descriptions here in the glass. The aluminum strip then reads, for example: Isoglas HR++.

That’s easily found. But unfortunately, the type of glass is often not listed. What you will see is a product code. For example, see the image below. You can google those or look up/query the manufacturer, but chances are you’ll get stranded and find nothing.

Recognizing HR++ glass
Turn on your phone’s flashlight and hold it about 5 cm from the glass. If you look closely at an angle in the glass, you can see the 4 round reflections in the glass. Sometimes it seems like only 2, but it’s really 4.

If the^2nd or^3rd light of the reflection has a slightly different color you are dealing with HR++ glass. In fact, the different color of the^2nd or^3rd flame is because of a special coating applied to the inside of the glass. Contrary to what many other articles on the internet claim is that you can NOT tell with this test if it is HR, HR+ or HR++ glass. Therefore, pay close attention to 1 more thing: the window thickness must be at least 15mm. If it is less that this, then you are dealing with HR or HR+ glass.

Look at the 4 reflected lights in the photo below. It may be hard to see, but if you do this test at home and you look closely, you will really see a color difference in the lights if there is one. Do all 4 lights have the exact same color? Then it’s not HR glass.

You can see the 4 reflections circled in red on the far left in this photo (look closely…):

Tip: You can also check this with the flame of a lighter if necessary.

How do you recognize triple glass?
Triple glazing can be recognized by the fact that there are not 1 but 2 aluminum strips in the cavity of the glass.

There are 3 layers of glass here with a noble gas in between the glass layers, and 2 coatings have been applied. Often you can also read in the product description on the aluminum strips in the glass that it is HR++ or ‘triple’ glass. Triple glass cannot be recognized by using a flashlight or lighter.

Want to learn more about glass types in the home?
You can read in this blog about all the different types of glass for your home and what the exact differences are.