10 Nov

What are self-cleaning windows, and do they really work?

If you’re looking at buying new windows in the near future, you’ve probably discovered ‘Self-cleaning glass’. You may have even considered the brilliance of never – ever – needing to clean your windows again! After all, self-cleaning means never needing to pull out the squeegee from under the kitchen sink , right?

To let you down gently, self-cleaning windows do not exist.

We know what you’re thinking – but you’ve read about them extensively, your neighbours have self-cleaning glass, you may have even received a quotation from another brand, highlighting the many fantastic properties of self-cleaning glass!

But it’s important to clarify that this doesn’t mean that you will never need to clean your windows… In fact, there is a slightly different way to care for this glass to maintain the desired benefits.

What are self-cleaning windows?

The difference between standard windows and any that are referred to as ‘self-cleaning’ is the latter have an ultra-thin outer coating of titanium dioxide. The same compound that is responsible for providing paint with a nice sheen, or even in some cosmetics to brighten the appearance of skin.

This coating can’t clean your glass, you’ll still need to follow our guide to cleaning windows. Instead, it creates a lower maintenance finish than uncoated glass.

How does ‘self-cleaning glass’ work?

The titanium dioxide finish works in two ways; First by light-activation (known as photocatalytic), and second with water (hydrophilic).

The photocatalytic properties of this compound create a chemical reaction when it is met with the sun’s UV rays. The Ultraviolet of the sun generates electrons on the glass. These turn water molecules in the air into what is known as ‘hydroxyl radicals’, or in layman’s terms, dirt-attacking agents that can break up organic surface debris into smaller pieces. The surface then relies on a rinse of water, either from rainfall or from your bi-annual clean.

Glass is naturally considered ‘hydrophobic’, which means that any water dropped onto the glass will bead rather than spread over the surface. Over time this will lead to dirty streaks running down each pane. So the hydrophilic properties of titanium dioxide encourage water to do the opposite. Instead of beading, any water will spread out across the glass and help to rinse away any dust, dirt and debris that may have fallen on the glass.

What are the benefits?

The greatest benefit to ‘self-cleaning glass’ is that its low maintenance. The titanium dioxide coating means that you won’t need to clean your glass as often. But when you do, thanks to the photocatalytic properties, dirt will easily wipe away.

The coating works best on areas that are hard to reach for cleaning, such as upstairs windows or a roof lantern, as it will help to keep your glass looking cleaner for longer. So there’s less need to be scaling a ladder with a bucket and squeegee, or reducing the need to hire a window cleaner.

What are the disadvantages?

Firstly, they tend to be more expensive. That’s down to the cost of the coating and the extra time to apply it over the glass. The next disadvantage is that the ‘cleaning’ process relies on UV light and rain to work, so it can be a very slow and continuous process. It also will vary depending on your location and the weather you experience. But overall, the results won’t be the same as a visit from your window cleaner.

Finally, although the coating is designed to last a long time, it’s important to remember that throughout its lifetime (and cleaning) the glass will need to be recoated to maintain the same low-maintenance benefits.