Yes, glass does protect from UV rays to some extent. Standard window glass blocks most UVB rays (which cause sunburn), but it still allows a significant amount of UVA rays to pass through. This means that, while you’re less likely to burn indoors, prolonged sunlight through windows can still contribute to skin ageing and fading furniture.
Many homeowners assume that sitting indoors protects them completely from the sun’s harmful ultraviolet (UV) rays. While glass does provide some protection, it doesn’t block all UV radiation.
Understanding how UV rays interact with window glass can help you protect your skin, furniture and flooring, especially if your home has large windows, conservatories or south-facing rooms.
In this guide, we explain how much UV glass blocks, whether double glazing helps, and what types of windows provide the best protection.
Glass protects against UV rays to some extent. However, not all glass is created equal. Standard window glass blocks almost all UVB rays (97% to be precise), which are the rays primarily responsible for sunburn, but allows a significant amount of UVA radiation in.
UVA rays penetrate deeper into the skin and are linked with the following:
This means that even though you may not get sunburn indoors, prolonged exposure to sunlight through windows can still have harmful effects on both you and your belongings over time.
To understand why some UV rays pass through glass, it helps to understand the two main types of ultraviolet radiation produced by the sun.
UVA rays have the longest wavelength and can pass through most standard window glass.
These rays are present throughout the day and can:
UVB rays, on the other hand, are shorter wavelength rays that cause sunburn.
The good news is that standard window glass blocks nearly all UVB radiation, which is why you’re unlikely to get sunburn while sitting indoors.
The amount of UV protection depends on the type of glass installed in your windows.
Here’s a general guide to how different glazing options perform.
| Type of glass | UV protection |
| Standard glass | Blocks most UVB but allows significant UVA through |
| Double glazing | Provides improved UV protection |
| Laminated glass | Can block up to 99% of UV radiation |
| Low-E coated glass | Blocks a large percentage of UV rays |
Modern glazing technology has significantly improved UV protection compared to older single-pane windows. This means that upgrading your windows can help protect both your home and your health.
In the UK, industry standards are in place to ensure a certain level of UV protection for windows. The British Standards Institution (BSI) has established guidelines for window manufacturers to meet specific UV transmittance requirements. The current standard, BS EN 410:2011, sets limits on the percentage of UV radiation that can pass through a window. Windows that meet these standards provide a level of protection against UV rays, minimising the damage caused to materials and reducing the risk to human health. For peace of mind, all our windows meet or exceed industry standards.
Because glass blocks the majority of UVB rays responsible for burning the skin, in most cases, you won’t get sunburn through standard window glass.
However, UVA rays can still pass through windows, which means prolonged exposure to sunlight indoors can still contribute to skin damage and ageing over time.
Large glazed areas like conservatories and roof lanterns let UVA rays through, so if you sit in direct sunlight indoors for long periods, your skin is still exposed. In those situations – especially if you’re sensitive to UV – wearing sunscreen can make sense.
While some UV exposure can occur through glass, it’s minimal; so you’re unlikely to tan indoors, even in direct sunlight.
Tanning and burning are mainly caused by UVB radiation, which is largely blocked by standard window glass. Because UVA rays can still pass through, they may contribute to slight skin darkening over time, but the effect is much weaker.
Double glazing provides better UV protection than single-pane windows, although it doesn’t eliminate UV exposure.
Modern double-glazed windows often include additional features that help reduce UV transmission, such as:
Many modern replacement windows also provide improved thermal efficiency and UV protection at the same time.
Our windows are A+ rated for efficiency, reducing heat loss and improving protection against UV exposure compared to older glazing. Explore our range of windows to learn more.
Even if UV exposure indoors seems minimal, sunlight entering through windows can have noticeable effects over time.
UV radiation can cause materials to fade, particularly:
Rooms with large windows or conservatories often experience the most noticeable fading.
Although indoor exposure is much lower than direct sunlight, UVA rays can still affect the skin over long periods of time. This is why dermatologists often recommend UV protection even when indoors near large windows.
Homes with conservatories often experience higher levels of sunlight exposure due to the large areas of glass.
Modern glazing solutions used in conservatories can help manage heat and UV transmission, improving comfort throughout the year.
If you’re replacing your windows or upgrading glazing in your home, certain glass types offer better UV protection.
Laminated glass includes a special interlayer between two panes of glass. This layer can block a very high percentage of UV radiation while also improving safety and security.
Low-emissivity coatings reflect heat and reduce the amount of UV radiation passing through the glass.
These coatings are commonly used in modern energy-efficient windows.
Upgrading older windows to modern double glazing can significantly improve:
Yes, window glass blocks most UVB radiation, which causes sunburn. However, a significant amount of UVA radiation can still pass through standard glass.
Double-glazed windows generally provide better UV protection than single-pane glass, particularly when combined with modern coatings or laminated glass.
Yes. UV radiation entering through windows can cause furniture, flooring and fabrics to fade over time.
Laminated glass provides some of the best UV protection and can block up to 99% of UV radiation.
Conservatories often receive more sunlight due to the large areas of glazing. Modern conservatory glass can include coatings and technologies designed to reduce UV transmission.