Types of glass for double glazing explained

Choosing new windows is about more than frames and colours. The glass itself affects how warm, quiet, private and secure your home feels. With several types of glass available, understanding what each one does can help you choose the right option for your property.

At Advanced Glazing Systems, we have over 20 years of experience helping homeowners across Essex and London choose double glazing. This guide explains the main types of window glass, where they are typically used and what to consider when comparing your options.

How does double glazing work?

Before looking at different types of glass, it helps to understand how a double-glazed window is constructed. A few terms often appear in glazing quotes, including insulated glass units, spacer bars and gas fills.

What is an insulated glass unit?

An insulated glass unit (IGU), also called a sealed unit, is the glass section fitted into your window frame. It consists of two glass sheets separated by a spacer bar and sealed around the edges. This creates an air gap between the panes, helping to slow heat transfer.

The sheets are usually made from float glass, manufactured by floating molten glass on a bath of molten tin to create a smooth, even surface. If a sealed unit fails and condensation develops between the glass layers, it can usually be replaced without changing the entire window.

What do argon gas and warm-edge spacers do?

Some double-glazed units contain argon gas between the glass panes. This clear, odourless gas transfers heat less readily than air, helping to improve thermal insulation and reduce heat loss. Overall performance also depends on the glass, spacer and window frame. The spacer bar keeps the panes apart around the edge of the glass unit. Warm-edge spacers use materials that conduct less heat than traditional aluminium, helping to keep the glass edges warmer and reduce the risk of condensation.

Understanding window energy ratings

The British Fenestration Rating Council (BFRC) rates windows from A++ to E, considering the performance of the complete window, including heat loss, solar gain and air leakage. A U-value is another measure of thermal performance: the lower the figure, the better the insulation.

At AGS, our standard double glazing achieves a U-value as low as 1.4 W/m²K. We also offer A+12 and triple glazing options for homeowners looking for additional thermal performance. The exact specification and performance depend on the window system selected.

The Energy Saving Trust estimates that installing A-rated double glazing in an entirely single-glazed, gas-heated semi-detached home could save around £85 a year on energy bills in Great Britain. Actual savings vary between properties.

Different types of window glass explained

Different types of glass serve different purposes. Some focus on energy efficiency, while others offer privacy, extra security or noise reduction. Some options describe how the glass is manufactured, while others involve coatings or specialist interlayers. They can sometimes be combined within the same double-glazed unit, depending on the required specification.

Low-E glass

Low emissivity (Low-E) glass has a very thin, transparent coating that reflects heat back into the room while allowing natural light through. This helps reduce heat loss and supports better temperature control during colder months.

Our glazing options can feature a Low-E coating, which helps reflect heat back into your home.

• Best for: Living rooms, bedrooms and other spaces where thermal insulation is a priority.
• Worth knowing: Low-E glass helps retain indoor warmth. Rooms that receive strong sunlight may also benefit from solar-control glazing, which can combine solar control with low-emissivity performance.

Toughened safety glass

Toughened glass is heated and rapidly cooled during the manufacturing process, making it stronger than regular glass. If it breaks, it crumbles into small, relatively blunt pieces rather than large, sharp shards, reducing the risk of injury.

• Best for: Glazed doors, low-level window glass and large glass panels where safety is important.
• Worth knowing: Building Regulations identify critical locations where glazing must meet specific safety requirements. These include certain low-level windows, glazed doors and adjacent side panels. Suitable toughened or laminated glass can help meet these requirements, depending on the location and specification. Toughened glass cannot be cut or drilled after manufacture, so each pane must be made to the correct size.

Laminated glass

Laminated glass bonds two or more layers of glass together with a plastic inner layer, usually polyvinyl butyral (PVB). If the laminated pane breaks, the fragments tend to remain attached to this layer rather than falling away.

This can make it harder for potential intruders to get through quickly. Depending on the specification, the interlayer can also help reduce the amount of ultraviolet light entering your home.

• Best for: Ground-floor windows, front doors and areas where extra security is a priority.
• Worth knowing: Laminated glass is not unbreakable. It can crack and will still need replacing if damaged.

Acoustic glass

Acoustic glass is designed to improve noise reduction. It often uses laminated glass with a specialist sound-dampening interlayer, sometimes alongside panes of different thicknesses to limit sound transmission. It can be specified across window styles, including casement, tilt-and-turn and sash windows.

Our standard windows provide 31 dB sound insulation, while our premium sound-reducing glass achieves up to 36 dB.

• Best for: Bedrooms and living rooms overlooking busy roads, railway lines or flight paths.
• Worth knowing: The frame, seals and quality of installation also influence acoustic performance.

Obscure or patterned glass

Obscure glass has a textured or patterned surface that allows natural light into a room while blurring the view. Different designs provide different levels of privacy, from subtle distortion to heavily obscured finishes.

• Best for: Bathrooms, en-suites, cloakrooms and glazed door side panels.
• Worth knowing: Privacy varies between patterns. Obscure glass can also be combined with toughened or laminated safety glass where required.

Self-cleaning glass

Self-cleaning glass has a special coating on its external surface. Daylight helps break down organic dirt, while rainwater spreads across the glass and washes away loosened deposits.

• Best for: Roof glazing and roof lanterns, particularly where external glass is difficult to reach.
• Worth knowing: It reduces cleaning rather than removing it altogether. The coating works best with access to daylight and rain, and occasional maintenance may still be needed.

Solar control glass

Solar control glass uses a specialist coating to reflect or absorb part of the sun’s energy before it enters your home. This reduces solar heat gain and can help rooms with large windows or glass doors stay more comfortable during warmer weather.

We also offer solar control glass options for our roof lanterns.

• Best for: South- and west-facing rooms, large glass panels and conservatories that become uncomfortable in summer.
• Worth knowing: The appearance and amount of daylight passing through vary between products. Reducing solar heat can also mean less free warmth from the sun during winter.

Which type of glass is best for your home?

There is no single best choice for every property. The right glass depends on the room’s position, how you use the space and whether warmth, privacy, security or noise reduction matters most.

• Bathrooms and en-suites: Obscure glass provides privacy while allowing daylight in.
• Patio, bifold and French doors: Toughened or laminated safety glass may be suitable, depending on the location and specification.
• Bedrooms facing busy roads: Acoustic glass can help reduce external noise.
• South-facing living rooms: Solar control glass can help manage heat from direct sunlight.
• Hard-to-reach windows: Self-cleaning glass can reduce maintenance, particularly on roof glazing.
• North-facing rooms: A suitable high-performance glazing specification can help limit heat loss. Triple glazing may be worth considering for additional thermal insulation.

What about integral blinds?

Integral blinds sit between the panes of an insulated glass unit, protecting them from dust and everyday damage. They offer a convenient way to manage light and privacy without fitting conventional blinds inside the room.

We offer integral blinds for suitable windows and doors.

Talk to us about your glass options

Choosing between different types of glass does not have to be complicated. Our team can explain the available options and help you compare their benefits based on your home and requirements. Think about which rooms become too hot, where you need more privacy and whether outside noise is a concern. These details will help us recommend a suitable glazing specification.

We’re members of the Glass and Glazing Federation (GGF), registered with FENSA and accredited by TrustMark.

Visit our Upminster showroom, book a video appointment or contact our team for a free, no-obligation quote.

Call us on 01277 230101 or email sales@advancedglazingsystems.co.uk to find out more.