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Last updated: 09 June 2021

Find the Best Double Glazed Windows

The Ultimate Guide for Double Glazed Windows

Is the noise outside driving you mad? Is your home still cold in the wintertime even though your heating bills are through the roof? Then double glazed windows are the solution for you!

The benefits of having double glazed windows are numerous and worth every pound.

Double glazing in your windows helps you insulate your home better, therefore they are an essential part of any building. Choosing the right windows can make a huge difference in how functional and comfortable that building will be.

1 1: Double glazed windows limit the amount of direct sunlight coming into your house thereby protecting your furniture and carpet, which can fade with direct sunlight. 2 2: Solar transmission is reduced significantly through double glazed windows. 3 3: Double glazed windows are highly energy efficient as they provide insulation to reduce heat transfer from inside the house to the cold air outside. Similarly, they keep the heat outside during hotter months. This is a great advantage in both summers and winters. 4 4: Double glazed windows significantly reduce external noise and disturbance to provide a calm environment inside the house.
Double Glazed Windows

Double glazed windows can have different frame styles, so you can adapt them to your modern home. The frame of your windows can either be wood, aluminium or if you're after a more affordable solution, uPVC windows.

Starting Prices of Double Glazed Windows
Number of windows Window style Price of Windows
1 Casement windows from £300
1 Tilt and turn windows from £500
1 Sash windows from £600

At GreenMatch, we assist you in deciding if double glazed windows are the right investment for you. If you would like to get a quote on new windows, just fill out the form at the top of this page and we'll make sure to provide you with quotes from our trusted suppliers.

What Is a Double Glazed Window?

Double glazed windows are frames fitted with two panes of glass that have a space between them, usually 12mm to 16mm. The gap between the two glass panes stays in place thanks to a spacer bar. Typically, this gap is filled with normal air, but it can also be filled with argon gas.

This method of double glazing is also called insulated glazing because of the ability to trap the air between the panes glass which leads to dramatic reductions of heat and noise transmissions.

Hence, the more layers of glass the window is built with, the higher the reduction is going to be. However, the glazing method is not limited to only two layers of glass, triple glazing is also available for even more optimal results. Thus, no matter how good of a heating system you rely on to warm your house, it is useless if most of the heat is lost through a single-pane window.

It is expected that double glazing will continue to rise in popularity followed by energy efficient incentives and other products available on the market. With the wide variety of choice nowadays, not only does double glazing improve your home, but it also reduces your carbon footprint at the same time. Find here more information about prices of double glazing products.

DOUBLE GLAZING  - What is it and how does it work? │GreenMatch

What Is the Cost of Double Glazed Windows?

There are several factors to take into account when it comes to the cost of double glazed windows. How many windows you need and the style that fits your home is what should be considered first. Additionally, the material of the frames and glass type will help determine the final price, since different materials and glass types cost different amounts.

Regarding the frame material, PVC is used the most for double glazing because of its efficiency and low price. Aluminium and wooden frames, on the other hand, are more costly and are not more functional than the uPVC substitute.

As for the style/type of the double glazed windows, the most popular are casement and sash. Casement windows are generally the cheapest option, contrary to the dual turn which is considered to be most expensive.

Cost of Casement Windows
Number of bedrooms Number of white uPVC casement windows
(600mm x 900mm)
Average cost
2 4 windows from £1,000
3 9 windows from £2,250
4 15 windows from £3,750

A single casement white uPVC window (600mm x 900mm) usually costs around £250 in the UK. On the other hand, a single sash white uPVC window (600mm x 900mm) is estimated to cost approximately £500.

Since casement and uPVC sash windows are the most popular in the UK, we created the tables below to provide an approximate price estimation of these types of double glazed windows. The prices are offered is according to the type and number of double glazed windows.

Please keep in mind, that these numbers may not represent an actual offer, it is only an approximate estimation to give you an idea of the total cost.

Cost of Sash Windows
Number of bedrooms Number of white uPVC sash windows
(600mm x 900mm)
Average cost
2 4 windows from £2,000
3 9 windows from £4,500
4 15 windows from £7,500
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Types and Longevity of Double Glazed Windows

Depending on your specific requirements, double glazing companies can supply all sorts of double glazed windows to meet your needs.

You can even choose your windows according to the type of glass, window frame material and shape, type of spacer bar, and what the space between the glasses will be filled in with.

Double Glazed Window Types

Different Types of Glass

1. Low E-energy Saving Glass

The glass used in a double glazed window for thermal insulation is called Low-E, or low-emissivity glass. This type of glass is the best for cold regions where a lot of energy is used to heat the house. Hence, this type of glass is energy efficient and will help reduce your heating bills.

2. Acoustic Glass

Acoustic glass has been developed to lessen the levels of unwanted noise from the outside. It is built of two or more sheets of glass that are bonded together with one or more acoustic interlayers. These layers weaken the sound waves as they travel through the glass.

3. Self-Cleaning Glass

the technology of uPVC windows has developed so far, that nowadays you can purchase double glazed windows that can be cleaned by themselves. Self-cleaning glass is pre-coated with a transparent coating that works to break down the dirt and spread water evenly around the surface.

4. Safety Glass

In order to avoid injuries caused by broken glass, toughened and laminated forms of glass have been developed. If they break, they will not form dangerous shards and splinters in the same way that standard glass will.

5. Fire Glass

In order to get protected from fire or smoke, this type of glass is the most optimal solution. The toughening, laminating, and coating technologies used, makes this glass more resistant to impacts and provides a barrier that gas, flame, and smoke cannot pass.

6. Security Glass

This glass, offers, even more, protection than safety glass and can protect from vandalism, infraction or any type of aggression towards your home. The way it is manufactured is what creates this glass’ unique ability to act as a protector.

7. Decorative Glass

The glass used for double glazing can be manufactured in a variety of ways to offer different choices of patterns, colours, texture, and opacity. This type of glass can be combined with some of the previous types to improved functionality.

8. Solar Control Glass

The purpose of the solar control glass is to reflect and filter the sun’s rays, allowing natural light in the room, without causing discomfort from visual glares. This can be very beneficial for glass roofs or any building with large glazed areas.

Apart from being very functional on its own, most of the glass types can be combined together for a targeted purpose, hence to fulfil any individual needs.

Double Glazed Framing Material

Types of Frame Materials

Usually, double glazed window frames are made of timber, aluminium or PVC (plastic derivative). It is very important to choose the right frame, as this will affect the insulation properties of the window by up to 30 %.

PVC Frames

Also called uPVC, is the most widely used material when it comes to double glazed windows. The reason for this is that uPVC frames are usually the lowest cost option, but they still provide an excellent insulation and require very little maintenance. Not only that, but these frames come in many different colours and finishes. The only downside is that they can suffer from expansion under strong sunlight;

Timber Frames

Timber frames are made from different types of hardwood. They give the home a traditional look and are very durable. Usually, they are stained and varnished instead of painted. However, even though very attractive, they are more expensive than the uPVC double glazed window frames and require more maintenance;


Double glazed frames are least popular mainly because of their high price and poor insulation properties. Nevertheless, the advantages of this material are that they are strong, secure, low maintenance, and are expected to last for a very long time.

Spacer Bars

A spacer bar is the continuous hollow frame that is used to separate the two glass panes in the double glazed windows. The spacer bar is an important element of the double glazed windows unit and is typically made of aluminium or low-heat-conductive material (warm-edge spacer).

The aluminium spacer bars are currently the most often used because they are cheap, light, flexible, and very strong. The warm-edge spacers are however more effective when it comes to insulating against heat.

Besides the type of material that the double glazed windows are made of, double glazing companies have created a range of shapes and styles in order to fit any home. The most popular are:

  • Bay and bow windows
  • Round Window
  • Tilt and Turn windows
  • Fully reversible windows
  • Cottage windows
  • Casement and replacement casement windows
  • Sash windows
  • Secondary windows
  • Dual turn windows

Glazed windows for homes: double, single and triple glazed

Advantages of Double Glazed Windows

  • Lower energy bills
  • Safe and warm house
  • Noise reduction
  • Furniture is safe
  • Increase house value
  • Reduce carbon footprint

1. Lower Energy Bills

Statistics show that nearly 50 to 70 percent of the heat from our homes is lost through single glazed windows. Since double glazed windows have the opposite effect, they will help you save on your energy bills.

2. Home Safety

Did you know that double glazed windows are much stronger than the single glazed windows? This helps make double glazed windows more secure, as the toughened glass is much harder for burglars to break.

3. Peaceful Home

Double glazed windows are able to reduce up to 60% of the outside noise from coming in. This is especially important for those who live close to busy urban areas.

4. Keeps Your Furnishing Safe

if some furniture is exposed to too much sunlight, the heat can begin to damage them. Double glazed windows, however, limit the amount of direct sunlight and heat that comes into your house, thus eliminating the risk of your furniture, paintings, carpet, and other objects around home becoming damaged.

5. Increase House Value

A house with double glazed windows installed has a higher value than those without. Therefore, double glazed windows are an efficient investment not only for the reasons mentioned above but also in a long-run, in case you decide to sell your home in the future.

6. Reduce Your Carbon Footprint

Double glazing can significantly reduce the emissions of greenhouse gas (GHG) from heating and cooling, and that will reduce your carbon footprint on the Earth.

Disadvantages of Double Glazed Windows

  • Less appealing with older architecture house
  • High initial cost
  • Can not be repaired
  • Heat is trapped

1. Trapped Heat

While this characteristic of the double glazed windows is what makes them so unique and functional in the cold seasons, it can have the opposite effect in summer. To fix this problem, you have the option to tint your windows, but that may add to the overall cost.

2. Can’t Be Repaired

Double glazed windows can not be fixed. If the seal of the window is not airtight, condensation can appear between the glass panes. As the windows are already sealed, they can not be pulled apart in order to fix the problem. The only solution is to repair the whole window.

3. Do Not Match Well with Older Homes

If you have a house that is built in older architectural style, these windows might not blend with the overall aesthetic of the house. However, there are some double glazing companies that produce double glazed windows specifically for these types of houses.

4. The Initial Cost

Since double glazed windows contain two glass panes, and thus more material is used to produce them, their cost increases by default. Though, this should not be of a high concern if you first consider the amount of savings you’ll have in the long run. Hence, double glazed windows are very likely to be a worthwhile investment for anyone.

How Do Double Glazed Windows Work?

Single glazed windows are designed to let the light in while blocking air and objects from entering the house. They are only a few millimetres thick, hence heat can easily flow through them, making it harder to heat or cool the house. Double glazed windows, on the other hand, let the light in while insulating your home from the outside elements

Components of Double Glazed Windows

There are 6 main components of a double glazed windows unit: the glass pans, the primary seal, the secondary seal, the cavity, and the spacer bar. Additionally, often there is a desiccant between the panes in order to absorb any moisture and to stop fog from forming between them. Furthermore, the windows can be either transparent, tinted, or layered with a reflective coating.

Double Glazed Window Components

Double glazed windows insulate in several different ways. Firstly, having two glass panes makes it more difficult for the heat to escape.

Second, and most important, is the trapped air between the glasses because of the insulation power it produces.

Since heat is the rapid movement of molecules (the hotter a material is, the faster molecules move) when excited molecules move and collide with other molecules the heat is then spread out. This process is called conduction. As a result of this process, the air between the glass panes act as an insulator and makes it very difficult for the heat to escape outside.

The purpose of the coatings (tinted, reflective) is to prevent the sun from heating up the room, for instance, or to reduce the light coming in.

Double Glazing Window Repairs

Double glazed windows should last many years before needing any kind of repair or replacement. However, there are two tell-tale signs you might need your double glazed windows repaired.

  1. If you notice your comfort levels decreasing. For example, if they are leaking, you will notice a draught coming through. This will result in higher energy bills because heat is lost quicker. Also, if there is increased noise coming in from the outside, it could be that they are leaking.
  2. If you see physical damage on them. This could be a broken seal, if they are difficult to open, or if they are changing colour.

If you have noticed that your windows need repairing—or you may be looking for outright replacement windows—then you should either contact the installer or you can look for a new one. If you want new double glazing, you can use GreenMatch's quote comparison service.

Your windows will inevitably need to be repaired or replaced, but it is important to take proper care of them to prolong their lifespan.

FAQs About Double Glazed Windows

What is double glazing?

Double glazed windows are highly energy-efficient and are an investment to lower your energy costs as they add a layer of insulation, which not only preserves energy but also has an added benefit of reducing external noise entering the house. 

They are windows with two panes of glass that have a small space between them, typically 12-16mm. The space in this gap can either consist of air or argon gas. Essentially, this space traps air between the glass panes to prevent any air from leaking out, which means you can trap more heat in your home an have a better-insulated house. 

Are double glazed windows worth it?

Double glazed windows are an excellent way to insulate your home and reduce your utility costs. The double-paned glass stops air from leaking out, which helps improve your home's energy efficiency, meaning you won't need to spend as much money heating it up.

In addition, the insulating effect will keep out noise from the outside. This is particularly advantageous if you live in a noisy area or close to main roads.

What are the best types of double glazed windows?

There are many different types of glass and frames for double glazed windows that come with multiple benefits suited specifically to your home. 

When it comes to frame types, are a popular, affordable choice because of their energy-efficiency, weather resistance, and sturdiness. Other options include wooden or aluminium windows.

How much are double glazed windows?

Double glazed windows can start from as low as £300 for one window and go up to £1,500 in the UK. Double glazed windows prices vary based on the type and quality of double glazing. 

Can I get a grant for double glazing?

The UK government has announced that double glazing is now an eligible secondary measure of home improvements. Therefore, homeowners are eligible to apply for the grant when upgrading to double glazing. You can read further details about the grant here.

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Valli Vishnubhotla
Written by Valli Vishnubhotla, Digital PR Manager

Valli is the Digital PR & SEO Manager at GreenMatch. She has an educational background in business management and marketing. She is a passionate digital marketer and enjoys building her skills within SEO, online marketing and PR. She holds 5 years of experience in creating content, B2B marketing, link building and digital networking. Her focus lies in the areas of business, marketing, green energy and sustainability, to name a few. Her work has been published in various media such as Entrepreneur, Business Insider, Creativebloq, Designtaxi, and more.