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 installing double-glazed windows may be a solution for you!
The benefits of having double-glazed windows are numerous and worth every pound. Double glazing helps you insulate your home better; thus, choosing the right windows can make a huge difference in comfort and functionality.
However, the right fit will ultimately depend on your own needs. By reading this review, you will learn all you need to know to answer that question you have been pondering: what are the best double-glazed windows for my home?
Double-glazed windows come in different styles so that you can adapt them to your modern home. There are also different materials to choose from for the frame. You can either pick between wooden, aluminium or uPVC windows.
According to our research, prices for double-glazed windows start at about £300, excluding installation costs. The actual cost of the best double-glazed windows in the UK may vary considerably depending on the style, size, material and colour of the frame.
I want to find the best double-glazed windows near me! At GreenMatch, we assist you in finding double-glazed windows at the best price. We do this by saving you time and sending you up to 4 offers that are tailormade to your requirements from suppliers in your area. You can then objectively compare prices and lock in the best deal. Just select your region below.
Learn More in Our Guide
- What Is a Double-Glazed Window
- How Do Double-Glazed Windows Work?
- Types and Longevity of Double-Glazed Windows
- What is the Cost of Double-Glazed Windows in the UK?
- Double-Glazed Window Repairs
- Advantages of Double-Glazed Windows
- Disadvantages of Double-Glazed Windows
- FAQs about Double-Glazed Windows
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. Thanks to a spacer bar, the gap between the two glass panes stays in place. Typically, this gap is filled with regular air, but it can also be filled with argon, xenon, or krypton gas.
This method of double glazing is also called insulated glazing because of the ability to trap the air between the panes of glass, leading to dramatic reductions in heat and sound transmissions.
However, the glazing method is not limited to only two layers of glass. Triple glazing windows are also available on the market. Both double-glazed and triple-glazed windows have great results, though the more layers of glass the window has, the higher the reduction of heat loss and noise. In any case, no matter how good or sophisticated your heating system is, you can’t make the most of it if the heat is lost through a single-pane window.
It is expected that double glazing will continue to rise in popularity alongside energy-efficient incentives and other products available on the market. Considering the wide variety of frame materials and types of glass available, not only do double-glazed windows improve your home, but they can also reduce your carbon footprint. Find more information about the prices of double glazing products in the UK.
How Do Double-Glazed Windows Work?
Single-glazed windows are only a few millimetres thick. Heat can easily flow through them, making it harder to keep the ideal temperature in your home. On the other hand, double-glazed windows let the light in while insulating your home.
Heat flows spontaneously from a hotter body to a cooler one. The air between the window’s panels acts as an insulating barrier between the inner (hotter) pane and the outer (cooler) one. As a result, it is more difficult for the heat to escape from your home to the outside.
Some double-glazed windows may need trickle vents fitted at their top. These are designed to allow fresh air to circulate through a room and reduce condensation between the glass panes. According to our experts at GreenMatch, trickle vents do not significantly affect noise reduction or increase heat loss when used correctly.
Watch how double glazing windows prevent heat loss and reduce noise in this 2-min video:
Components of Double-Glazed Windows
A double-glazed window unit has 6 primary components: the glass panes, the primary seal, the secondary seal, the cavity, and the spacer bar. Additionally, there is often a desiccant between the panes to absorb any moisture and stop fog from forming between them. Furthermore, the windows can be either transparent, tinted, or layered with a reflective coating. The purpose of the coatings is to prevent the sun from heating up the room or reduce the light coming in.
Types and Longevity of Double-Glazed Windows
You can choose your new double-glazed windows according to the type of glass, window frame material and shape, type of spacer bar, and what the space between the glass panes will be filled in with.
Modern windows all carry rating labels issued by competent British organisations highlighting their energy efficiency level. While the labels include scores from A to G, a window rated C is the lowest you can fit and still meet building regulations in the UK.
What are the best double-glazed windows? Well, all different types have different benefits. You will find out reading below.
Different Types of Glass
Besides being very functional on their own, most glass types can be combined to fulfil a specific need.
The following are the best double glazing glass for different purposes:
1. Low-E or energy Saving Glass
Low-E, low-emissivity, or energy-saving glass is the best for cold regions where much energy is used to heat the house. Windows made out of this type of glass are probably the most energy-efficient windows. It will help you reduce your heating bills for sure.
2. Acoustic Glass
Acoustic glass has been developed to lessen unwanted noise levels 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. It is considered the best double glazing for noise reduction purposes.
3. Self-Cleaning Glass
The technology of uPVC windows has developed so much that, nowadays, you can purchase self-cleaning double-glazed windows. 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
Safety glass is less likely to break or to cause injuries if broken. The most common safety glass designs for windows are toughened glass and laminated glass. The first one is processed to increase its strength. When broken, it crumbles into small, less dangerous granular chunks. On the other hand, laminated glass is composed of layers of glass and plastic. Broken glass pieces are held together by an interlayer. This design also offers better sound insulation than standard glass.
5. Fire Glass
This type of glass is the best option to get protected against fire or smoke. Toughening, laminating, and coating technologies make this glass more resistant to impacts and create a barrier that gas, flame, and smoke cannot pass.
6. Security Glass
Security glass offers even more protection than safety glass against vandalism or aggression towards your home. These panes range in thickness from 7.9mm to 18mm and can resist attacks with hammers, screwdrivers, bricks and axes for 1-2 minutes.
7. Decorative Glass
The glass used for double glazing can be manufactured in various ways to offer different choices of patterns, colours, texture, and opacity. Decorative glass is the best for giving your home that personal design touch you want. It can be combined with some of the types mentioned above to improve functionality.
8. Solar Control Glass
The special feature of the solar control glass is to reflect and filter the sun’s rays, allowing natural light in the room without causing discomfort from glares. It can be optimal for any building with large glazed areas.
Types of Frame Materials
Usually, double-glazed window frames are made of timber, aluminium or uPVC (unplasticised polyvinyl chloride). It is essential to choose the proper structure, as this will affect the window's insulation properties by up to 30%.
1. uPVC Frames
uPVC is the most widely used material when it comes to double-glazed windows. This is because uPVC frames are usually the lowest cost option. However, they still provide excellent insulation and require very little maintenance. Furthermore, these frames come in many different colours and finishes. The only downside is that they can suffer from expansion under intense sunlight.
2. 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.
Aluminium frames are the least popular mainly because of their high price and lesser insulation properties. Nevertheless, they have some significant advantages: they are strong, secure, need low maintenance, and are expected to last for a very long time.
A spacer bar is the continuous hollow frame used to separate the two glass panes in the double-glazed window. The spacer bar is an essential element of the double-glazed windows unit and is typically made of aluminium or low-heat-conductive materials (warm-edge spacer).
Aluminium spacer bars are currently the most often used because they are cheap, light, flexible, and strong. The warm-edge spacers are, however, more effective for insulation purposes.
Besides the type of glass and materials that the double-glazed windows are made of, double glazing companies have created a range of shapes and styles to fit any home and preference. The most popular are:
- Casement and replacement casement windows
- Double-glazed sash windows
- Tilt and Turn windows
- Dual turn windows
- Fully reversible windows
- Bay and bow windows
- Round Windows
- Cottage windows
- Secondary windows or secondary glazing
How Long Do Double-Glazed Windows Last?
Double-glazed windows can last from 10 to 50+ years, though their longevity depends on how well they were made, installed and maintained. For instance, timber double-glazed windows may require extra care to keep the paintwork or varnish optimal. Similarly, poor quality seals may perish and allow draughts after approximately a decade.
However, according to the best double glazing companies in the UK, double-glazed windows should last for at least 20 years on average if adequately maintained. These companies also provide long-term guarantees between 10 to 12 years.
In this guide, you will also find tips on how to recognise that your windows might need replacement or repair.
What is the Cost of Double-Glazed Windows in the UK?
Prices of double-glazed windows vary depending on the style, material, and size. Other factors may also affect your final bill, for instance, the number of windows, type of glass, frame colour, the floor where you want to install the window (e.g. ground floor vs the second floor), installation and potential delivery costs.
When it comes to the frame material, uPVC is the more affordable one. On the other hand, aluminium and wooden frames are more costly and not much more functional than the uPVC substitute.
As for the style, casement and sash windows are the most popular. Generally, casement windows are the cheapest option, while dual turn windows are the most expensive.
Starting Prices of Double-Glazed Windows
Prices for double-glazed windows in the UK start at about £300, excluding installation costs. Considering that getting your windows fitted by an expert may cost you an extra £200-£250, at GreenMatch, we estimate that the starting price is between £500 and £600 per window.
Including installation costs, the starting price of a double-glazed casement window would be around £560; for a sash window, £650; and £760 for a tilt & turn window. Also good to know that uPVC sash windows are the most popular in the UK.
Check the tables below for a price comparison among different window styles and frame materials. Please, keep in mind that these numbers may not represent an actual offer. They are only an estimation to give you an idea of the cost, including installation.
Cost of Double-Glazed Casement Windows
|Frame material||Average cost per window (100cm x 100cm)|
Cost of Double-Glazed Sash Windows
|Frame material||Average cost per window (100cm x 100cm)|
Cost of Double-Glazed Tilt & Turn Windows
|Frame material||Average cost per window (100cm x 100cm)|
At this point, you might be wondering: Are double-glazed windows worth it? Short answer: Yes!
Besides the many advantages they have when it comes to making your home more comfortable, you could save up to £145 per year on your bill by switching to double glazing with an energy efficiency of A+. Moreover, double-glazed windows can increase a property’s market value by up to 10%.
Curious about how much you can save with double glazing windows? Just select your region below.
Double Glazing Window Repairs
Double-glazed windows should last many years before needing any repair or replacement. However, there are two tell-tale signs you might need your double-glazed windows repaired or replaced.
- If you notice your comfort levels decreasing. For example, if your windows are leaking, you will feel a draught coming through them. 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 indicate that they are leaking.
- If you see physical damage on them. This could be, for instance, a broken seal, condensation between the panes, changing colour, or if they become more difficult to open.
If you have noticed that your windows need repairing —or you may be looking for outright replacement windows— you should contact the installer or look for new ones. You can use GreenMatch's quote comparison service if you want new double glazing.
In any case, it is always a good idea to take proper care of your double-glazed windows to prolong their lifespan and keep them looking their best.
Advantages of Double-Glazed Windows
1. Lower Energy Bills
- Lower energy bills
- Safe and warm house
- Noise reduction
- Furniture is safe
- Increase house value
- Reduce carbon footprint
Around 50 to 70% of the heat from our homes could be lost through single-pane windows. Since it is more difficult for the heat to escape through a double-glazed one, this kind of window helps you save up to £145 per year on your energy bills.
2. Home Safety
Double-glazed windows are much stronger than single-glazed windows. Even if double glazing is not unbreakable, different types of glass (e.g. safety and security glass) can make your double-glazed windows much harder for burglars to break.
3. Peaceful Home
Double-glazed windows can reduce up to 60% of the outside noise coming in. This is especially important for those living close to busy urban areas.
4. Keeps Your Furnishing Safe
If some furniture is exposed to too much sunlight, the heat can damage them. Double-glazed windows, however, limit the amount of direct sunlight that comes into your house, reducing, thus, the risk of your furniture, paintings, carpet, and other objects getting damaged.
5. Increase House Value
A house with double-glazed windows installed has a higher value than those without them. Therefore, double-glazed windows are an intelligent investment in the long run if you decide to sell your property.
6. Reduce Your Carbon Footprint
Double glazing units have better energy efficiency. They can also significantly reduce greenhouse gas emissions from heating and cooling. Consequently, you will reduce your carbon footprint on the Earth.
What Are the Disadvantages of Double-Glazed Windows
1. Trapped Heat
- Less appealing with older houses
- High initial cost
- Can’t be (easily) repaired
- Heat is trapped
Double-glazed windows are very functional in the cold seasons; however, trapped heat could be a problem in summer. Tinting your windows or having trickle vents could solve this problem.
2. Can’t Be Repaired
Double-glazed windows cannot be fixed so easily. If the window seal is not airtight, condensation can appear between the glass panes. As the windows are already sealed, they can not be pulled apart to fix the problem. The only solution is to repair the whole unit. However, condensation can be prevented by, for instance, having trickle vents fitted at the top of the windows.
3. Do Not Match Well with Older Homes
If you have a house built in an older architectural style, these windows might not match the overall aesthetic. Nevertheless, some double glazing companies produce double-glazed windows specifically for this type of house.
4. The Initial Cost
They are more expensive than single-pane windows because they contain two glass panes and, in some cases, special components. Though, our advice at GreenMatch is that investing in double-glazed windows is worth it.
FAQs About Double-Glazed Windows
It depends on what you want to achieve with your double-glazed units. Despite being versatile and very functional on their own, every type of double glazing glass is designed to have the most effective performance for a specific purpose. For instance:
- Low-E or energy-saving glass is the most effective for cold regions. It is probably the most energy-efficient glass for double glazing.
- Acoustic glass is the most effective for noise reduction purposes.
- Security glass is the most effective in protecting against vandalism, burglary or aggression towards your home.
- Decorative glass is the most effective for personalised home design.
The best window is the one that best meets your needs. You can choose your new double-glazed windows according to the type of glass, window frame material and shape, and what the space between the glass panes will be filled in with (e.g. dry air, argon gas).
In this regard, double glazing companies can supply all sorts of windows based on your specific requirements. If you want to learn more about it, you can read GreenMatch’s review of the top double glazing companies in the UK.
Concerning the frame material, uPVC windows are the most affordable ones. On the other hand, casement and sash windows are the most popular styles. Also good to know that uPVC sash windows are the most common choice in the UK.
Triple-glazed windows are better than their double-glazed counterparts when it comes to energy efficiency. They are the most energy-efficient glazing option on the market.
These windows should make your home warmer and more sound-proof than double-glazed windows. Nevertheless, they are considerably more expensive. If you want to install these in your house but their cost is prohibitive, you may consider triple glazing just for the coldest rooms or those that suffer the most from outside noise.
Windows made out of Low-E glass are probably the most energy-efficient windows.
In the UK, modern windows all carry rating labels issued by competent British organisations, which highlight their energy efficiency level. While the labels include scores from A (or even A++) to G, a window rated C is the lowest you can fit and still meet building regulations in the country.
Windows energy rating labels are issued by either one of these three organisations:
The Green Homes Grant closed to new applications on the 31st of March 2021 at 5 pm. The scheme was previously extended to the end of March 2022. But in a new press release from the government, they announced that the applications would end a year early on the 31st of March 2021.
However, other alternative grants are available in the UK to incentivise the transition to green living. Read more about other active government grants.
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