In this article, readers will learn about secondary glazing and double glazing, their definitions, and how they work. The installation process of both options will be discussed, including time, cost, and skills required. The noise reduction mechanism of secondary and double glazing will be examined and compared through determining factors such as thickness of glass, air gap, and seals.

The article also presents a comparative analysis of noise reduction performance, pros and cons of secondary and double glazing, and other benefits like thermal insulation, energy efficiency, security, and condensation control. Lastly, the article provides guidance on choosing the right option for one’s needs, considering noise reduction requirements, cost, installation factors, and seeking professional advice.

Noise Reduction Comparison Between Secondary Glazing and Double Glazing


Table of Contents

Understanding Secondary Glazing and Double Glazing

Definition of Secondary Glazing

Secondary glazing consists of installing a secondary window on the inside of an existing single-glazed window. The main purpose of this system is to provide additional insulation and noise reduction. Secondary glazing is often an ideal solution for properties where the installation of double glazing is not feasible or permitted. This is usually due to historical or architectural constraints, such as listed buildings and conservation areas.

The secondary window comprises one or more glass panes attached to a frame that matches the existing window’s profiles. The installation process involves adding a fully independent, slim-line window frame to the existing window’s inner side. Seals are used between the primary and secondary window frames to prevent drafts and provide thermal insulation.

Definition of Double Glazing

Double glazing consists of two layers of glass separated by a space filled with inert gas, such as argon or krypton. This spacing might be a vacuum, albeit more frequently, it is filled with gas to act as a barrier and reduce the heat transfer between the interior and exterior of a building. The two glass panes, together with the spacer, form a sealed unit known as an insulating glass unit (IGU).

Double glazing provides a higher degree of insulation, approximately twice the resistance to heat transfer, compared to single-glazed windows. This results in increased energy efficiency, reduced heating and cooling costs, and improved noise reduction. Additionally, double glazing can help prevent condensation and dampness in a building, especially on windows.

How Secondary Glazing Works

Secondary glazing functions by incorporating an additional barrier of insulation between the interior of a building and the outdoor elements. This supplementary windowpane serves to trap a layer of air between itself and the existing window. This trapped air improves the insulation performance of the existing window by minimizing the rate of heat transfer, reducing draft, and resulting in less energy required to heat or cool the space.

In addition to thermo-insulation properties, secondary glazing can also significantly reduce noise pollution. Under certain conditions, such as the thickness and type of the glass used and the gap between the primary and secondary panes, secondary glazing can reduce noise by up to 80%. This feature makes it particularly suitable for properties near busy roads, train lines, or airports.

How Double Glazing Works

Double glazing works to insulate a property by trapping air (or inert gas) between the two layers of glass panes. The air or gas trapped within the insulating glass unit acts as an effective thermal insulator due to its resistance to heat transfer. This reduces the amount of heat that can pass through the window, minimizing heat loss during winter months and heat gain during the summer.

Double glazing units often include a spacer bar of an insulating material separating the two panes, further improving the insulating performance. The spacer bar also contains desiccant, a moisture-absorbing substance, to prevent condensation within the sealed unit.

The type of gas used between the glass panes in double-glazed windows can also impact their insulation performance. Inert gases like argon, krypton, and xenon are better insulators compared to air, due to their lower thermal conductivity.

Overall, double glazing provides a wide range of benefits, such as improved thermal insulation, reduced energy consumption, increased security, and noise reduction. These features make it a popular choice for residential and commercial properties alike.

Comparing the Installation Process

When choosing between secondary glazing and double glazing for your windows, it’s important to consider the differences in their installation process. These differences include the actual steps involved in fitting them, the time and cost associated with the process, and the skills required for a successful and hassle-free installation.

Installing Secondary Glazing

Secondary glazing is the process of fitting a second pane of glass inside the existing window frame, parallel to the primary glazing. The aim is to provide better insulation, reduce noise and create a more energy-efficient home. The installation process for secondary glazing typically involves the following steps:

  1. Measure the window: The first step is to measure the interior dimensions of the existing window frame, including height and width, so that the secondary glazing can be custom-made to fit perfectly.
  2. Choose a supplementary glazing system: There are various types of secondary glazing systems to choose from, such as sliding, fixed, lift-out or hinged panels. Select the system that suits your needs and preferences best.
  3. Install the frame: The secondary frame, which will hold the additional glass pane, is fitted directly onto the interior window sill or window frame.
  4. Install the secondary pane: Place the secondary pane of glass into the frame, ensuring it is positioned securely.
  5. Seal the frame: Apply a suitable sealant around the edges of the frame to ensure there are no gaps, and the system is airtight. This helps in minimizing draughts and maximizing thermal and acoustic insulation.

Installing Double Glazing

Double glazing is the process of fitting two panes of glass within a single window frame, with a gap in between the panes. This gap traps air or gas, creating effective insulation against both thermal and acoustic factors. The installation process for double glazing is more complex than that of secondary glazing and usually involves the following steps:

  1. Remove old windows: The existing single-glazed windows need to be removed from the frames.
  2. Measure the frames: Accurate measurements of the existing frames are required to ensure the new double-glazed windows fit perfectly.
  3. Order the double-glazed windows: Once measurements are taken, custom-made double-glazed windows can be ordered to fit the existing frames.
  4. Install the new windows: After the new double-glazed windows are manufactured, they are installed into the existing frames.
  5. Seal the edges: Once the double-glazed windows are in place, any remaining gaps are sealed to ensure airtightness, and no air can pass through.

Time and Cost Involved

Secondary glazing is generally quicker and less expensive to install than primary glazing. This is because it doesn’t require major structural changes or the removal of the existing windows. Secondary glazing installations typically take one to two days, while double glazing installations can take up to a week or more, depending on the number of windows and the complexity of the job.

The cost of secondary glazing will usually be less due to the simplified installation procedure and the fact that less material is used. Double glazing can be more expensive, but it’s essential to weigh the long-term benefits, as double glazing can offer more significant energy savings over time.

Skills Required for Installation

Secondary glazing installation can often be completed by individuals with basic DIY skills, but it is recommended to use a professional installer for best results.

Double glazing, on the other hand, usually requires a specialist team with experience in installing such window systems. This is important not only for the appearance and performance of the windows but also for the warranty coverage, as improper installation can void any guarantees provided by the manufacturer.

Noise Reduction Mechanism in Secondary Glazing and Double Glazing

Noise pollution can be a significant concern in urban and suburban homes, causing disruptions to daily life, difficulty sleeping, and stress. To help reduce noise pollution from entering your home, two popular window options to consider are secondary glazing and double glazing. Both options work to reduce noise levels through different mechanisms, which will be discussed in this article to help you make an informed decision.

Noise Reduction in Secondary Glazing

Secondary glazing is the process of installing a second pane of glass within an existing window frame, creating an air gap between the two panes. This additional barrier works to dampen external noise by trapping and dispersing the sound energy before it enters the interior space.

One significant advantage of secondary glazing is that it can be retrofitted onto existing windows without the need for complete window replacement. This makes it an attractive choice for those living in older homes or buildings with single-glazed windows that do not meet modern noise reduction standards.

How does secondary glazing work to reduce noise? The key is the air gap between the two panes of glass. Sound waves lose energy as they travel through the air gap, resulting in a reduction of sound transmission into the interior space. Generally, the larger the air gap, the greater the noise reduction capability of the secondary glazing system.

Noise Reduction in Double Glazing

Double glazing consists of two panes of glass separated by a sealed spacer bar, creating an insulating air or gas-filled gap between them. The principle of noise reduction in double glazing is similar to that of secondary glazing: the air or gas layer helps dissipate sound energy, reducing the amount of noise that enters the interior space.

In addition to noise reduction, double glazing also provides excellent insulation against heat loss, helping to lower energy bills. However, unlike secondary glazing, double glazing typically requires the replacement of the entire window unit, potentially resulting in a more costly installation.

Determining Factors Influencing Noise Reduction

While both secondary glazing and double glazing work through similar principles to reduce noise levels, several factors can influence the effectiveness of each system.

Thickness of Glass

The thickness of the glass panes in both secondary glazing and double glazing systems can have a significant impact on noise reduction. Thicker glass absorbs more sound energy than thinner glass, providing better noise reduction capabilities. Using different thicknesses of glass in the primary and secondary panes can also reduce resonance between the panes, further improving sound insulation.

Air Gap

As mentioned earlier, the air gap between the panes of glass plays a crucial role in noise reduction. Generally, larger air gaps are more effective at reducing noise transmission, with diminishing returns beyond a certain point. In secondary glazing, this means the larger the gap between the existing window and secondary pane, the better. For double glazing, gas-filled gaps can provide additional sound insulation compared to air-filled gaps due to the different sound transmission properties of the gases used.


Finally, the effectiveness of noise reduction in secondary glazing and double glazing systems depends on the quality of the seals around the panes of glass. Poorly sealed systems may allow sound to bypass the air gap, reducing the overall noise reduction capabilities. Ensuring that your chosen glazing system has high-quality seals and professional installation can make a significant difference in achieving the desired level of noise reduction in your home.

Comparative Analysis of Noise Reduction Performance


Measuring Noise Reduction

Noise reduction is an essential aspect of building design, particularly in urban areas where the noise pollution level can be high. One effective method to block the noise from entering a building is by using glazing windows, especially secondary and double glazing. To measure and compare the noise reduction performance of these two types of glazing, it is crucial to conduct acoustic testing, as it can be the basis for evaluating which method provides better results.

Acoustic tests generally calculate the performance in terms of the Sound Reduction Index (SRI) or the noise reduction coefficient (NRC). These values indicate the amount of noise that is absorbed or blocked by the glazing system. An SRI range from 0 to 1 represents no noise reduction to complete noise reduction, respectively.

Effectiveness of Secondary Glazing for Noise Reduction

Secondary glazing is installed in addition to the existing primary glazing, creating an additional barrier between the interior and exterior of a building. It effectively reduces noise by increasing the mass of the window system, trapping air between the two glazing layers, and by slightly offsetting the two glass panes so that noise encounters dissimilar surfaces.

In terms of noise reduction, secondary glazing can typically offer an SRI of between 40 dB and 45 dB. This level of noise reduction can eliminate the majority of external noise caused by traffic, trains, and construction activities, making it a popular choice for retrofitting and preserving historical buildings. Besides, it is compatible with various glazing options, including laminated glass, toughened glass, and even acoustic glass.

Effectiveness of Double Glazing for Noise Reduction

Double glazing windows consist of two panes of glass with an air gap or an inert gas like argon or krypton between them. They are sealed together into a single unit, reducing both heat loss and noise transmission. The performance of double-glazed windows in terms of noise reduction is highly dependent on factors such as thickness, gap width, and the type of gas filling the space between the glasses.

Typically, double glazing can achieve an SRI of between 28 dB and 35 dB, which is lower than the noise reduction achieved by secondary glazing. However, double-glazed windows provide additional benefits like improved insulation, energy savings, and security.

Acoustic Test Results Comparison

Comparing the acoustic test results of secondary glazing and double glazing, it is evident that secondary glazing offers better noise reduction performance. The average SRI value for secondary glazing (40-45 dB) is higher than that of double glazing (28-35 dB). However, noise reduction is not the only factor to consider when choosing the appropriate glazing system. It is essential to weigh the pros and cons of each system and evaluate their suitability for specific settings.

Pros and Cons of Secondary Glazing and Double Glazing for Noise Reduction

Advantages of Secondary Glazing

Some of the primary advantages of secondary glazing include:
1. Superior noise reduction, as it consistently offers higher SRI values than double glazing.
2. Ideal for retaining the aesthetics of historical and listed buildings, where replacing windows may be undesirable or prohibited.
3. Easy to retrofit to existing window frames, making it a cost-effective solution.
4. Reduced condensation, as the additional glazing layer helps regulate indoor humidity.

Disadvantages of Secondary Glazing

The drawbacks of secondary glazing include:
1. Limited thermal insulation when compared to double glazing. This may lead to higher energy bills.
2. Reduced access to the original windows, particularly for maintenance and cleaning purposes.
3. Visual appearance may not be as seamless and modern as double glazing systems.

Advantages of Double Glazing

Double glazing has the following benefits:
1. Provides both noise reduction and thermal insulation, making it an energy-efficient solution.
2. Modern appearance, seamlessly blending with most architectural styles.
3. Increased security due to strong window framing materials and multi-point locking systems.
4. Requires less maintenance, as it typically involves a sealed unit.

Disadvantages of Double Glazing

Some of the disadvantages of double glazing include:
1. Generally lower SRI values than secondary glazing, leading to lesser noise reduction.
2. Can be more expensive to install, particularly in cases where existing windows need to be replaced.
3. Limited suitability for historic and listed buildings, as they may alter the aesthetics or be restricted by regulations.

Overall, both secondary and double glazing have their pros and cons when it comes to noise reduction. Secondary glazing is generally more effective at blocking sound than double glazing. However, double glazing offers better insulation and a sleeker appearance. The choice ultimately depends on the specific requirements of the building, budget limitations, and aesthetic preferences.

Other Benefits of Secondary Glazing and Double Glazing

Secondary glazing and double glazing provide several benefits, including improved insulation, energy efficiency, security, and condensation control. These advantages make them popular choices for residential and commercial properties.

Thermal Insulation

One of the primary benefits of secondary glazing and double glazing is their capacity to provide superior thermal insulation. Thermal insulation refers to the ability of a material to reduce heat transfer and keep the temperature constant within an area. In the case of windows, it means minimizing heat loss during cold weather and preventing excessive heat gain during hot weather, thus creating a more comfortable living or working environment.

Secondary glazing involves adding an extra pane of glass on the inner side of an existing window, creating an air gap between the two panes. This air gap serves as an insulating barrier, reducing heat transfer through the glass. Similarly, double glazing comprises two panes of glass, with an air or gas-filled gap in between. The insulation properties of double glazing are better than single glazing and can be further enhanced by using low-emissivity glass, which allows light to pass through while limiting the transfer of heat.

By providing better thermal insulation, both secondary glazing and double-glazing help maintain a more stable and comfortable indoor temperature. As a result, occupants can reduce their reliance on heating and cooling systems, leading to energy savings and reduced utility bills.

Energy Efficiency

Improving energy efficiency is a crucial aspect of sustainable building practices. Secondary and double-glazed windows contribute to energy efficiency by reducing the amount of heat transferred through the glass. This means less energy is required to maintain a comfortable interior temperature.

In turn, energy-efficient windows help homeowners and businesses cut down on energy consumption and save money on utility bills. Additionally, by reducing the demand on heating and cooling systems, secondary and double-glazed windows help lower greenhouse gas emissions, thus contributing to a more sustainable environment.

Choosing glass options like low-emissivity coatings and argon-filled gaps can enhance the energy efficiency of double-glazed windows. When planning a window upgrade or installation, it is essential to consider factors like the window’s U-value (the measure of heat transfer rates) and the solar heat gain coefficient. By selecting windows with low U-values and optimal solar heat gain coefficients for the local climate, owners can maximize the energy efficiency of their properties.

Security Features

Both secondary and double-glazed windows offer improved security compared to traditional single-glazed windows. The additional pane of glass in secondary glazing or the air gap in double glazing can make it more difficult for intruders to break into a building through its windows.

In addition to this basic security advantage, many secondary and double-glazing systems come with additional security features like multipoint locking systems and reinforced glass. These enhancements can deter would-be burglars and provide increased peace of mind for property owners.

Condensation Control

Condensation on windows can lead to a range of issues, including mold growth, reduced indoor air quality, and damage to window frames. Secondary and double-glazed windows can help control condensation in two ways:

  1. By reducing heat transfer, these windows help maintain a stable indoor temperature, making it less likely for moist air to condense on the window’s interior surface.
  2. Double-glazed windows typically have a warmer interior glass surface, further reducing the chance of condensation.

Overall, secondary and double-glazed windows offer several benefits beyond their primary energy-saving advantages. Thermal insulation, energy efficiency, security features, and condensation control are all additional reasons why property owners should consider investing in these window types.

Choosing the Right Option for Your Needs

When it comes to improving your home’s thermal efficiency, noise reduction, and overall comfort, two options stand out: secondary glazing and double glazing. Before making a decision, it’s crucial to take into consideration your specific requirements, budget constraints, and other factors. In this section, we will go through the essential aspects that need to be taken into account when comparing secondary and double glazing to help you choose the best option for your needs.

Assessing Your Noise Reduction Requirements

Noise reduction is an essential aspect for many homeowners, especially for those living in busy urban areas. Both secondary glazing and double glazing can significantly reduce outside noise, but their effectiveness may differ depending on your needs and circumstances.

Secondary glazing involves adding an extra pane of glass to your existing windows and creates an air gap between the two glass panes. This air gap helps to significantly reduce the transmission of sound waves because they are absorbed by the air, resulting in quieter living spaces. Secondary glazing tends to perform better when it comes to noise reduction compared to standard double glazing.

Double glazing, on the other hand, is the installation of two panes of glass separated by an air or gas-filled space. While double glazing offers some noise reduction properties, it’s primarily designed for better thermal insulation. For exceptional acoustic performance, consider opting for acoustic laminate glass or specialized noise-reducing double glazing options available in the market.

Considering Cost and Installation Factors

Cost and ease of installation are crucial when comparing secondary glazing and double glazing. Secondary glazing can be more affordable than double glazing because it involves adding an extra pane of glass to your existing windows, which means no structural alterations are needed, and labor costs are reduced. Additionally, secondary glazing can be a DIY project, further reducing the cost and allowing for a faster installation process.

On the other hand, double glazing usually requires replacing your windows entirely, which can be more expensive and lead to a longer installation time, since it involves more significant work and may require additional planning permissions or adherence to building regulations.

Comparing Other Benefits Between Secondary and Double Glazing

While both secondary and double glazing provide noise reduction and thermal insulation, each presents additional benefits:

  • Secondary glazing can be more discreet and less visually intrusive than double glazing. This is particularly beneficial for those living in listed buildings or conservation areas, where maintaining the original external appearance of the windows is crucial.
  • Double glazing offers better energy efficiency and insulation properties compared to secondary glazing. This is because the gap between the panes in double glazing can be filled with argon or krypton gas, which improves insulation. Consequently, double glazing can perform better in preventing heat loss and keeping your home warmer during colder months.
  • Double glazing can also improve your home’s security as it features more robust locking mechanisms and thicker, tougher glass panes.

Seeking Professional Advice

Before settling on either secondary or double glazing, it’s essential to seek professional advice from reputable companies or contractors specializing in window installations and glazing solutions. Discuss your specific requirements, budget constraints, and any additional factors that may affect your decision. Gathering multiple quotes and comparing the options presented by different professionals can help you make an informed decision based on your needs and preferences. Ultimately, choosing the right option for your home should be guided by a balance between cost, effectiveness, and your specific requirements.

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FAQs on Noise Reduction Comparison Between Secondary Glazing and Double Glazing

1. How effective is secondary glazing compared to double glazing at reducing noise?

Secondary glazing reduces noise by up to 45 dB, while double glazing provides a reduction of up to 34 dB. This difference makes secondary glazing approximately 25% more effective at blocking noise from entering a property compared to double glazing.

2. What is the difference in cost between secondary glazing and double glazing?

Secondary glazing is generally less expensive compared to double glazing, as the former requires less material and labor. The cost of installing secondary glazing can be about 50% of the cost of double glazing, depending on the quality and size of the project.

3. Can secondary glazing and double glazing be combined for additional noise reduction?

Yes, combining secondary glazing with double glazing can provide additional noise reduction benefits. This combination can offer up to 50 dB of noise reduction, greatly improving the sound insulation in a property compared to using either system alone.

4. What are some disadvantages of secondary glazing in comparison to double glazing when considering noise reduction?

One disadvantage compared to double glazing is that secondary glazing is not as effective at reducing heat loss or improving energy efficiency. Double glazing provides superior thermal insulation due to its sealed unit of two panes with gas in between, making it more energy-efficient.

5. How does the installation process of secondary glazing compare to double glazing in terms of complexity and time?

Secondary glazing installation involves attaching an additional pane to existing windows, making it less invasive and faster than installing double glazing. Double glazing often requires complete window frame replacement, which can be more time-consuming and may involve additional property modifications.


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