James Elston
Published March 24, 2025
Last Updated on March 25, 2025
Secondary Glazing vs Double Glazing: Which Is Better?
When it comes to improving energy efficiency, reducing noise, and enhancing security, UK homeowners and landlords often compare secondary glazing vs double glazing. But which is the right choice for your property?
This comprehensive guide explores the differences, benefits, costs, and installation processes of secondary glazing and double glazing, helping you make an informed decision.
Contents
- 1 Secondary Glazing vs Double Glazing: Which Is Better?
- 1.1 Secondary Glazing vs Double Glazing: A Quick Comparison
- 1.2 What is Secondary Glazing?
- 1.3 What is Double Glazing?
- 1.4 Window Styles Suitable for Secondary & Double Glazing
- 1.5 Energy Efficiency & Insulation
- 1.6 Cost & Installation: Secondary vs Double Glazing
- 1.7 Which One Should You Choose?
- 1.8 Comparing Different Glazing Options for Your Home
- 1.9 Time for a Window Upgrade?
Secondary Glazing vs Double Glazing: A Quick Comparison
| Feature | Secondary Glazing | Double Glazing |
|---|---|---|
| Energy Efficiency | Moderate improvement | High insulation, better heat retention |
| Noise Reduction | Excellent (reduces up to 80% of noise) | Good (reduces up to 60% of noise) |
| Security | Moderate (existing window remains) | High (toughened glass & locking mechanisms) |
| Draught Prevention | Reduces draughts but depends on fit | Sealed unit provides full draught-proofing |
| Ventilation | Windows can still be opened | Depends on window style |
| Light Transmission | No impact on natural light | May slightly reduce light due to frame thickness |
| Maintenance | Low maintenance, easy to clean | Regular cleaning and maintenance required |
| Installation Process | Quick and non-intrusive | Full window replacement required |
| Cost | Lower cost | Higher cost but long-term savings |
| Best for | Listed buildings, period homes, rental properties | Modern homes, new builds, full renovations |
What is Secondary Glazing?
Secondary glazing involves installing a separate pane of glass on the inside of your existing single-glazed windows. This creates an additional layer of insulation without altering the external appearance of your property.
Key Features of Secondary Glazing
Pros and Cons Of Secondary Glazing
| Pros |
| Cons |
What is Double Glazing?
Double glazing consists of two panes of glass separated by a layer of air or inert gas, typically argon or krypton, within a sealed unit. This advanced insulation method significantly improves thermal efficiency and security. For detailed insights into how double glazing works, read our guide.
Key Features of Double Glazing
Pros and Cons Of Double Glazing
| Pros |
| Cons |
Take a look at our guide on double glazing costs to get an idea of what you can expect to pay.
Window Styles Suitable for Secondary & Double Glazing
When deciding between secondary glazing and double glazing, it’s essential to consider the style of your existing windows. Some window types are more compatible with one option than the other, particularly in period properties, modern homes, and commercial buildings.
Below is a breakdown of how different window styles work with both glazing types.
| Window Type | Secondary Glazing | Double Glazing |
|---|---|---|
| Sash Windows | Ideal for listed buildings and heritage homes | Modern double-glazed sash units available |
| Casement Windows | Works well, minimal visual impact | Most common double-glazing style |
| Bay Windows | Can be secondary glazed to maintain character | Fully upgradeable with double glazing |
| Tilt & Turn Windows | Not ideal due to opening mechanism | Designed for double glazing |
Sash Windows
Sash windows are a classic feature of Victorian and Georgian homes, making them a popular choice for secondary glazing. This allows homeowners to enhance insulation while preserving the traditional aesthetic. However, modern double-glazed sash windows offer a balance between efficiency and heritage style.
If you’d like to upgrade your home with sash windows, check out our sash window costs guide to get a clear idea of what you can expect to pay.
Casement Windows
Casement windows are one of the most versatile window styles, commonly found in both traditional and contemporary homes. They work well with both secondary and double glazing. Check out our casement window costs guide if you’re considering these windows for your home.
Bay Windows
Bay windows add character and space to a home but can be a source of heat loss and draughts. Secondary glazing is a great solution for maintaining period features, while double glazing significantly improves insulation.
Read more on how much bay windows cost.
Tilt & Turn Windows
Tilt and turn windows are modern and functional, designed to work best with double glazing due to their dual opening mechanism. If you’re considering a window upgrade, check how much tilt and turn windows cost to compare installation prices.
If you’re comparing prices for different window types, our new window costs guide provides a detailed breakdown to help you plan your budget
Energy Efficiency & Insulation
Double glazing is more thermally efficient due to its sealed air gap, which reduces heat loss significantly. Secondary glazing improves insulation, but its efficiency depends on the existing window condition.
Security Comparison
- Double glazing provides superior security due to toughened glass and multi-point locking.
- Secondary glazing offers added protection but depends on the existing window.
Draught Prevention & Ventilation
- Double glazing eliminates draughts with its sealed design.
- Secondary glazing reduces draughts but relies on the existing window seal.
Light & Aesthetic Considerations
- Secondary glazing preserves the original look of period properties.
- Double glazing may slightly reduce light due to thicker frames, but modern slimline frames are available.
Cost & Installation: Secondary vs Double Glazing
| Window Type | Secondary Glazing Cost (Per Window) | Double Glazing Cost (Per Window) |
|---|---|---|
| Casement Window | £300 – £600 | £500 – £1,200 |
| Sash Window | £400 – £800 | £800 – £1,500 |
| Bay Window | £1,000 – £3,000 | £1,500 – £4,000 |
| Whole House (8-10 Windows) | £3,000 – £6,000 | £5,000 – £12,000 |
Installation Considerations:
- Secondary glazing is a quick, non-invasive installation process.
- Double glazing requires full window replacement, taking a few days to complete.
If you’re considering upgrading your home with new windows, visit our window replacement quote page to get competitive pricing on high-quality window installations.
Which One Should You Choose?
Choose Secondary Glazing If:
Choose Double Glazing If:
Comparing Different Glazing Options for Your Home
When upgrading your windows, it’s important to understand how different glazing options compare. Here’s a quick look at how double glazing stacks up against other types of glass to help you make the best decision for your home:
Time for a Window Upgrade?
Upgrading your windows is a smart investment that can boost your home’s energy efficiency, security, and overall comfort. Whether you’re looking to reduce heat loss, block out noise, or enhance your home’s appearance, choosing the right windows is key.
Not sure where to start? We make the process easy. Get a free window replacement quote today and find the perfect windows to suit your home and budget.
James Elston
Boiler Expert
James Elston is the top boiler replacement and heating expert at Eco Happy. He has over 20 years of experience in the industry, focusing on Gas Safe boiler installations and offering home-heating and energy-saving solutions to homeowners across the UK. From sourcing the most energy-efficient combi boiler to providing specialist heating advice, James ensures that Eco Happy maintains the highest standards and best customer service.