The Ultimate Guide to Double Glazed Windows: Energy Efficiency, Benefits & Installation
Double glazed windows have become a staple feature in modern homes and commercial buildings due to their ability to enhance energy efficiency, reduce noise pollution, and increase property value. Whether you are renovating, building a new home, or upgrading your existing windows, understanding the ins and outs of double glazing is crucial.
In this comprehensive guide, we’ll explore everything you need to know about double glazed windows — from their construction and benefits to installation considerations and maintenance tips.
What Are Double Glazed Windows?
Double glazed windows, also known as insulated glass units (IGUs), consist of two glass panes separated by a space — usually filled with air or an inert gas like argon. The sealed gap acts as an insulating barrier that improves thermal performance and reduces the transfer of heat and sound.
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Structure of a Double Glazed Window:
- Two Glass Panes: Usually 4-6mm thick each.
- Spacer Bar: Maintains uniform distance between panes.
- Sealed Gap: Filled with dry air or gas.
- Desiccant: Inside the spacer bar to absorb moisture.
- Sealant: Ensures the entire unit is airtight.
Key Benefits of Double Glazed Windows
1. Energy Efficiency
Double glazing significantly reduces heat transfer. In the winter, it traps warm air inside; in summer, it prevents external heat from entering. This reduces reliance on heating and cooling systems, cutting energy bills dramatically.
2. Noise Reduction
The insulating layer of gas and glass acts as a buffer against external noise — ideal for homes near busy roads, airports, or urban areas.
3. Enhanced Security
Double glazed windows are tougher to break than single-glazed units, offering improved resistance to forced entry. They can also accommodate laminated or toughened glass for extra security.
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4. Condensation Control
The thermal insulation reduces interior surface condensation, minimising the risk of mould and water damage around your window frames.
5. Increased Property Value
Installing double glazing improves your home’s Energy Performance Certificate (EPC) rating, making it more appealing to buyers and potentially increasing resale value.
Types of Double Glazed Windows
1. uPVC Double Glazed Windows
- Most popular and cost-effective.
- Low maintenance, durable, and available in various colours.
2. Aluminium Double Glazed Windows
- Sleek and modern appearance.
- Strong and corrosion-resistant.
3. Timber Double Glazed Windows
- Traditional and elegant.
- Environmentally friendly but requires regular maintenance.
4. Composite Double Glazed Windows
- A blend of materials like timber on the inside and aluminium on the outside.
- Combines aesthetic appeal with weather resistance.
Gas Fills: Argon vs Krypton vs Xenon
The gas between panes enhances insulation:
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- Argon: Most common, cost-effective, and 30% less conductive than air.
- Krypton: More efficient than argon but more expensive.
- Xenon: Premium option with superior insulation properties.
Frame Options
Window performance also depends on frame material:
- uPVC: Low-cost and energy-efficient.
- Wood: Great insulation but needs upkeep.
- Aluminium: Durable and recyclable.
- Fibreglass: Long-lasting and very energy efficient.
Window Styles Available
- Casement Windows: Hinged at the sides, open outward.
- Sash Windows: Traditional, with vertical or horizontal sliding panels.
- Tilt and Turn Windows: Dual-function — tilts inward or swings open.
- Bay & Bow Windows: Extends outward, ideal for extra space and light.
Installation Process
Proper installation is essential for performance. A professional installer will:
- Remove existing window frames.
- Prepare the window opening.
- Fit the new double glazed unit.
- Seal the window for airtight protection.
- Test for smooth operation and energy efficiency.
DIY vs Professional Installation
While some opt for DIY, it’s best to hire certified installers. They ensure the window meets building regulations and offer guarantees on work.
Double Glazing and Energy Ratings
In the UK, windows are rated from A++ to E under the BFRC (British Fenestration Rating Council) system. Look for:
- A-rated windows: Best thermal performance.
- U-values: Lower U-values indicate better insulation (1.6 W/m²K or lower is ideal).
Maintenance Tips
Double glazed windows are low-maintenance, but here’s how to prolong their life:
- Clean glass with mild detergent: Avoid abrasive materials.
- Check seals regularly: Ensure airtight fit.
- Inspect for condensation: Persistent fogging could indicate seal failure.
- Lubricate hinges and locks: For smooth operation.
Cost of Double Glazed Windows
Prices vary depending on size, style, and material:
- uPVC Casement Window: £250 – £500
- Timber Sash Window: £800 – £1,500
- Aluminium Window: £600 – £1,000
Installation costs can range between £150 – £400 per window. While upfront costs may seem high, energy savings and increased home value make it a smart investment.
Common Problems and Solutions
| Problem | Cause | Solution |
|---|---|---|
| Condensation between panes | Seal failure | Replace sealed unit |
| Draughts | Faulty installation | Re-seal or refit |
| Fogging | Moisture ingress | Check and fix seal |
| Difficulty opening | Misaligned frame | Adjust hinges or replace |
Double Glazing vs Triple Glazing
| Feature | Double Glazing | Triple Glazing |
|---|---|---|
| Layers of glass | 2 | 3 |
| Thermal performance | Excellent | Superior |
| Cost | Lower | Higher |
| Noise reduction | Good | Better |
| Weight | Lighter | Heavier |
Triple glazing is ideal for extreme climates or maximum soundproofing, but for most UK homes, double glazing provides excellent performance and value.
Environmental Impact
Double glazed windows help reduce carbon footprints:
- Lower energy use = fewer emissions.
- Long lifespan = less waste.
- Many materials (like aluminium and glass) are recyclable.
Choosing eco-friendly manufacturers and certified products further supports sustainable living.
Choosing the Right Supplier
When selecting a double glazing company, consider:
- Certifications: FENSA or CERTASS approved.
- Guarantees: At least 10 years is standard.
- Reviews: Check Trustpilot, Google, or local forums.
- Quotes: Get at least 3 to compare.
Final Thoughts
Double glazed windows are a smart, sustainable upgrade for any property. From energy efficiency and security to comfort and style, the benefits are clear. With the right choice of frame, glazing type, and a qualified installer, you can enjoy a warmer, quieter, and more cost-effective home.
Whether you’re replacing old windows or installing new ones, investing in double glazed units is a decision that pays for itself in comfort, savings, and property value.
