James Elston

James Elston

Published March 25, 2025

Last Updated on March 25, 2025

Old Double Glazing vs New Double Glazing

When it comes to upgrading your home’s windows, understanding the differences between old double glazing vs new is essential. Whether you’re a UK homeowner, landlord, or managing a commercial property, knowing how modern double glazing outperforms older installations can help you make an informed decision.

In this guide, we’ll compare old vs new double glazing in terms of insulation, security, energy efficiency, maintenance, costs, and more.

Old vs New Double Glazing: Key Differences

1. Insulation & Energy Efficiency

  • Old double glazing may have lost its argon gas, reducing insulation and leading to higher energy bills.
  • New double glazing is designed with warm-edge spacer technology, Low-E coatings, and better seals, reducing heat loss and keeping your home warmer.

Modern A-rated double glazing can cut energy bills by up to 30% compared to old units.

2. Draughts & Ventilation

  • Older windows often suffer from draughts due to seal failure and gaps forming over time.
  • Newer double glazing is airtight, reducing cold spots while incorporating trickle vents for controlled airflow.

3. Security Features

  • Older double glazing may have weak locks and thinner glass, making it easier for intruders to break in.
  • New double glazing includes multi-point locking systems, laminated glass, and reinforced uPVC or aluminium frames for added security.

4. Noise Reduction

  • Old windows lose their soundproofing ability over time.
  • Newer models use acoustic laminated glass to block up to 40dB of noise, ideal for homes near busy roads or airports.

5. Light & Aesthetic Appeal

  • Older double glazing can develop a cloudy appearance due to condensation inside the panes.
  • New double glazing provides clearer, more natural light with advanced coatings that reduce glare while maintaining brightness.

6. Maintenance & Longevity

  • Older double glazing requires more maintenance, as the seals break down, and frames deteriorate.
  • Newer units are designed to last 25+ years with low-maintenance materials like uPVC and self-cleaning glass options.

7. Cost & Installation

Upgrading to new double glazing can be a long-term investment that boosts your property value. Below is a cost comparison:

Window TypeCost per Window (Supply & Install)Lifespan
Old Double Glazing (Replacement Glass Only)£150 – £30010-15 years
New A-Rated uPVC Double Glazing£400 – £60025+ years
New Aluminium Double Glazing£600 – £1,00030+ years
New Timber Double Glazing£1,000+40+ years

Installing new double glazing can increase your home’s value by up to 10% and improve its EPC rating. Check out our double glazing cost guide for a detailed breakdown of what you can expect to pay. 

Is It Worth Replacing Old Double Glazing?

If your energy bills are rising, windows feel draughty, or you notice condensation inside the glass, it’s time to upgrade. Modern double glazing will make your home warmer, quieter, and more secure while boosting property value.

If you need to replace your windows, check out our 2025 guide on new window costs to better understand the prices for different window types.

Comparing Double Glazing to Other Window Options

Double glazing is a popular choice for energy efficiency and comfort, but other glazing options may suit different needs. Here’s how they compare:

  • Secondary glazing adds an extra pane inside existing windows, improving insulation and noise reduction. While it’s a good alternative for listed buildings, it doesn’t match the efficiency of a fully sealed double-glazed unit. Check out our in-depth comparison of secondary glazing vs. double glazing to learn more.
  • Single glazing offers minimal insulation, leading to heat loss and higher energy bills. At Eco Happy, we’re often asked about the differences between single and double glazing, so we’ve put together a comprehensive guide to explain it all.
  • Triple glazing adds a third pane for extra insulation and noise reduction. While beneficial in colder climates, the added cost may not be justified in milder regions. Take a look at our guide for a detailed comparison of triple and double glazing.
  • Acoustic glass is specially designed to block noise more effectively than standard double glazing. It’s ideal for homes near busy roads or airports where soundproofing is a priority. Want to understand the difference between acoustic glass and double glazing to find the best option for your home? Check out our guide.
  • Low-E (low-emissivity) glass has a special coating that reflects heat, enhancing energy efficiency. Many modern double-glazed units incorporate Low-E glass for better thermal performance. We’ve put together a simple, easy-to-follow guide comparing Low-E glass and double glazing.

Each option has its advantages, depending on your priorities—whether it’s insulation, noise reduction, or preserving existing windows.

Are You Considering Upgrading Your Windows?

Upgrading your windows is a great way to improve your home’s energy efficiency, security, and overall comfort. Whether you’re looking to reduce noise, lower energy bills, or enhance your property’s curb appeal, choosing the right windows is key.

Before making a decision, it’s important to compare different options, materials, and costs. Our expert team can help you find the best solution for your home. Get a free window replacement quote today and take the first step toward a warmer, quieter, and more efficient home.

James Elston

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.

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