Triple Glazing vs Double Glazing -- What's worth it?

Is Triple Glazing Worth It for Roof Windows? Here’s the Pros and Cons

When it comes to roof windows, choosing the right glazing is just as important as the window placement or design. One of the most frequently asked questions by homeowners and architects alike is: "Is triple glazing worth it?" With energy efficiency and comfort top of mind, it's worth exploring the benefits and drawbacks of triple-glazed roof windows before you commit.

In this post, we break down the pros and cons of triple glazing in roof windows to help you make an informed decision.

What is Triple Glazing?

Triple glazing consists of three panes of glass with two insulating air or gas-filled gaps (usually argon or krypton) in between. Compared to double glazing, it offers an extra layer of thermal protection and can significantly reduce heat loss.

When applied to roof windows, triple glazing enhances performance even further — but is it always necessary?

The Pros of Triple-Glazed Roof Windows

1. Superior Thermal Insulation

Triple glazing offers excellent U-values (a measure of heat loss). Roof windows are especially vulnerable to heat escaping because warm air rises. The extra pane significantly improves insulation, helping you retain more heat during winter and keep things cooler in summer.

Ideal for: Passive homes, cold climates, and energy-conscious renovations.

2. Reduced Energy Bills

Over time, better insulation means less heating in winter and less cooling in summer. If you're installing multiple roof windows or upgrading an older property, the energy savings could be noticeable.

3. Improved Sound Insulation

If you live in a noisy area — near roads, railways, or flight paths — triple glazing can reduce outside noise, giving you a more peaceful interior. This is particularly beneficial in loft conversions or upper-level rooms under the roof.

4. Increased Comfort

Triple glazing helps eliminate cold spots and drafts often found under roof windows. You’ll experience a more even room temperature year-round, which enhances comfort and may boost the value of your home.

The Cons of Triple-Glazed Roof Windows

1. Higher Cost

Triple glazing is more expensive than double glazing — often 10–30% more. When installing several windows or sticking to a tight budget, the price difference can add up quickly.

Consider: Whether your home’s insulation and wall/window setup justify the upgrade.

2. Heavier Frames

Triple-glazed units are heavier, requiring stronger window frames and potentially more support in the roof structure. This could increase labour costs or complicate installations in older buildings.

3. Diminishing Returns in Mild Climates

In many parts of the UK or similar temperate regions, the energy efficiency gains may be minimal compared to modern double glazing with a low-E coating. For some homes, well-installed double glazing is “efficient enough.”

4. Reduced Solar Gain

Ironically, triple glazing may slightly reduce natural solar heat gain — the warming effect of sunlight entering your home. In cooler months, this could be a downside for homeowners hoping to passively warm their interiors.

So, Is Triple Glazing Worth It for Roof Windows?

Go for Triple Glazing if:

• You live in a colder region or exposed site.
  
  
• You want to future-proof your home’s insulation.
  
  
• Soundproofing is a priority.
  
  

• You’re building or renovating to Passivhaus standards.
  
  

Stick to Double Glazing if:

• Your home is in a mild climate.
  
  
• Budget is tight or you're working with existing roof structures.
  
  

• You want to maximize solar gain in winter.