Cozy home interior

Thermal Secondary Glazing

Cut heat loss through your windows by up to 64%. Our thermal secondary glazing solutions keep your home warmer in winter, reduce energy bills, and improve your property's EPC rating.

Benefits of Thermal Secondary Glazing

64% Heat Reduction

Dramatically reduce heat loss through single-glazed windows.

Lower Energy Bills

Significant savings on heating costs, especially with rising energy prices.

Reduced Carbon

Lower your home's environmental impact with improved efficiency.

Improved EPC

Boost your property's Energy Performance Certificate rating.

Understanding Thermal Performance

U-values measure how well a window prevents heat loss. Lower is better.

Window Type
U-Value (W/m²K)
Heat Loss
Single Glazing
5.0
Very High
Standard Double Glazing
2.8
Moderate
Modern Double Glazing
1.6
Low
Single + Secondary Glazing
1.8
Low

Adding secondary glazing to single-glazed windows achieves thermal performance comparable to modern double glazing.

How Thermal Secondary Glazing Works

Heat escapes through windows in two main ways: conduction through the glass itself, and convection through air movement. Single-glazed windows are particularly poor at preventing both types of heat loss.

Secondary glazing creates a substantial air gap between your existing window and the new internal panel. This trapped air acts as an insulating layer, dramatically reducing heat transfer. Our comprehensive sealing also eliminates draughts — a common problem with older sash windows.

The result is a warmer, more comfortable home with significantly lower heating bills. Many of our customers report that rooms that were previously cold and draughty become comfortable living spaces after secondary glazing is installed.

EPC Improvements

Energy Performance Certificates (EPCs) are increasingly important for property owners. Rental properties must meet minimum EPC standards, and buyers are increasingly focused on energy efficiency. Secondary glazing can improve your EPC rating by improving window thermal performance — often a significant factor in the overall assessment.

Reduce heat loss by up to 64%
Eliminate draughts from old windows
Warmer, more comfortable rooms
Lower heating bills
Improved EPC rating
Condensation reduction
No alterations to original windows
10-year guarantee on all work

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No obligation. No pressure. Just honest advice from London's secondary glazing specialists.

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