Secondary Glazing - Thermal Insulation

Energy efficient insulation for windows

This page gives you an explanation of all aspects of secondary glazing for thermal insulation, energy efficiency & energy saving and how we can help you to save energy at home by insulating your windows.

For thermal insulation, the Energy Efficiency range of secondary glazing is the best choice as it is:

  •  Designed for maximum energy efficiency
  • Very effective against heat loss through the windows
  • Extremely discreet for glass & glazing insulation
  • The best all-round single glazing insulation available
  • Environmentally friendly and saves energy
  • Much more economical than replacement double glazing 

Correctly specified and installed, our secondary glazing can achieve thermal insulation for windows with an equal to or better rating than current Building Regulations. 

It is also the product of choice for Traditional Houses, Flats, Listed Buildings and Conservation Areas.

Thermal Insulation 1

Important Considerations for Thermal Efficiency

Thermal efficiency insulation is expressed as the U value - the smaller the U value, the better the window insulation.

Thermal Insulation 2

Optimum Performance

Assuming an average single glazed wooden primary window and secondary glazing with 6mm Low E Pilkington K thermal insulating glass.

  • We can achieve thermally efficient U values for windows of 1.5W/m²K
  • The standard for residential modern replacement windows is 1.6W/m²K

Thermal efficiency can be expressed as a WER rating.

Secondary glazing with 6mm energy saving (low E) “K” glass, fitted over a typical traditional timber window, will achieve a WER Rating Scale of:

  • B or C Rated

By fitting the secondary glazing with double glazed low E “K” glass we can achieve a WER Rating Scale of:

  • A Rated

Dependent upon the cavity achieved and the glazing thickness (usually 4mm) of the primary window.

Thermal Insulation 3

Benefits of Secondary Glazing: 

  • Cheaper than replacements for insulating windows & doors
  • No more draughts or cold spots
  • Truly energy efficient windows
  • Significant reduction in noise from outside
  • Quick, clean house insulation
  • Minimal or no redecorating required
  • Maximum heat insulation for reduced bills 
  • The “greener” solution – materials used produce far less CO2 than PVCu replacements
  • Extends the life of your existing windows & keeps them out of land fill sites
  • Improved security
  • Keeps the original appearance & protects the value of your home
  • Not usually affected by Conservation Area orListedBuildingregulations
  • Improved Energy Performance Certificate
  • Reduced carbon footprint

Please contact our Glazing Department for more information.