Windows and glazing

Around 10% of your home's heat can escape through your windows. Energy-efficient glazing can help to keep your home warmer, quieter and reduce your energy bills.

Why change your glazing?

Energy efficient windows, when fitted properly, could save you money on your home heating and lighting bills and reduce your carbon emissions. They can also help to shield your home from outside noise and increase comfort and warmth by reducing heat loss, draughts, cold spots and condensation.

How much could you save?

The savings from energy-efficient glazing will vary from one property to another depending on the windows, their size and the material they are made from. However, once installed, double glazing should last for at least 20 years.

  • Annual saving of £165 on average;
  • Annual CO2 saving of 680kg.

These amounts, estimated by the Energy Saving Trust, are based on an average three-bedroom home.

How energy efficient glazing works

Heat transfer through glazing accounts for around two-thirds of the energy lost from a standard window. Double-glazed windows have two sheets of glass with a gap of around 16mm between them which creates an insulating barrier to keep the heat in. Triple-glazed windows work in the same way but have three sheets of glass, although triple glazing is not always more efficient than double glazing. The energy efficiency can also vary depending on the frame material and style, how well they stop heat from passing through the window, how much sunlight passes through the glass and how much air can leak in or out of the window.

A home energy assessor will check your existing glazing to see if replacement would have a significant impact on the energy efficiency of your home. This will take into account any complications, such as whether you live in a period property, conservation area or a listed building. When deciding on the recommended options, the assessor will look at the energy rating of the glass, the gap between the sheets of glass and the pane spacers which are set around the edges to keep the two apart.