A guide to double glazing

If you’re looking to make your home more energy efficient, reduce the impact of external noise and improve security, double glazing is the perfect choice.

Our comprehensive guide to double glazing tells you all you need to know about this popular choice for windows and doors, including how it works and the many benefits. 

How does double glazing work?

Double glazing is an insulated window or door with two glass panes divided by air or gas. This dense compound is a poor conductor of heat so it insulates and maintains the internal house temperature, with the second pane of glass acting as a barrier to noise.  Around the pane is insulating plastic, preventing further heat loss.

What are the benefits of double glazing 

Reduced heat loss

Did you know that heat loss through single glazing is around twice as fast as double glazing? By installing double-glazed windows, you could reduce this heat loss considerably, meaning lower heating bills.

Reduced noise 

While it won’t block out all noise completely, double glazing can significantly reduce the noise you hear from outside.

Reduced energy bills 

Replacing older units will save energy and money on your bills. By installing A-rated double glazing such as ours in an entirely single-glazed semi-detached gas heated property, you could save hundreds of pounds a year and 335kg of carbon dioxide.

Reduced condensation

Double glazing reduces moisture from converting into liquid, so it controls condensation on your windows. This not only improves visibility, it also reduces the opportunity for bacterial mould to grow, which means a healthier living space.

Improved safety

Because of its toughness, double glazing adds a layer of defence to your windows. Include strong locks to further increase your home’s safety.

Adds value to your home 

Estate agents believe that double-glazed windows or secondary glazing makes a home more ‘sellable’, more attractive, and can add up to 10% onto its value.

What are the double glazing ratings?

There is an energy-rating scale from A++ to E that window manufacturers use to show the energy efficiency of their products. The rating is given after assessing the entire window including the frame and glass. The 2002 building regulations state that all replacement windows must be a minimum rating of C unless the property is a listed building or in a conservation area.

What is a double glazing U-value?

Windows that have an energy rating will have the window’s ‘u-value’ displayed on the energy label. This is the measure of how easily heat passes through a material, but it is not a complete measure of how efficient a window is. To comply with building regulations, windows should have a U value of 1.6 W/m2K and double-glazed windows are typically 1.4 W/m2K.

Should I replace all my windows at once? 

If you can afford it, we would advise that you replace all your windows at once. This will save you less time, stress and paperwork. It may also save you money on the total cost too!

Why is there condensation in between my double glazing?

Condensation on the inside pane of your window

This is a sign of too much humidity in the room, or little to no air circulation. Improve the circulation of air to reduce humidity and help to clear moisture, and keep your property at a constant and reasonably warm temperature 

Condensation on the outside window pane

A rare occurrence, which means the unit is performing well, so there isn’t anything wrong.

Condensation in the ‘air gap’ between the two glass panes

Double-glazed windows deteriorate over time and eventually the seal around the panes starts to degrade and crack, allowing condensation into the ‘air gap’. On older or poor quality units, the sealant may be low grade or become loose over time. Often, just the glass can be replaced, but you may need to have a new window. 

How do you know when your double glazing needs replacing?

The lifespan of double glazing is estimated to be between 20 and 35 years depending on the supplier, fitter and your location (exposed or open areas often provide more adverse and challenging conditions).

There are a few signs to look for when your double-glazed windows may need replacing. These include condensation, draughts, leaks and water coming in, or the windows being difficult to open, close, or lock. Also look out for a higher noise level, yellowing uPVC, cracking timber or visible damage particularly to the seals. 

Don’t worry – some of these problems can be repaired, contact us for more information.

Are there restrictions on double glazing?

Check with your local planning office before replacing your windows if any of the following apply:

You live in a conservation area.

You have an article 4 direction on your property, removing the right of permitted development.

You live in a listed building.

Can you double glaze existing windows? 

Yes you can! This is known as secondary glazing, where a second slimline window is inserted just inside your existing window – a subtle change that won’t affect your property’s aesthetic and still has many of the properties of double glazing. This is ideal if you are unable to install double glazing due to the restrictions above.

Double glazing from CR Windows 

At CR Windows, we have over 40 years’ experience of providing quality windows, doors and conservatories. Our A-rated windows are accredited by the British Fenestration Rating Council (BFRC) for their energy efficiency. We offer a wide range of styles and a 10 year guarantee on all products manufactured and installed by us.

If you have any additional questions about double glazing, we’d love to help. Get in touch to speak to our team. 

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