1. How energy efficient are the windows?

When deciding on replacement double glazing, you can find out about energy efficiency by keeping an eye out for the Energy Saving Trust logo and British Fenestration Rating Council (BFRC) rating. The higher the rating of energy, more energy efficient it is. The EST supports rated B and above windows. While there is currently no requirement for manufacturers to display labels on their products; by choosing a highly-rated window, you know you are going to buy the most efficient.

2. How many layers are best?

Double glazed windows contain two glass layers with a gap of around 16mm. Triple glazing is also available, consisting of three glass layers.

3. Which kind of glass is better?

Low-emissivity (Low-E) glass is the best for energy efficiency. It often has a subtle layer of metal oxide, usually at one end of the internal panel – next to the gap. This allows sunlight and heat inside but cuts the amount of heat that can get out again.

4. What is between panels?

Highly efficient windows often use gas like xenon, argon or krypton in the gap, or a vacuum between the two glass sheets.

5. What separates the panels?

All windows have double glass spacer panels arranged around the inside edge to keep the two glass panels apart. For a more efficient window, look for a spacer panel containing little or no metal – often known as a ‘warm edge’ spacer. For more information on Double Glazing Swindon, visit a site like Kingfisher Windows, a supplier of Double Glazing Swindon.

6. Will the frame suit your home?

The frame you ultimately decide on will depend on your property and personal taste. There is sure to be a window frame material available in each energy rating and that will match your home.

uPVC frames are the most common type. They last longer and can be recycled.

Wooden frames can have a lower environmental impact but do require care. They are often used in conservation areas where native timber framed windows are found.

Aluminium or steel frames are thin and durable. They too can be recycled.

Composite frames have a wooden frame inside coated with aluminium or plastic. This reduces the need for maintenance.

7. Do I need ventilation?

Due to the fact that replacement double-glazing is more airtight than original glass frames, condensation can build up in your home because the ventilation is reduced.

If there is not enough background ventilation in the room, some replacement windows will have trickle vents incorporated into frames that let in a small amount of controlled ventilation.

Condensation can occasionally occur on the outside of the new low-e glass. This is because the low-e glass reflects heat back into the house and as a result the remnants of the cold outer panel and condensation can build up in the cold weather – but it’s not something to worry about.