Installing replacement windows is a long-term investment that will provide a strong return from resale value to savings.
Energy-efficient replacement windows can have a big impact on appearance and maintenance costs, as well as savings on your fuel bills. We will guide you and help you choose the best window to meet your needs and budget, whether it’s standard or custom replacement windows.
A bay window can be a beautiful addition to your home, and they are made up of three or more windows. The sash window has been a feature of British housing for several centuries. Our uPVC version is specifically designed never to stick, rattle or need painting. Each sliding sash is counter-sprung to glide smoothly up and down and stay open in any position.
Energy-Efficient Windows
- Smaller energy bills.
- Smaller carbon footprint.
- More comfortable home: energy-efficient glazing reduces heat loss through windows and means fewer draughts and cold spots.
- Peace and quiet: as well as keeping the heat in, energy efficient-windows insulate your home against external noise.
- Reduced condensation: energy-efficient glazing reduces condensation build-up on the inside of windows.
The costs and savings for energy-efficient glazing will be different for each home and each window, depending on its size, material and the installer you choose. Double glazing should last for 20 years or more.
How energy-efficient glazing works
Double-glazed windows have 2 sheets of glass with a gap of 20mm in between and triple glazed have 3 sheets of glass with a gap of 8mm on either side of the centre sheet of glass, to create an insulating barrier that keeps heat in. This is always filled with Argon gas and has warm edge spacers unless stated you didn¹t want A-rated windows. Triple-glazed windows have three sheets of glass. To choose the most energy-efficient window look for the BFRC rating.
Energy-efficient windows come in a range of frame materials and styles. Performance criteria vary according to the following:
- How much sunlight travels through the glass.
- How little air can leak in or out around the window.
What to look for
Glass
The most energy-efficient type for double glazing is Planitherm glass with a soft coat applied for an A-rated window or low emissivity (Low-E) glass. This often has an invisible coating of metal oxide, normally on one of the internal panes. This lets in light and heat but cuts the amount of heat that can get out.
Gaps between the glass
Very efficient windows might use gases such as argon, xenon or krypton in the gap between the sheets of glass.
Pane spacers
These are set around the inside edges to keep the 2 or 3 panes of glass apart this is what is called a warm edge spacer. For maximum efficiency, look for pane spacers containing little or no metal often known as Œwarm edge¹ spacers.
Frame materials
For all frame materials, there are windows available in all energy ratings.
- uPVC frames last a long time and may be recycled.
- Wooden frames can have a lower environmental impact but require maintenance. They are often used in conservation areas where the original windows had timber frames.
- Aluminium or steel frames are slim and long-lasting and may be recycled.
- Composite frames have an inner foam filled insulation covered with fibreglass. This reduces the need for maintenance and keeps the frame weatherproof.
Energy rating
Some window manufacturers show the energy efficiency of their products using an energy-rating scale from A to G. The whole window (the frame and the glass) is assessed on its efficiency at retaining heat. The scheme is run by the British Fenestration Rating Council (BFRC). Visit BFRC for more information.
Ventilation
Replacement windows will be more airtight than your original frames, so condensation may build up in your house due to the reduced ventilation. If your house does not have much background ventilation, look for replacement windows with trickle vents incorporated into the frame to let in a controlled amount of ventilation.
If you start to see condensation building up around your windows, there may be a damp problem in your home. As a general rule, dampness occurs when there is inadequate ventilation, inadequate heating, inadequate insulation or a combination of these. If you start to notice condensation in between the panes of glass in your double-glazing units then it is likely that the seal is broken, and the unit will need to be replaced.
Conservation areas
These areas are of special architectural or historic interest, meaning that any work you carry out on your home must preserve or enhance the character of the area. This does not necessarily mean you cannot replace your windows, but might mean you will need to get windows that complement the character of the building and area. Double glazing can be made to look like your building’s original windows, but for any changes, you do need to contact your local council¹s conservation officer for guidance.
Windows in period properties
If you live in a conservation area or a listed building there may be restrictions on what you can do to your windows. There are several non-intrusive window insulation options available for historic homes such as heavy-lined curtains, shutters, secondary glazing and sealed blinds. However, each historic building is considered individually so check with your local council to see what options are available to you.
Listed buildings
Listed buildings have tight controls on what you can change on the outside and sometimes the inside as well, depending on their grading. Old sash windows in historic properties can be protected not only for their appearance but also for the materials and methods used to make them. But secondary glazing can be a non-intrusive way of insulating historic windows from the inside and may be granted permission.
There are other ways to make historic buildings more energy efficient but you will need to consult and apply for permission from, your local planning authority.
Visit Historic Scotland and English Heritage for ways to make a historic home more energy efficient.
Sash windows
Sash window units are common features of period properties and can be a design feature. They consist of two vertically sliding frames but are often badly fitting and made of single-pane glass so have poor insulating properties.
If you want to insulate your sash windows there are several alternatives to conventional double glazing. If you want to keep the design and look of the sash windows, there are units available that are in keeping with the original design; these are fitted and sealed to prevent draughts and incorporate double glazing to reduce heat loss. The frames don¹t need to be plastic but can be metal or wood with an insulated core.
An increasing number of double-glazing companies offer double-glazing in period properties. Replacing sash windows can be expensive, so good-quality secondary glazing may be worth considering.
