The UK has some of the least energy efficient homes in Europe. A typical home loses 10-20% of their heat through windows and external doors. Installing energy efficient glazing and high thermal performance doors will reduce heat loss, to keep your home warmer and cut heating bills. Properly fitted double glazing can also help significantly reduce external noise and decrease condensation.
Consider your home’s overall insulation for maximum efficiency
Before investing in energy efficient glazing or high thermal performance doors, it’s worth checking whether you can also install additional energy saving options. A great place to start is the overall insulation of your home. On average 60% of heat is lost through the walls and loft combined. It therefore makes sense to insulate these areas, in combination with replacing old or single glazed windows or doors.
Choosing energy efficient doors & windows
If you’re concerned with your carbon footprint, as well as just saving money on heating your home, it’s worth taking some time to select the right products, as not all energy-efficient doors and windows are truly ‘green’. The best option is to select CFC-free doors and windows that are made with calcium zinc-based compounds. These tend to be less harmful to the environment, but will still meet the necessary regulations and will last for years.
At Newview sustainability is key to how we operate. We look to minimise the carbon footprint created through the whole supply chain, including the manufacturing and shipping of the windows and doors we fit, as well as ensuring as much of the materials we remove are recycled responsibly.
Where possible we will also look to use options that reduce the ‘product miles’ as much as possible, cutting down on fuel use and time on the road. This also applies to our fitting teams as we try to minimise the mileage travelled for each job by careful route planning and monitoring our vehicles mileage. This all goes to protecting the environment while saving you money at the same time.
How do energy efficient windows work?
There are three key factors that go towards increasing the performance of energy efficient glazing:
- How much light and heat are let in
- How much heat can escape
- If the glazing unit fits snugly with no air leaks.
The most energy efficient windows tend to be double glazed , which means they have two sheets of glass with a gap between them, often filled with an inactive gas such as argon. The gap creates an insulating barrier to slow down the rate at which heat escapes, and the bigger the gap between the panes (usually 16mm wide), the greater the insulation.
It’s possible to fit triple-glazed windows which have three sheets of glass and two insulating gaps. There is some debate as to whether triple glazing is better than double glazing – in deciding what’s right for your home you will also need to consider what the windows are filled with and the quality of the frames. The rough and ready method of comparing the energy performance of windows is to use the U value measurement (in the same way as quantifying the energy performance of walls, floors and roofs).
Glass manufacturers have mastered the art of coating and tinting glass. Low emissivity (Low-e) glass is used in energy efficient windows, which has an invisible metal oxide coating on the internal pane to keep the heat in, unwanted sunlight away, reduce glare and even self-clean, too. The net result of this glass engineering means the U values of glazing has been reduced dramatically.
- Single glazed windows can have a U value of around 5.0W/m²k
- Double glazed windows used to score over 3 and can now achieve under 1.4.
When an external window or door is replaced current Building Regulation now requires that any window you install should have a U value no worse than 1.6, while the Passivhaus standard requires triple glazed windows with a U value of no more than 0.8, and there are some suppliers who claim to achieve just 0.5.
These standards take into account the whole window or door, which includes the frame or internal elements, because it is not just the glazing that affects heat loss
As the U value demanded for walls is currently less than 0.3, it’s easy to see how old, drafty and inefficient windows can be significant weak spots in the overall thermal efficiency of a house.
Energy bill reductions for windows
The amount a typical home can save on heating as a result of fitting energy efficient windows and doors will depend on a number of factors influencing the overall energy efficiency of the property. An average saving when moving from single to double glazing is in the region of £95-£115 a year for a detached house, £65-£80 for a semi, £50-£60 for a mid-terrace house, to £30-£35 for a mid-floor flat.
Funding for upgrading to energy efficient doors and windows
Financial help for replacing old windows and doors varies between different areas of the UK and by funding schemes that are offered by local and national government. At the time of writing, the Green Homes Grant is just getting started, and while it mainly focuses on other forms of energy saving such as heating and insulation, help is available as part of the second tier funding to upgrade single glazed windows and old, thermally poor doors. Details of this scheme can be found here.
Choosing an installer
Look for installers that are members of the Fenestration Self-Assessment Scheme (FENSA), a government-backed Competent Person Scheme for the replacement of windows, doors and roof lights in England and Wales against relevant building regulations. As long standing members registered with FENSA, all windows and doors Newview fitters install fully comply with the latest thermal performance standards for energy efficiency.