Energy Efficient Windows - Expert Picks & Tips
There are hints of colder weather on the horizon as we edge into autumn and you may be noticing it at home – if so, your windows could be the source of that.
Energy efficient windows are essential for keeping the house warm and on the flip side, avoiding it overheating during the summer months. They encompass contemporary glazing, airtight seals and advanced frames to restrict heat loss to a minimum in comparison to ageing single glazing or low-quality double glazing windows.
Additionally, they can reduce condensation and the amount of external noise heard from indoors. There’s no denying that energy saving windows need a decent investment, but they’ll repay you with cheaper energy bills and an improved lifestyle.
- How much money will I save on heating thanks to energy efficient windows?
Switching to A-rated energy efficient windows from old single glazing or below par double glazing can cut heat loss by as much as 70%. A yearly saving of about £100-£300 on heating costs is achievable for people living in a semi-detached UK home. There’s the potential for increased savings at detached or large dwellings because of their larger window sizes and higher energy demand. Savings will be dependent on things like U-values, airtightness, the overall window area, house type and existing insulation. - Would my UK home most profit from double or triple glazing?
Triple glazed windows are often promoted as the best option, but modern double glazing is more than suitable for most UK properties, delivering exceptional energy efficiency, warmth and being highly affordable. Triple glazing comes into its own in very cold climates, north-facing rooms, or when you want to shut out external noise. - Is UPVC, aluminium or timber the most energy efficient material?
A UPVC frame is multi-layered for top-class insulation, while aluminium comes with thermal breaks but costs more, with timber being the most naturally insulating of the three, however it’s also the hardest to maintain. Performance is subject to the choice of frame and opening, as well as sealing, lifespan, cost and sightlines. Some conversation with one of our design experts will clarify the most appropriate window for your house and budget. - What U-value and BFRC rating do I aim for?
A windows u value denotes heat loss (W/m²K). Low U-values are what you want, with the BFRC Window Energy Rating (A++ to C) representing overall energy efficiency. It’s recommended to target whole-window Uw and WER targets for UK residences and compare like-for-like specifications when looking into energy saving windows.
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The full facts about insulated windows
Insulated windows can gradually decrease heat through the processes of conduction, convection and radiation. They include Low-E coatings that reflect heat back inside, in addition to gas fills to lessen conductive losses and warm-edge spacers for minimising heat escape at the window edges.
The amalgam of ingredients in the sealed units help windows provide superior thermal performance, cut energy costs, control solar gain and preserve warmth.
Explaining Low-E glass and its effect on energy efficiency
Low-E (low-emissivity) glass has a microscopic metallic coating that reflects heat back into your home while letting light through. Essentially, it keeps warmth inside in winter and reduces overheating in summer, helping windows save energy and improve comfort. Low-E coatings make modern glazing far more efficient than older units.
Gas fills & spacers (argon/xenon/krypton, warm-edge technology)
Heat transfer between panes is reduced by gas fills such as argon, xenon or krypton, with warm-edge spacers cutting thermal bridging at the frame.
They cut the threat of condensation, amplify U-values and ensure a consistent indoor temperature is maintained.
These small enhancements noticeably uplift energy efficiency and comfort, improving your everyday living experience.
UPVC, Aluminium or Timber – which is the most energy efficient frame?
UPVC window frames are excellent insulators, need minimal upkeep and can endure for years. Aluminium frames and their thermal breaks insulate well and offer a slim and robust profile. Timber naturally insulates, but its weakness is how quickly it ages and how much effort needs exerting to preserve its look and condition.
Frame selection has an influence on e.g. thermal performance, longevity, sightlines and appearance.
Are casements, sash or tilt and turn windows the most efficient style?
Window sealing and the choice of window style affects the standard of energy efficiency provided by different types of windows for a home. Information on draught proof windows and the best energy efficient windows can be sought from TWC’s team of advisors.
Casement windows and tilt and turn windows tightly close and therefore restrict draughts and heat loss, but classic sash windows are sometimes guilty of leaking more air.
To lower heating bills and boost home comfort, prioritise well-sealed, high-performance windows.
How window ratings work in the UK (BFRC, WER & U-values)
The energy performance of windows sold in the UK is symbolised in BFRC Window Energy Ratings (WER), from A++ to C, signifying their overall energy efficiency. U-values represent the amount of heat that escapes through a window, with a low U-value being what to look for.
There is some relation between the two, but WER refers to glazing, framing and sealing, while U-values are focused on heat transfer.
A comparison of both things will point you towards high performance windows that embody everything you’d want in modern replacements.
What are window energy ratings and how do BFRC ratings work?
Window Energy Ratings (WERS) are designed to tell you how efficient an entire window is, considering its frame, glazing and seals. BFRC labels span from A++ (finest) to C, helping you to compare options. Pay attention to WERs if you want the best performing windows offering all-round efficiency.
The significance of U-values and understanding them
A U-value is a measurement of how much heat escapes from a window (low U-values provide the best insulation). Uw = whole window value, Ug = centre-pane glass only. Typical ranges:
- Single glazing: 5.0–6.0 W/m²K
- Old double glazing: 2.8–3.0 W/m²K
- Modern A-rated windows: 1.2–1.6 W/m²K. Concentrating on Uw guarantees true thermal performance.
How A, B and C-rated windows differ
In accordance with the Window Energy Rating (WER) scheme, A, B and C-rated windows offer varied levels of energy efficiency. The most energy efficient of the lot are A-rated windows, which retain abundant heat and shrink energy usage, with C-rated windows being the minimum accepted windows for adhering to building regulations and the cheapest to buy.
The Window Energy Rating (WER) system uses a scale of A+ to G (A+ rated windows rank first for energy saving). A transition from C to A-rated windows will have an enormous impact on home comfort – virtually eliminating draughts, heating up rooms and cutting energy costs.
Double Glazing vs Triple Glazing - Which Is Right for UK Homes?
For most UK homes, modern double glazing is sufficient, balancing efficiency, comfort, and cost. Triple glazing may suit colder regions, exposed sites, north-facing rooms, or homes where noise reduction is a priority, but comes with added weight, cost, and frame considerations.
The right choice depends on your property and goals, and our high performing double glazing is usually sufficient for most homes in the region.
Summarising high performance, thermally efficient windows
Discerning what are insulated windows requires some awareness of energy ratings and specifications. TWC is here to help you understand WER and U value windows, figure out whether to invest in double or triple glazing and guide on frame materials.
Before committing to anything, evaluate the cost involved against the potential savings, ensure that you arrange a professional installation and only approach accredited installers, just like TWC.
Our advisors will do whatever they can to direct you to the correct window material and style so that energy bills become less of a burden and your heating system gets more of a break.
With TWC as your home improvement partner, cheaper energy and elevated comfort is a certainty as our window replacements are a reliable upgrade.
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We have a fantastic range to choose from so whether it’s a modern style or traditional timber effect windows – we are confident that we will have windows to improve any home to give it the finished look with elegance.
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