Energy Efficient Windows: Warmer, Quieter, Smarter
As temperatures drop, it becomes easier to spot where warmth is escaping from your home, and windows are often a key source of heat loss.
Energy efficient windows are specially designed to tackle this problem, using advanced glazing, insulated frames and secure seals to keep more heat inside during winter and prevent rooms from overheating in summer.
Beyond improving energy performance, energy saving windows also reduce condensation, cut down on outside noise and create a more comfortable living space. While they do come with an initial cost, energy saving windows offer lasting value by lowering household bills and enhancing everyday comfort.
- How much could energy efficient windows save on heating bills?
Upgrading to A-rated energy efficient windows can dramatically reduce heat loss – by as much as 70% compared to older single glazing or underperforming double glazing. For many UK households, that means saving between £100 and £300 each year on heating bills in a typical semi-detached home. Larger or detached properties often see even bigger reductions, thanks to having more window space and higher overall energy use. Your exact savings will depend on several factors, including the window’s U-value, airtightness, the size and number of windows, your home’s insulation levels, and property type. - Double or triple glazing – which should you choose?
For most UK homes, modern double glazing is more than up to the task. Double glazed high performance windows offer excellent energy efficiency, comfort, and value, thanks to advanced glazing technology and well-insulated frames. Triple glazing can be worthwhile in certain cases, such as homes in particularly cold or exposed areas, north-facing rooms, or where outside noise is an issue, but for the majority of properties, quality double glazing delivers everything you need without the extra expense. - What about frame materials – UPVC, aluminium or timber?
UPVC frames are known for their multi-chamber design, giving strong insulation at an affordable cost. Aluminium frames, when manufactured with thermal breaks, also provide impressive efficiency while achieving slim, contemporary sightlines, though they tend to be pricier. Timber, as a natural insulator, is another great performer but requires more maintenance to keep it looking its best. It’s also worth noting that the opening style and sealing (casement, sash, tilt & turn) play a big part in performance, along with longevity and overall budget. Speaking with an Eden Windows advisor is the easiest way to weigh up the options and choose what’s right for your home. - What U-value and BFRC rating should you choose?
The U-value tells you how much heat a replacement window lets escape, measured in W/m²K. The lower the figure, the better its insulating ability. The BFRC Window Energy Rating (WER), graded from A++ down to C, gives a quick overall view of efficiency.
For UK homes, it’s best to look for low whole-window Uw values alongside strong WER scores. Just make sure you’re comparing like-for-like specifications when assessing energy efficient windows, as frame type, glazing, and seals all affect the final rating.
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How Insulated Windows Improve Heat Retention and Solar Gain
Insulated windows are designed to combat heat loss in three ways: conduction, convection, and radiation. Low-E coatings reflect warmth back into your rooms, inert gas fills slow down heat transfer between panes, and warm-edge spacers reduce energy loss around the edges.
Working together, these features deliver excellent thermal efficiency, help lower heating costs, and regulate solar gain, meaning you still enjoy plenty of natural light while keeping your home warmer for longer.
Low-E glass and how it boosts efficiency
Low-E (low-emissivity) glass is designed with a virtually invisible metallic coating that reflects heat back into your living space while still allowing plenty of natural light through.
The result is your home stays warmer in winter, cooler in summer, and far more comfortable all year round. This smart coating makes today’s windows significantly more efficient than older glazing, helping you save energy and reduce bills.
Gas fills & warm-edge spacers (argon, krypton, xenon)
Between the panes of glass, inert gases such as argon, krypton, or xenon are used to slow down heat transfer. Alongside this, warm-edge spacer technology reduces thermal bridging at the window’s edges.
Together, these details help lower condensation, improve U-values, and keep indoor temperatures steady. Small changes like these have a big impact on overall energy efficiency and day-to-day comfort.
UPVC, Aluminium or Timber – Which Frame Offers the Best Efficiency?
UPVC frames are highly insulating, low maintenance, and built to last for decades, making them a popular choice. Aluminium frames, when fitted with thermal breaks, provide strength, slim sightlines, and durability, though they don’t insulate quite as well as UPVC. Timber frames naturally insulate too, but their efficiency can decline over time as they require more upkeep and are less durable overall.
Your frame choice will influence not only thermal performance, but also longevity, aesthetics, and how efficient your windows are in real-world conditions when paired with quality glazing.
Which Window Styles Perform Best – Casement, Sash, or Tilt & Turn?
The chosen window styles also affect efficiency, particularly in how tightly each style seals against draughts. Casement and tilt & turn windows generally offer the most secure seal, helping to prevent heat loss and keep energy bills lower, often making them the best energy efficient windows.
Traditional sash windows, while charming, can allow more air movement unless specially designed for efficiency.
Selecting a well-sealed, modern style is key to reducing draughts, cutting heating costs, and keeping your home comfortable. For tailored advice, the Eden team can guide you through the best options for your property.
Window Ratings in the UK (BFRC, WER & U-values)
Windows in the UK are assessed for efficiency using two key measures: BFRC Window Energy Ratings (WER) and U-values. WER grades range from A++ (the best) down to C, showing the performance of the whole window. U-values, measured in W/m²K, show how much heat escapes – the lower the number, the better the insulation.
WER looks at the full picture, including glass, frames, and seals, while U-values focus only on heat transfer. By considering both, you’ll get a more accurate understanding of how well a window will actually perform in your home.
What does a Window Energy Rating mean and how does the BFRC scale work?
A Window Energy Rating (WER) is designed to make comparing windows simple. It reflects the efficiency of the complete unit, frame, glazing, and sealing, not just the glass. The BFRC label runs from A++ to C, giving you a clear benchmark of performance. By checking the WER, you can be confident that your new windows will deliver real energy savings and all-round efficiency, rather than just relying on high-rated glass.
Understanding U-values (and why they matter)
A U-value shows how much heat a window lets through. What is a good u value for windows? Well, the lower the number, the better the insulation. Uw represents the performance of the whole window (glass, frame, and seals), while Ug measures just the centre pane of glass. To give some context:
- 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.
A, B, or C-rated windows – what’s the difference?
As part of the Window Energy Rating (WER) system, A, B, and C-rated windows each provide different levels of efficiency. A-rated windows deliver the best performance, helping your home stay warmer for longer and reducing energy use. C-rated windows still comply with building regulations and are often the more affordable option, but they won’t offer the same comfort or savings as higher-rated choices.
The WER scale runs from A+ (the most efficient) down to G. Choosing to upgrade from a C rating to an A rating can make a real difference, from fewer draughts and warmer rooms to noticeable reductions in your heating bills.
Double or Triple Glazing – What’s Best for UK Homes?
For most homes in the UK, high-quality double glazing strikes the right balance of performance, comfort, and affordability. It keeps warmth in, cuts draughts, and is more than capable of meeting everyday household needs.
Triple glazing can be worth considering if you live in a particularly cold or exposed location, have north-facing rooms, or want extra sound insulation. However, it does come with higher costs, heavier units, and frame considerations.
In reality, the best option depends on your home and what you value most, but for the majority of properties, modern double glazing offers all the efficiency and comfort you’ll need.
High-Performance, Thermally Efficient Windows – What You Need to Know
Picking the right insulated windows is all about understanding the key ratings and specifications. We can help you compare WER and U-values, decide between double and triple glazing, and choose frame materials that strike the right balance of energy efficiency, style, and upkeep.
As a homeowner, it’s important to weigh costs against potential savings, plan for professional installation and ventilation, and always compare like-for-like from accredited installers, such as Eden Windows.
Our knowledgeable and friendly team can guide you toward the perfect window style and material, helping to reduce energy bills, improve comfort, and future-proof your home with our very best energy efficient windows. With careful selection, high performance windows aren’t just an upgrade, they’re an investment that pays off year after year.
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