Upgrade to Energy Efficient Windows Without Guesswork
As winter gets closer, it’s often the little draughts and cold spots that give away where a home is losing heat, and more often than not, the windows are to blame.
That’s where energy efficient windows make a real difference. The best energy efficient windows are built with clever glazing technology, snug seals and modern frames, they’re designed to hold onto warmth in the colder months and keep your home feeling cooler when summer rolls around.
On top of that, energy saving windows can cut down on everyday nuisances like condensation and outside noise. They’re an investment, but one that pays back through lower bills, greater comfort, and a cosier place to call home.
- How much would I save in heating costs if I switched to energy efficient windows?
Switching to modern, energy efficient windows can make a noticeable dent in your heating bills. In fact, replacing old single glazing or tired double glazing with A-rated windows can cut heat loss by as much as 70%. For a typical semi-detached home in the UK, that usually translates to savings of around £100–£300 a year. If you live in a detached or larger property, the figure is often higher, simply because there’s more glass and more energy demand overall. The exact savings depend on factors like the window’s U-value, how airtight they are, the total window area, your property type and the quality of your insulation. - Is triple glazing worth it, or will modern double glazing do the job?
It’s a common question, but for most homes in the UK, modern double glazing is more than enough. Today’s double glazed high performance windows are built with advanced technology that keeps the warmth in, cuts draughts and offers excellent value for money. Triple glazing can be beneficial in certain situations – like very cold or exposed locations, north-facing rooms, or if you want to reduce outside noise even further, but for the majority of properties, high-quality double glazing windows deliver all the comfort, efficiency and performance you’ll need without the extra cost. - UPVC, aluminium or timber – which is best for energy efficiency?
Each has its strengths. UPVC frames use a clever multi-chamber design that offers excellent insulation at a good price point. Aluminium frames, when fitted with thermal breaks, also perform well and give a sleek, modern look, though they can be a little more expensive. Timber, being a natural insulator, is another strong option but does require more upkeep over time.
It’s also worth remembering that efficiency isn’t just about the material as the window style, how it opens, and the quality of the sealing (whether casement, sash or tilt & turn) all play a role, alongside factors like lifespan, cost and sightlines.
The best option really depends on your home and priorities, so a chat with a Bon Accord advisor can help you find the perfect fit for both performance and budget. - What U-value and BFRC rating is recommended?
A U-value shows how much heat escapes (W/m²K). The lower it is, the better the insulation. The BFRC Window Energy Rating, graded from A++ down to C, gives you an easy way to see overall efficiency.
For UK homes, it’s best to look for whole-window Uw values and WER ratings that meet recommended standards, and always check you’re comparing like-for-like specifications when weighing up energy efficient windows.
Request Your Free Window Quote
Simply fill in your details for your free, no obligation quotation
The Role of Insulated Windows in Heat Loss and Solar Gain
Insulated windows limit heat loss through conduction, convection, and radiation. Low-E coatings bounce warmth back indoors, inert gas fills cut down on conductive transfer, and warm-edge spacers reduce edge-related heat escape.
As a whole, these sealed units deliver excellent thermal efficiency, reduce energy costs, and regulate solar gain, allowing natural light to enter while keeping heat inside.
What is Low-E glass and how will it improve energy efficiency?
Low-E (low-emissivity) glass features an ultra-thin metallic coating that reflects heat back into the home while still allowing natural light to pass through. This means it retains warmth during winter and limits excess heat in summer, making replacement windows more energy-efficient and improving year-round comfort. With Low-E coatings, today’s glazing performs far better than older, less efficient units.
Gas fills & spacers (argon/xenon/krypton, warm-edge technology)
Gas fills such as argon, krypton, or xenon limit heat transfer between panes, while warm-edge spacers reduce thermal bridging around the frame. Together, they lower the risk of condensation, improve U-values, and support a steady indoor temperature. These small enhancements make a big difference, greatly improving energy efficiency and day-to-day comfort.
UPVC, Aluminium or Timber – Which Frame Offers the Best Energy Efficiency?
UPVC frames provide excellent insulation, need minimal maintenance, and can last for decades. Aluminium with thermal breaks is slim, durable, and strong, though generally less insulating than UPVC. Timber is a natural insulator, but higher upkeep and a shorter lifespan can reduce its long-term energy efficiency.
Your choice of frame influences thermal performance, durability, aesthetics, sightlines, and overall efficiency (particularly when combined with high-quality glazing).
Casement, sash, tilt & turn - Which window style is the most efficient?
Different window styles influence energy efficiency in how well they seal. For tailored advice on draught-proofing and choosing the most efficient windows to retain heat, speak to the team at Bon Accord.
Types of window frames like casement and tilt & turn windows shut firmly to reduce draughts and heat loss, whereas traditional sash designs can allow more air leakage.
Opting for well-sealed, high-performance windows helps lower heating bills and enhances comfort throughout your home.
How Windows Are Rated in the UK (BFRC, WER & U-values)
In the UK, window efficiency is measured using BFRC Window Energy Ratings (WER), graded from A++ down to C, which reflect the overall performance of the complete window. U-values measure how much heat passes through, with lower numbers indicating better insulation.
While linked, WER considers glazing, frame, and sealing, whereas U-values focus solely on heat transfer.
Looking at both ratings together helps ensure you select truly high-performing windows, rather than just glass with a strong rating.
What is a Window Energy Rating and how does the BFRC system work?
A Window Energy Rating (WER) measures the overall efficiency of a complete window, including the frame, glass, and seals. The BFRC scale ranges from A++ (highest) to C, providing a straightforward way to compare different products. Using WERs helps homeowners identify truly high-performing windows, ensuring energy savings come from the whole unit, not just the glazing.
Why U-values Matter (and How to Understand Them)
U-values indicate how much heat passes through a window. If you’re wondering is a lower u value better then you’d be correct. The lower the figure, the better the insulation. Uw refers to the value for the whole window, while Ug measures the centre-pane glass only. Typical ranges include:
- 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. Focusing on Uw ensures true thermal performance.
Explaining the Difference Between A, B, and C-rated windows
A, B, and C-rated windows sit at different points on the Window Energy Rating (WER) scale, each offering varying levels of efficiency. A-rated windows perform best, holding in more warmth and cutting energy use. C-rated windows meet the minimum building regulation standard and are usually cheaper, but they don’t deliver the same comfort or savings as A or B-rated options.
The WER system runs from A+ down to G, with A+ being the best energy efficient windows. Upgrading from C to A-rated windows can noticeably improve comfort – these energy saving windows result in fewer draughts, cosier rooms, and lower bills.
Double Glazing vs Triple Glazing - Which Is Right Homes in the UK?
For the majority of UK homes, modern double glazing provides the ideal balance of energy efficiency, comfort, and affordability. Triple glazing windows can be a good option in colder climates, exposed locations, north-facing rooms, or where noise reduction is a key concern, though it does involve higher costs, heavier units, and specific frame requirements.
Ultimately, the best choice depends on your property and priorities, but in most cases, our high performance double glazing more than meets household needs in this region.
The Essentials of High-Performance, Thermally Efficient Windows
Choosing the right insulated windows starts with understanding ratings and specifications. We can help you compare WER and U values, weigh up double versus triple glazing, and advise on frame materials that balance energy efficiency, style, and maintenance.
As a homeowner, it’s important to consider costs alongside realistic savings, plan for professional installation and ventilation, and always compare like-for-like from accredited installers, such as Bon Accord.
Our friendly, experienced team is on hand to guide you to the right window material and style, helping manage rising energy costs and ease pressure on your heating system. Choosing high performance with Bon Accord means lower bills, greater comfort, and an investment in windows that enhance your home for years to come.
REQUEST YOUR FREE QUOTE
Simply fill in your details for your free, no obligation quotation, and click "Get Quote"
Want to speak with an Advisor? Give us a call on 01224 588944
Our friendly team will be pleased to help with any questions you may have.