If you’re comparing new windows for your home or business, you’ll notice every product has an energy rating – from A down to G.
But what do these ratings actually mean? And why do they matter for your comfort, energy bills, and property value?
In this guide, we’ll break down the Window Energy Rating (WER) system, explain what’s changed in 2025, and help you make the right choice when upgrading your glazing in Bournemouth, Poole, Christchurch, and surrounding Dorset areas.
What Are Window Energy Ratings?
Window Energy Ratings (WERs) are a standardised system used in the UK to measure how energy-efficient a window is.
They are graded from:
🟩 A++ – Most efficient
🟨 B–C – Good
🟥 G – Least efficient
These ratings are determined by the British Fenestration Rating Council (BFRC) and are based on:
- 🔥 Heat retention (U-value)
- ☀️ Solar gain (G-value)
- 🌬️ Air leakage (L-value)
2025 WER Grading System – What’s Changed?
As of 2025, the UK rating system has aligned more closely with appliance-style labels, introducing A++ down to G, replacing the older A–C system used for windows.
| Rating | Description | Suitable For |
|---|---|---|
| A++ | Exceptional insulation and performance | New builds, eco-homes |
| A+ | Excellent thermal performance | Energy-conscious homes |
| A | Meets current building regulations | Most modern homes |
| B–C | Older standard glazing | Often acceptable but less efficient |
| D–G | Poor performing windows | Likely single-glazed or dated double glazing |
Why Energy Ratings Matter
Replacing your windows isn’t just about appearance — it’s about performance. Here’s why choosing A-rated windows is a smart move:
Lower Energy Bills
Modern A-rated double glazing reduces heat loss, meaning your boiler doesn’t have to work as hard in winter.
According to the Energy Saving Trust, upgrading from single glazing to A-rated double glazing can save up to £155/year on heating.
Warmer, More Comfortable Rooms
No more draughts or cold spots near windows. A-rated units keep internal temperatures more stable.
Improved EPC Rating
If you plan to sell or rent, installing efficient glazing can boost your Energy Performance Certificate (EPC) – now a critical part of property valuations.
Better for the Environment
Reduced heating = lower carbon emissions = better for the planet.
Do All New Windows Meet A Ratings?
Surprisingly, not all modern windows are A-rated – and some budget options on the market still fall below B or C. Always ask your installer for proof of certification from BFRC or CERTASS.
At JCarter, we only install A-rated or higher glazing units, ensuring full compliance and long-term energy performance.
Key Window Performance Metrics Explained
| Metric | Description | What to Look For |
|---|---|---|
| U-value | Measures heat loss | Lower is better (e.g. 1.4 W/m²K or lower) |
| G-value | Measures solar heat gain | Depends on orientation – too high may cause overheating |
| L-value | Air leakage rate | Lower is better – modern windows should have minimal leakage |
How to Check Your Current Windows
Not sure how your windows rate? Look for:
- Manufacturer labels in the glazing unit
- Dates or certifications on the frame
- Draughts or cold spots (a sign of poor insulation)
- Condensation inside the unit (could mean it’s blown)
If you’re unsure, we offer a free window efficiency check across Bournemouth and Dorset.
Areas We Cover
We install and upgrade A-rated energy-efficient glazing across:
- Bournemouth
- Poole
- Christchurch
- Ferndown
- Wimborne
- Southbourne
- Ringwood
- Across Dorset & Hampshire
Looking for A-rated double glazing near me? JCarter Glazing can help.
FAQs – Energy Efficient Windows
Will I need triple glazing to get an A++ rating?
Not necessarily. Some double glazed units with low-E coatings and warm edge spacers achieve A++ ratings. We’ll advise based on your property type and budget.
Is A-rated glazing more expensive?
Usually yes – but the long-term savings on energy bills and reduced maintenance make them more cost-effective overall.
Do A-rated windows come in different styles?
Absolutely – we offer casement, tilt-and-turn, sash, flush-fit and more – all A-rated and fully customisable.
