Understanding Double Glazing Ratings: A++, U-Values & More

When you’re upgrading your home with new windows, it’s natural to want the very best in performance, style, and long-term value. At Stormshield Windows & Conservatories, we’re proud to help homeowners across the UK make informed decisions about their investments. 

From A++ ratings to U-values, energy labels can sometimes feel like a confusing set of numbers and letters. But in truth, they’re designed to make it easier for you to compare products and ensure your home is fitted with energy efficient double glazing that reduces heat loss, lowers your bills, and improves comfort year-round.

In this guide, we’ll walk you through everything you need to know about double glazing ratings, explain how they’re measured, and show you why they matter. Along the way, we’ll also share how our range of products, from windows and composite doors to conservatory roofs and home extensions, can transform your property.

Introduction to Double Glazing

We provide double glazing as a modern solution for homeowners seeking to boost their property’s energy efficiency and comfort. At its core, our double glazing features two panes of glass separated by a spacer bar, with the gap between the panes typically filled with an inert gas like argon. This clever design acts as a barrier, significantly reducing heat transfer between the inside and outside of your home.

When we install our double-glazed windows, you can expect a dramatic reduction in heat loss compared to traditional single-glazed windows. This means your home stays warmer in winter and cooler in summer, leading to lower heating bills and less energy consumption overall. The improved thermal insulation provided by our double glazing also helps to cut down on your carbon footprint, making your home more environmentally friendly.

Beyond energy efficiency, our double glazing offers enhanced security performance and helps to reduce external noise, creating a quieter, safer, and more comfortable living environment. Whether you’re upgrading from single-glazed windows or fitting new energy-efficient glazing for the first time, our double-glazing represents a smart investment in your home’s future.

Why Double Glazing Ratings Matter

Windows are one of the biggest sources of heat loss in any home. Poorly insulated or outdated windows can let warmth escape in the winter and allow unwanted heat in during the summer. This not only affects your comfort but also leads to higher energy bills.

Double glazing is cost-effective over its typical 20-year lifespan, helping to reduce your energy costs year after year. The right windows can:

• Keep your home warmer in the winter and cooler in the summer

• Reduce your reliance on central heating

• Lower your energy bills

• Minimise your home’s carbon footprint

• Add long-term value to your property

  
  

But how do you know which windows are the most efficient? That’s where ratings like A++ and U-values come into play.

The Window Energy Rating (WER) System

The Window Energy Rating (WER) system is a simple way of understanding how well a window performs. It works similarly to the energy labels you’ll see on fridges or washing machines.

• Ratings range from A++ (the highest possible efficiency) down to E (the least efficient).

• The higher the rating, the better the window is at retaining heat while letting natural light in.

• An A++ rated window is designed to keep heat in your home and save you money in the long run.

• The window U-value is a key metric used in the WER system, measuring how much heat transfers through the window and indicating its overall insulation performance.

At Stormshield, we supply and install windows that meet the highest efficiency standards. By choosing our A-rated or A++ rated energy efficient double glazing, you’re investing in long-lasting quality and performance.

What Are U-Values?

Alongside the WER, you’ll often see U-values mentioned when looking at double glazing. A U-value measures the amount of heat lost through the window.

• The lower the U-value, the less heat lost and the better the insulation.

• A standard single-glazed window may have a U-value of around 5.0 W/m²K.

• Modern double glazing usually sits between 1.2 and 1.6 W/m²K.

• Triple glazing can achieve even lower values, sometimes below 1.0 W/m²K.

When comparing options, it’s worth looking at both the energy rating and the U-value. Together, they give you a clear picture of how well your windows will perform.

The Role of Glass, Frames, and Installation

Energy ratings aren’t just about the glass. The overall performance of your windows depends on several factors. An energy-efficient window is specifically designed to minimize heat transfer and maximise insulation, helping to keep your home comfortable and reduce energy bills. Having energy efficient glazing installed can improve comfort, lower heating and cooling costs, and increase the value of your property. Energy efficient windows also help manage thermal energy, keeping homes warmer in winter and cooler in summer.

• Glass technology: Low-emissivity (Low-E) glass reflects heat into your home while still letting light through, and can help control solar gain.

• Gas-filled units: Argon or krypton gas between panes reduces heat transfer, reducing heat loss and improving insulation.

• Warm edge spacers: These help to reduce condensation and heat loss around the edges by reducing heat transfer.

• Triple glazed windows: Triple-glazed windows use a multi-pane structure with insulating gas to provide enhanced insulation, reducing heat loss, noise, and drafts.

• Frames: The window frame is a key component in energy efficiency. The frame material and frame materials used, such as uPVC, aluminium, and wood, significantly impact the thermal performance of the window frame. uPVC windows feature multi-chamber profiles for better insulation, aluminium frames often include a thermal break to improve insulation, and wood frames offer natural insulating properties. Choosing the right frame materials is essential for maximising energy efficiency.

• Sash windows: Sash windows are a traditional style commonly found in period properties, and can be upgraded with modern glazing and frame materials to improve energy efficiency while preserving their classic appearance.

• Professional installation: Even the best-rated window won’t perform properly if it isn’t installed correctly.

The overall energy efficiency is determined by the entire window, including both the glass and the window frame, as assessed by rating schemes like BFRC.

At Stormshield, we only use trusted, high-quality materials and provide expert installation. That way, you can be sure your new windows deliver exactly what the ratings promise.

A++ Windows vs A Rated Windows

So, should you always choose the highest possible rating? Not necessarily, it depends on your priorities.

• A rated windows already provide excellent efficiency and may be a more cost-effective option.

• A++ windows offer the very best insulation and long-term energy savings, making them ideal if you want maximum performance.

We’ll always take the time to discuss your home, budget, and long-term goals to help you choose the right solution.

Energy Efficient Double Glazing and Your Bills

One of the biggest benefits of installing our energy efficient double glazing is the savings you’ll see on your bills. The Energy Saving Trust suggests that upgrading from single glazing to A-rated double glazing can save you hundreds of pounds per year, depending on the size of your property. For example, a typical detached house can see even greater savings and lower installation costs per window compared to smaller property types, due to larger window sizes and higher heating requirements.

Over time, the investment pays for itself, while also making your home more sustainable and comfortable.

Other Benefits Beyond Efficiency

While energy efficiency is often the main focus, modern double glazing offers several other advantages:

• Noise reduction: Keep unwanted traffic or neighbourhood noise at bay. Sealed window units with features like argon gas and advanced spacers help in reducing noise pollution from external sources by minimising sound transmission.

• Enhanced security: Multi-point locking systems and toughened glass improve home safety.

• Increased property value: Energy-efficient homes are highly attractive to buyers.

• Style and choice: From sleek aluminium to traditional uPVC frames, our designs complement your home’s character.

Regulations and Compliance

When we install new energy-efficient windows and doors, it’s essential to ensure that our upgrades meet all relevant regulations and standards. The British Fenestration Rating Council (BFRC) provides a trusted rating system for energy-efficient windows, with ratings ranging from A++ (the highest) down to E. This system helps us easily compare the energy efficiency of different products and make informed choices.

Another important measure is the U-value, which indicates how well a window prevents heat from passing through. Lower U-values mean better insulation and improved energy efficiency, which can lead to significant savings on our energy bills.

To guarantee that our new windows and doors deliver the best possible performance, we should always choose products that meet or exceed the required energy efficiency standards. It’s also important to have our windows installed by a reputable, certified professional. Proper installation ensures compliance with regulations, maximises the benefits of our new windows, and helps us enjoy improved energy efficiency and lower energy bills for years to come.

Financing Options for Double Glazing

We believe that investing in double glazing is a brilliant way to improve your home’s energy efficiency, but we understand that the upfront cost can be a concern. Fortunately, we can offer a variety of financing options to make installing energy-efficient windows and doors more accessible. Many of us in the window industry provide flexible payment plans, allowing you to spread the cost of your new windows over several months or years, making it easier to manage your budget.

In addition to our company financing, you may be eligible for government schemes or incentives designed to encourage energy-saving improvements, such as grants or low-interest loans for energy-efficient upgrades. We find that these programmes can help offset the initial investment and make it even more affordable to upgrade to double glazing.

When we discuss new windows with our customers, we always recommend factoring in the long-term savings on your energy bills, the potential increase in your property’s value, and the positive impact on your carbon footprint. By exploring the financing options we offer and understanding the benefits of energy efficient glazing, you can make a confident, informed decision that enhances your home’s comfort, security, and sustainability.

Other Services We Offer

At Stormshield, we’re about more than just windows. We offer a wide range of products and services to help you transform your home:

• Doors: From secure front doors to elegant patio doors, we supply and fit styles that combine security, efficiency, and curb appeal.

• New conservatory roofs: If your existing conservatory is too hot in summer or too cold in winter, a new insulated roof can make it usable year-round.

• Guardian conservatory roofs: These innovative tiled roofs provide thermal efficiency while giving your conservatory the feel of a proper extension.

• Extensions: Add valuable living space to your home with a bespoke extension designed and built by our experienced team.

• Bathrooms: Whether you’re after a stylish update or a full renovation, we create bathrooms that are as practical as they are beautiful.

By offering these additional services, we can help you improve every corner of your home, all with the same level of quality, expertise, and care.

Choosing the Right Windows for Your Home

When it comes to picking new windows, it’s important to think about more than just ratings. We always recommend considering:

• Your budget: A+ or A++ rated windows may cost more initially, but will offer bigger savings over time.

• Your property style: From modern homes to period properties, we’ll help you choose frames that complement your home’s look.

• Your priorities: Whether you want maximum efficiency, noise reduction, or a balance of both, we’ll guide you to the right solution. Keep in mind that single-pane windows have much poorer insulation compared to double or triple glazing, making them less suitable for energy efficiency upgrades.

  
  

Why Choose Stormshield?

With so many companies offering double glazing, why should you choose us?

• Trusted expertise: We have years of experience helping homeowners across the UK.

• Tailored advice: We don’t believe in one-size-fits-all. We’ll help you find what works best for your home.

• Quality products: We only supply windows, doors, and conservatory roofs that we’d be proud to have in our own homes.

• Customer care: From first consultation to final installation, we’re here to make the process smooth and stress-free.

When you choose Stormshield, you’re not just buying windows; you’re investing in long-term comfort, efficiency, and peace of mind.

Final Thoughts

Understanding double glazing ratings doesn’t need to be complicated. At Stormshield Windows & Conservatories, we’re here to make it simple. Whether you’re looking for A++ rated energy efficient double glazing or want to explore our full range of home improvement services, we’ll help you make the right choice for your property.

With rising energy costs and growing awareness of sustainability, now is the perfect time to invest in windows that will improve your comfort, lower your bills, and add real value to your home.

Ready to Upgrade Your Windows?

If you’d like to learn more about our energy-efficient double glazing or any of our other services, from doors and conservatory roofs to extensions and bathrooms, we’d love to hear from you.

Contact Stormshield Windows & Conservatories today to arrange your free consultation.