Understanding Window Energy Ratings

When shopping for new windows for your property, one term that you will likely see mentioned is U-values and WERS (Window Energy Rating Scheme). Understanding these systems can greatly influence the choices you make in construction and renovation. In this blog, we will delve into U-values and WERS to explain how they impact window performance.

What are U-values?

U-values are an indicator of thermal performance for building elements, such as windows. They measure the rate of heat transfer through windows and are crucial in assessing energy efficiency. U-values also measure how much heat loss occurs through a given material, measured in watts per square metre per Kelvin (W/m2). This figure is calculated by dividing the difference in temperature across a building element by the rate of heat transfer. The lower the window’s U-value, the better it performs at insulating against heat loss. Factors such as glazing options and frame material help define a window’s overall thermal efficiency.

What are WERS?

The Window Energy Rating System was launched in the UK by the British Fenestration Rating Council, a government-supported independent body that allows consumers to reliably compare one product with another. It provides a standardised rating that indicates how well a window performs in terms of heat loss, solar gain, and air leakage. These elements collectively determine the overall energy efficiency of a window. This provides a much more comprehensive rating than the U-value.

A higher WERS rating means the window is more effective at improving a building’s energy efficiency, reducing heating and cooling costs, and enhancing indoor comfort.

What constitutes a good energy rating?

If compliant with building regulations, all modern windows will have a U-value of at least 1.4 and a WERS rating of B. These regulations are due to change again in 2025 as part of the Future Homes Standard.  These are the bare minimum ratings that you should be on the market for, as anything lower becomes too inefficient. More then that, though, it is a legal requirement.

SCI replacement windows incorporate the very latest glazing technology, and PlatinumNRG double-glazed PVCu casement windows achieve the ‘greenest’ Window Energy Ratings (WER) rating of A+9 for energy efficiency.

Do energy ratings really make an impact?

Absolutely, energy ratings have a significant impact on both the comfort of your home and your energy bills. The key to understanding this lies in how these ratings translate into real-world benefits.

Reduced energy costs

One of the most immediate impacts of choosing windows with excellent energy ratings is the reduction in energy costs. A window with a low U-value and high WERS rating is designed to minimise heat loss during the winter and reduce heat gain in summer. This means that you are using your central heating and air conditioning less, leading to savings on your energy bill.

Enhanced comfort

Energy-efficient windows do more than just cut costs; they also improve the overall comfort of your home and make a noticeable difference in your living spaces. By reducing drafts and cold spots near windows, it maintains a more consistent temperature.

Longevity and durability

Windows with high WERS and low U-values are often made with better materials and construction techniques. This means that they are likely to be more durable and have a longer lifespan. This can save you money in the long run by reducing the likelihood of costly repairs.

Increased Property Value

Investing in windows with good energy ratings can also boost the value of your property. As energy efficiency becomes a growing concern for homeowners and buyers alike, having high-performance windows can be a strong selling point. Some buyers are often willing to pay more for a home that is already energy efficient for the previously mentioned benefits.

Are windows with high energy ratings worth it?

While the upfront costs may be higher, energy-efficient windows should be seen as an investment rather than a purchase. You would be saving hundreds of pounds a year while enjoying a more comfortable and sustainable home. From an energy-saving perspective, double glazing lasts up to 25 years.

Having installed windows for over 30 years, we would recommend A- and B-rated windows as the minimum you should be looking for. C-rated windows might appear to be a compromise between budget friendliness and energy efficiency, but they simply aren’t efficient enough for us to recommend them. If you would like to discuss your needs with a member of our friendly team, we would be more than happy to offer you some advice. Please call us on 020 8648 0426 or email sales@sciwindows.co.uk