Windows Energy Ratings Easily Explained

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It is estimated that up to 20% of your home’s energy is lost via the windows, giving true meaning to the phrase ‘throwing money out the window’. Understanding your window energy ratings can stop you getting caught out and landed with a hefty energy bill. In this guide, we’ll be helping you get smart about energy ratings, and covering how they can help you and your home.

 

What are Window Energy Ratings?

Window Energy Ratings (WER) is a system to determine how energy efficient your windows are; in other words, how effective they are at gaining and retaining heat. Similar ranking systems are found on electrical appliances and lightbulbs, with a ratings ranging from G – A+ (lowest energy efficiency to highest). When ratings are applied, they take into account the whole of the window – such as type of glass, design, and frame – and are not related to one sole component.

These ratings are calculated by using a formula that incorporates several considerations, including how well the window retains heat, the U-value, and the amount of solar energy that can pass through the glass.

 

Window Energy Ratings Explained

WER labels typically consist of a rainbow display of the 7 available energy ratings, and will highlight the rating that has been given to that particular window. Ratings D – G are awarded to lower quality windows that have reduced energy efficiency. A + is given to windows with the highest thermal efficiency. Colours applied to each rating will differ depending on the rating scheme body that has rated that specific window.

Some labels will display the Energy Index which describes the Kilowatt Hours per square metre per year. The higher this number the better; positive numbers mean energy is being gained.

Since October 2010, all windows being installed must have at least a C rating. Companies, such as Abbey Glass, that are registered with a Competent Persons scheme will ensure that all windows installed will comply with Building Regulations.

 

What type of Window should you choose?

One technique to make your windows more energy efficient is to add more layers of glass. This can be achieved by investing in double and triple glazing, which adds extra insulative layers of air or inert gas in between the glass layers to boost thermal efficiency.

Low-emissivity coatings are now standard practice under building regulations and help prevent heat from escaping by reflecting it back into the home. Investing in these types of glass can reap rewards in the future by increasing the Window Energy Rating and saving you money on energy bills.

 

Is Installation Important?

Skilled installation of the window is vital to ensure decent window performance. A poorly installed product will be a hindrance to its effectiveness and energy efficiency, so make sure you get specialists on the job. The team at Abbey Glass have over 40 years’ experience as professional glaziers, both crafting and installing numerous energy efficient glass products for homes and businesses alike.

 

Offering free quotations and a quick turnaround on all jobs, Abbey Glass should be your first port of call for any glazing job.

We provide double and triple glazing, along with glass replacement, glass cutting and crafting of multiple glass products. Get in touch today to find out how we can help you.

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Abbey Glass fully understands that without our customers we wouldn’t be a business. This means we ensure that we treat every customer as we would like to be treated ourselves.

We always try our best to meet your needs by offering help and advice on our complete range of glass and glazing materials. Due to our many years in the glass and glazing industry, we have developed knowledge, expertise and fully understand what our customers’ needs are. We apply this in all aspects of our work so that we are able to answer any customer enquiry and complete any job you may have.

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Recent News & Guides

Excellent
Abbey Glass4.6
Based on 144 reviews
Dave Hawkes
1 week ago
What a great company prices very comparable and the guys who do the work are very caring and do the job with perfect results Thank you
Peter Bayliss
3 weeks ago
Only a simple thing , needed some replacement glass for our greenhouse. Quick, cheerful and helpful service, all glass bubble wrapped and carried the glass to our car. Highly recommended!
James Bonham
4 weeks ago
Great experience with Abbey Glass. We had a sticking Bifold door, contacted them on Tuesday, they came at 9.00 on Wednesday - bang on time. They fixed the problem, what is more despite being out of guarantee - they did this free of charge. I wish all companies were like Abbey Glass, they are a credit to Sheffield.
James Raze
2 months ago
Really good firm, helped me out massively and very quickly as well!
Alan Pugh
3 months ago
Very helpful, and give you a fixed price 😁
Millie Middleton
3 months ago
Mariam Rashid
4 months ago
really quick, efficient and professional. left the place so tidy and the new laminated safety panel windows look great
Michael McFarlane
4 months ago
Quick , efficient service. A job well done. Thank you.
Brian Betts
4 months ago
Highly recommended - fantastic customer service
Gary Rossiter
4 months ago
Abbey Glass - used them a couple of times. Always fantastic!!!
Carolyn Snowden
4 months ago
Local company so a quick response to queries and keeping money & employment in the community. Customer care and service very good. I would recommend this company for double glazing and external doors as I am more than satisfied with my installations
Bronwen White
4 months ago
Prompt, efficient and cheerful service
Richard Thomas
5 months ago
Abbey Glass provided a first class service and the installation of a replacement panel carried out professionally.
Helen Dean
5 months ago
Excellent service. Very helpful and polite staff. Quick service and very good quality product. Would definitely recommend and use again. Thank you.
Dave Redman
5 months ago
The team were overall excellent. They were cheerful, efficient and did a very good job on replacing double glazed windows. They tidied up and took the rubbish away at the end and gave us some useful advice. We would recommend them to our friends
John Gittins
5 months ago
Just had 6 blown sealed units replaced this morning, Alan and his mate were in and out in no time no mess very cheery and efficient service would definitely recommend Abbey Glass.
Miles Davidson
5 months ago
Prompt & courteous. Glass well packaged, helped me load the car. Thanks 👍
Steve Platts
5 months ago
Helpful and friendly staff, great parking and small job carried out quickly with excellent results. Would definitely recommend!
Basharat Khan
5 months ago
Excellent service, and very generous .
Linda Goodare
5 months ago
Very quick efficient service and reasonably priced.They replaced 2 misted glass units and fixed an opening catch.On time and gave advice on hinges of units.Very good service and excellent service.Highly recommended.
Roger Lasko
5 months ago
Many thanks for being so helpful when I came in last Friday for help with my 'leaded' glazing units. You took the time to understand what the problem was, then sorted it for me. Couldn't ask for more.
Deborah Doane
5 months ago
great service friendly efficient work men
Sam Clowes
6 months ago
Great Quick Service. Staff were friendly, knowledgeable and super helpful
Viviane Ferraz
6 months ago
We have been recommended Abbey Glass by a friend who have used their services a few times and we had a great experience. With us it wasn't different, they were very professional and reliable! We will definetely be using their services whenever we need again! Thank you so much Abbey Glass!
Katy Ferris
6 months ago
Excellent service from the first phone call to the quote and then the fitting and all done within 2 weeks - I would wholeheartedly recommend them - for window repairs, saved money compared to other companies that wanted to replace whole windows. The team that come out - Alan, Mick and Mikey were brilliant!! - only wish we had booked them years before. We will only think of Abbey Glass in future for such jobs. Thanks Updated January 2026 - had a problem with window drainage and Alan and Mick came within a week and sorted the problem out - free of charge - pleased with the service. Will definitely use this company again.

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