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A-Rated Windows

What are Window Energy Rating (WER)?

Consumers are increasingly focusing on the energy efficiency of building products to reduce the amount of carbon emissions. To respond to the challenge of raised expectations, the window industry must provide energy efficiency information that is easily understood and can be used to compare fenestration products.

The simple U value does not fulfill these requirements because it only focuses on the heat loss from the window and takes no account of the solar heat gain that windows are responsible for and how they can improve the overall energy efficiency of the house.

In the past, selecting energy efficient windows has been difficult due to the lack of independent and validated information. There is a need for a method that is both easy to understand and independent. The British Fenestration Rating Council (BFRC), in conjunction with the UK glazing industry and European partners has designed a window rating system to meet this need for simple and accurate information. This provides third party certification for the total thermal performance of windows using a ‘fair, accurate and credible’ assessment scheme.

The A-G Rating Scale

Windows are rated using the familiar A to G scale on the basis of their total energy efficiency, where an A-rated window is more energy efficient than a G-rated window. Consumers and specifiers can quickly and easily choose the most suitable window for their needs, government inspectors and agencies can quickly and easily see if the window meets the legal requirements and energy agencies can see if the window meets their criteria.

How is it calculated?

The Window Energy rating assesses the whole window energy performance and covers the frame material, the frame design, the glass type and all the other components that make up the window. The rating is carried out by computer.

What are the benefits?

• The method allows ease of recognition by using the all familiar charts and labels
• Widens choice by allowing people to choose better performing products for there own property
• Allows people to contribute to the overall reduction in greenhouse gases
• Energy rated windows could reduce heating and fuel costs by up to 10%
• Rising fuel and heating costs reduces the payback time on fitting new energy efficient windows
• 'C' Rated windows have a 94% lower heat loss than an 'E' rated window
• 'A' rated windows can have a 'Zero' energy loss of a years cycle and can even add energy back into a property by solar gain