Consumers, specifiers and legislators 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 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.
Windows are crucial to ensuring that our homes are warm, light and above all, energy efficient. However, choosing the windows that are best suited to you has been a difficult task with so many conflicting claims by suppliers. With the introduction of the window energy rating scheme it is now possible to easily compare the performance of products and ensure you will get the right windows for you and your home.
• Installing energy efficient windows could reduce your heating bills by around £90 a year
• If everyone in the UK installed energy efficient windows it could save up to £660 million a year
• You could save up to 620kg of CO2 - that’s three double decker buses full of CO2 each year
• If everyone in the UK installed energy efficient windows it could save up to 4.5million tonnes of CO2 per year
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. simulation of the product to European Standards and the use of climate data and building models. This gives a single figure that can be used to compare the energy performance of a window simply and quickly.
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