Energy Efficient Windows
How does the Window Energy rating system work?
The system rates energy efficiency of windows from A to G, with A the highest, just as you see on white goods such as fridges, freezers and washing machines.
What are the minimum requirements?
The minimum requirement for replacement windows is E and, for windows in new extensions, D.
Why has the window energy rating system been introduced? Mainly that some don't consider U values a comprehensive enough measure of thermal efficiency. Consumers often don't understand U values, but many are familiar with A-to-G energy efficiency ratings as used in white goods.
What measure does the window energy rating system use?
The window energy rating system measures kilowatt-hours per square metre per year (kWh/m2/yr) and represents the flow of energy across the whole window. If the rating is positive, it means the window is actually a net contributor of energy. This table shows the value for each letter on the scale: |
