Energy efficiency - Facts
The facts about saving energy and reducing fuel cost in your home
We all want to help the environment and make our homes more energy efficient – it’s just commonsense.
But how do you compare different kinds of double glazing – and how well they save energy? Read on and see.
How does the Window Energy Rating system work?
It rates the energy efficiency of windows from A to G, with A the highest - just as you may have noticed on fridges, freezers and washing machines.
The system measures the whole window, glass and frame. It combines three factors that affect energy performance: heat loss, solar heat gain and heat loss through air infiltration.
Then it measures kilowatt-hours per square metre per year (kWh/m2/yr). This shows you the flow of energy across the whole window. A positive rating means the window is actually a net contributor of energy (good). This table shows the value for each letter on the scale:
| kWh/m2/yr | A-G scale |
| ÿ0 | A |
| -10 to <0 | B |
| -20 to <-10 | C |
| -30 to <-20 | D |
| -50 to <-30 | E |
| -70 to <-50 | F |
| <-70 | G |
What are the minimum requirements?
The minimum requirement for replacement windows is E and, for windows in new extensions, D.
What does this mean in terms of you saving energy and reducing fuel costs?
Well, a single glazed window loses energy at a rate of -198 kWh/m2/yr. So if you trade up from single glazing to a B-rated window will save at least 190kW/m2/year.
The average house, with eight square metres of glass, will save 1,520kW per year. Assuming electricity costs around 11p per kWh, this would mean a saving of £167 per year. Worth thinking about
How does Everest double glazing compare to other windows?
Our double glazing is at the forefront of energy efficiency developments.
Our uPVC casement windows use low-emissivity glass as standard and achieve a ‘B-rated’ window energy rating and are certified by the Energy Saving Trust.
Our “A-rated” energy efficient windows are the most energy-efficient and the most environmentally friendly double glazing you can find.
Our “A-rated” energy efficient windows uPVC casement windows are also certified by the Energy Saving Trust, too. We were the first to distribute “A-rated” energy efficient windows nationally.
More Information
