What makes windows and doors energy efficient

Energy efficiency – which ratings make a difference

It probably comes as no surprise that one of the most important considerations quoted by consumers when choosing new windows and doors is energy efficiency.

Numbers matter, and there are probably two key indicators of window energy efficiency. We’ll go into those in more detail later, but the thing that will probably make the most difference to you is how your home actually feels.

Getting modern windows and doors fitted will make your house cosier, eliminating draughts, and improving thermal efficiency – both of which will help you really make the most of your heating – and lower your energy bills.

To help you make the right choices though, there are two main measures of thermal efficiency with windows and doors. Don’t panic if you can’t always get the highest score from your choices, as you’ll also have other considerations such as style, and budget to think about. Whatever your choice though, it’s a fair bet you’ll be making an improvement on your existing windows.

U-Values

U-value is a unit of measurement, in W/m²K (Watts per metre square kelvin), used to measure the transference of heat through a structure. It’s used to determine how quickly heat can escape through a material. The lower the U-value of a material, the slower the heat will transmit through the material, meaning the material has high thermal insulation properties.

Generally speaking if you can hit a U-Value of 1.5 W/m²K you are on the right path. Get below 1.0 W/m²K and you are really cooking, so to speak!

Window and Door Energy Ratings

Window and door energy ratings (WERs and DERs) are a useful way for homeowners to determine energy efficiency. They identify how well products perform at:

• Keeping out draughts.
• Adding warmth through solar gain.
• Preventing heat loss.

The British Fenestration Rating Council (BFRC) rating system is a really simple graphic guide for consumers. Any rating of A or above means that those windows and doors are really up to the task. 

All in all, a lot depends on the exact specification of the windows you want, and the type of glazing specified but get the specifications right and you’ll be impressed at how well you can manage your energy bills and how much cosier you can feel at home.