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Window energy ratings explained

When looking for new windows, energy rating is usually a customers top concern. It may even be the first thing you check when looking at a product. But what do energy ratings mean for you, and what are the different types of rating? With this brief guide, we hope to give you a solid understanding of the different types of window energy ratings and how different levels affect your home.

What are window energy ratings

Window energy ratings are different from door ratings. Currently, there are three types of ratings, offered by three separate organisations. The BRFC, the British Standards Institute and Certass. All are officially recognised standards in the UK. They measure three factors that are combined to give an overall rating which indicates the energy efficiency of a product.

These independent bodies rate efficiency slightly differently but are are somewhat comparable, however. Generally speaking a grade of A or better from one organisation should indicate a better thermal performance than a B graded window from another organisation.

What’s measured?

When rating the energy value of windows these organisations measure 3 key values:

  • The U-value, which measures thermal transmittance, or heat conducted through the glass or the frame of the window.
  • The L-value is a measure of air leakage, more specifically heat that is being lost via escaping warm air.
  • Finally the g-value which measures heat gained. This is calculated by measuring the amount of solar energy transmitted through your glass.

What are the benefits of high energy ratings?

Better ratings equal better insulation for your home. This translates to you having to spend less on your heating bills which can save you large sums of money in the long run. Be careful though, whilst high energy ratings are great, in some cases a high g value can be negative, as this indicates that, though energy is retained its difficult to let hot air out when in the summer months.

At DGN we supply windows that are A+ rated by default, achieved through Liniars exceptional industry-leading multi-chambered frames. Meaning you get exceptional insulation for your money, every time. If you’re in need of new, highly efficient windows, get in touch, or use our Installer locator or start an online window quote tools to get started.