Figures from The Energy Saving Trust reported that as much as 20% of a home’s heat loss occurs through its windows and doors. This increases the household’s fuel bills and its carbon footprint. Since energy prices are permanently on the rise it makes sense for homeowners to make their property as thermally efficient as possible.
The thermal efficiency of a window is independently verified by the British Fenestration Rating Council (BFRC); an organisation formed to develop an energy rating system specific to windows and doors. The resulting system shares similarities with those used on domestic appliances like fridges, freezers and washing machines.
The BFRC label clearly indicates a window’s energy rating – A+ being the highest, G, the lowest.
Some period properties (such as Victorian and Georgian homes) may still have the original sash windows. These are notoriously energy-inefficient (especially by today’s standards) thanks to single-glazing, failing frames and general wear and tear (remember that in many cases these windows may be more than a hundred years’ old!)
In contrast, windows fitted today boast many mod-cons that ensure they are as thermally efficient as possible. For example:
- The space between two (double glazed) panes is filled with argon gas. This has a 34% lower thermal conductivity to air.
- The spacers (which are used to keep the glass panes apart) are made using a non-conductive polymer plastic. This completely eliminates heat transfer.
- The glass has a metallic coating which reflects heat back into the room whilst allowing passive solar heat gain (i.e. heat from the sun) to pass through.
When combined, these elements give the window its final rating, which is independently verified by the BFRC.
what is a rated double glazing
An A-Rated window is one of the highest performing windows on the market in terms of energy efficiency, heat retention and overall performance. A-Rated windows help reduce energy bills and can prevent heat from escaping your home. Generally, the higher a window’s rating, the more it will cost. However, improvements in window technology means that reputable companies will now offer A+ rated windows as standard. Just remember that over the lifetime of a window, the initial outlay should be more than recouped in reduced energy bills (not to mention the fact that your property will be warmer, quieter, and more comfortable).
Find out more about A+ Rated windows offered by Stormclad here.
What U value is an A-rated window?
‘A’ rated windows have a U-value of around 1.4. A U-value is the rate of transfer of heat through a structure, divided by the difference in temperature throughout that structure. The better insulation properties a structure has, the smaller the U-value will be.