Glazed windows can come in various types, shapes and sizes, but their efficiency will ultimately be determined by how well they stop heat from passing through, how much sunlight can penetrate the glass and how much air they let escape. Whether you’re looking at secondary glazing or double and triple-glazing, upgrading your windows could go a long way in reducing your spending on energy bills.
When looking to upgrade your windows, there are three main things to keep in mind. The glass should be low emissivity—Low-E—with a coating of metal oxide on one of the internal panes. The gaps between sheets of glass should contain gases such as krypton, xenon or argon in order to make them efficient. Lastly, pane spacers—which keep the various sheets of glass apart—should contain little or no metal, these are often known as ‘warm edge’ spacers.
Glazed windows will be available in a variety of frames in all the existing energy ratings. The type you choose will largely depend on your needs and budget—uPVC frames last a long time and may be recycled, wood frames have a lower environmental impact, aluminum frames are also long-lasting and composite frames have a timber frame covered in plastic (or aluminium) making them a low maintenance and weatherproof solution.
A window’s energy rating is assessed by how well it can retain heat. According to the British Fenestration Rating Council (BFRC), energy-efficient windows and doors have a rating of ‘A++’. A ‘C’ rating is required to satisfy building regulations for windows, while an ‘E’ rating (the lowest grade) is required to meet building regulations for doors. Some exceptions to these rules may be historic buildings or conservation areas. An additional parameter that you should look out for is the U-value; it measures how well heat can pass through a certain material. Low U-values mean the material lets less heat pass through it—indicating better insulation levels. Considering both the energy rating and the U-value of windows is crucial when deciding which types of glazed windows to install in your home.
Did you know?
Replacing single-glazed windows with energy efficient double-glazing may save you around £135 on energy bills per year. Source: The Green Age
See also: Glazed Windows