In these volatile and wuthering Atlantic islands, everybody knows what double glazing is, but how many of us buy windows with no idea how one differs from another?
Thanks to improvements in EU building codes, glazing has to comply with a range of statutes as outlined at http://www.double-glazing-info.com/Benefits-and-regulations/Building-regulations-and-quality-standards. However, those requirements do not tell us about the energy and economic value of one window over another.
Most people know that the number of panes, the thickness of the glass, the depth of the void and special coatings make some difference. Surprisingly, none of these factors should concern us too much as they only a small difference and we can take for granted that modern insulated glass units (IGUs) fall within the safe range. Buyers should be far more aware of two other important details.
Ideally, panes should be 16 to 19 mm apart, but what is between them? In fact, IGU voids often contain just air, although moisture is removed from this air to prevent condensation between the panes. Air is a reasonably good insulator, but it’s not a great one. Better options include inert gases, usually argon – krypton and xenon are better but expensive – or a vacuum. Argon’s thermal conductivity is just 67 per cent that of air, and krypton’s is less than 40 per cent.
Voids can contain other gases, such as sulphur hexafluoride. This is also sound-insulating, making it a valuable addition if your home overlooks a motorway, railway or airport.
Frames, seals and spacers
Metal frames allow heat to bypass your glazing, but even wood and PVC conduct. The spacer holding the frames apart is a critical component. Historically, spacers have often been made of metal for durability, perhaps with some fibrous material or polyurethane foam, but often it’s inadequate. Better insulated materials are available, but this is definitely something to research. Quality spacers are also important for sound insulation.
The best guarantee is choosing a reputable company in the first place. If you’re looking for uPVC windows or extensions to your home like Conservatories Gloucester or anywhere else in the Cotswolds, then search for businesses that have a good reputation in your area and come recommended to you.
If you ever see condensation inside your units, it’s a reliable sign that leakage has occurred at some point. Companies exist that will refill voids and repair seals, but most will tell you it’s more economical to replace the unit altogether.