Ordinary Glass Has Very High Emissivity

Ordinary glass has very high emissivity – ie it emits a lot of thermal energy – not ideal if you're trying to stop the warmth escaping from your home through the windows. Low-E glass, also known as "energy efficient glass" or "energy saving glass", "fire resistance glass". But what exactly is low e glass, and when should you specify it for your own windows? The "e" in low e glass stands for "emissivity" which is a measure of how much heat energy a material emits. Low e glass has been treated by depositing a very thin layer of either tin oxide or silver onto the surface of the glass, to reduce the amount of heat it emits. Nothing's perfect of course, and low e glass has a downside too: It costs more than ordinary glass. There is another use for low-e glass, structural glass: By coating the other side of the glass, you can keep heat out just as effectively – that could be extremely useful in a conservatory for example, helping to stop the room overheating when the sun shines, without having to fit expensive blinds which also block your view of the sky. If you're buying coated glass to prevent heat loss, it can save you several thousand pounds off your bills over 20 years, so you should be able to get a return on your investment if you plan to stay in your home for the long term – but if you are doing up your house with a view to selling it within a few years, you probably won't get your money back before you sell. In conclusion, Low-E glass is a very interesting technology that has the potential to save you a lot of money on your bills, but the extra cost may only be worthwhile if you plan to stay in your property for a long time. Source: glasszng