Understanding The Key Glass Performance Ratings

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Whether you are looking to sell your home or merely sprucing it up, one of the more popular upgrades you can do is changing the doors and windows. They are proven to increase the value (and curb appeal) of any home.

You know you want an aluminium frame with a four leaf fold, but seeing the sheer amount of options available, your eyes glaze over. What’s the difference between Low-e and tinted glass? Why is one type of glass considered ‘A-rated’ and another ‘tempered’? To make a sensible choice, you’ll need a crash course in the terminology used in identifying and recommending glass.

But first, let’s address two common defects of old door and windows:-

  • Potential UV damage:- If your windows and doors are old (over 50years), I bet you have a faded sofa or some discoloured curtains in that room. The sun’s harsh ultraviolet rays can cause things to fade; your hardwood floors,the carpet, photographs can be all damaged by prolonged exposure to the sun.
  • Old windows and patio doors are also notorious for a high degree of leakage. These ‘gaps’ allow heat to escape, and let the cooler air in. Leakage is often linked to one of three things:
    • Degradation of the rubber that surrounds the glass.
    • Improper assembly of the frame.
    • Clogged weep holes.

Over time, leakage will become a source of irritation especially when you’re faced with a much higher energy bill. Face it, old windows can be a drain on your pocket. So, what’s the next step?

Bombarded with glazing options, energy ratings, different treatments, you are already overwhelmed. All you have to do is understand four key features and what they mean will help you make a smarter choice.

Note that if this is a replacement project, you may need to double check that you don’t need planning permission. If you live in a conservation area and there are regulations about what you can do with the property, you just might. So, double check with the council.

Important factors to evaluate when choosing glass

The most important factors to evaluate when picking glass for your windows and doors are:

  • Air Leakage – This refers to the amount air that can flow through the window; tiny cracks in the window/door assembly allow air to pass through ‘solid’ glass. The amount of air leakage that occurs impacts how warm or cool the room gets. Lower air leakage means the glass is more air-tight.
  • Heat Transmittance (U-Value): The glass (in windows or doors) experiences a wide range of temperatures daily causing a lot of heat gain and loss. The amount it lets in, via conduction, is generally described as its U-value. Look for a lower U-Value as this means the glass has greater to heat flow i.e. a better insulating value.
  • Solar Heat Gain Coefficient (SHGC) – This describes the amount of solar/thermal energy that passes through the glass. A lower value SHGC indicates that less solar heat enters the room, making it effective for keeping out heat in the summer. Note that solar heat gain can be influenced by the glazing, number of panes, and any treatment done to the glass.
  • Visible Transmittance (VT) – This indicates the amount of visible light that is transmitted through the glass. Lower VT means less visible light gets through; this value is best considered if the window/door is south facing and receives a lot of direct sunlight.

There are a bunch of other factors you may consider such as e-coating, tinting, lamination, surface treatment etc.; but these four are the most important. To make sure you have the most efficient type of glass, always insist on using glass that is BF-approved.

At SRL Limited, we pride ourselves in educating our customers and working with them to get their perfect home. For more information on how your house can become even more energy-efficient, check out the rest of our site or give us a call.

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