GLASS TYPES
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There are three types of glass that are available for household windows:
Standard clear glass
This glass was the first and only type to be installed in millions of houses throughout the years and is fast being replaced with more thermally efficient versions, such as Argon filled black swiss spacer bar or K Glass.
Low E (Emmisity) or K glass (more commonly called)
This improved glass (in comparison to Standard glass) has an increased environmental performance with less CO2 emissions and better thermal efficiency and nowadays it is compulsory (to comply with Building Regulations) to put Low E or K Glass into NEW houses.
Basically by using less heat to keep your home warm, less energy is needed – thus lowering the overall levels of greenhouse gases.
Pilkington K-Glass usually forms the inner pane of a double glazed unit, and has a special ‘low emissive’ (Low E) coating which is a good reflector of long wave radiation (heat). This allows less heat to escape through your windows, because it reflects the heat from fires and radiators back into your home.
At the same time Pilkington K-Glass lets the suns heat through your window contributing to its energy efficiency. This free heat from the sun is known as passive solar gain and Pilkington K-Glass offers the UK’s leading performance in this aspect.
So whilst offering positive benefits to the environment, this also has great benefits for the homeowner.
K Glass (low e) essentially allows heat from the sun into the room, but stops it leaving by reflecting the heat back in.
Using this glass in conjunction with warm edge black spacers and Argon gas , Double glazed units can become as effective as triple glazed units.
It is also good practice to try and replace windows in existing houses with Low E or K glass but this is not always practical. The reasons being that K glass has a slight tint to it and it will not match the rest of the property if the remaining windows have standard glass. But, you could upgrade all their windows to the more efficient K glass and benefit from reduced energy bills.
NB. Both of the above types of glass, both K and Standard, including patterned glass can come as toughened.
Toughened Glass
Toughened glass usually has a kite mark on it and is exactly what it is described as – toughened or tempered. It has been manufactured by controlled thermal or chemical treatments to increase its strength compared with normal glass. It will usually shatter into small fragments instead of sharp shards when broken, making it less likely to cause any injury if smashed.
It is a requirement of the Building Regulations that any pane of glass sitting between finished floor level and 800mm above that level in internal and external walls and partitions needs to be toughened. Also, between finished floor level and 1500mm above that level in a door or in a side panel, close to either edge of the door (300mm) also needs to have toughened glass installed. The reason is obvious; people are more likely to come into direct contact with glass at this level hence using toughened is a precautionary safety measure.
It would be true to say that glass units should be replaced like for like i.e. whatever glass is taken out should be replaced with the same. But it is perfectly acceptable to replace with upgraded options such as more thermally efficient glass.
You can get a copy of The Building Regulations 2000 - ‘Glazing - safety in relation to impact, opening and cleaning’ Approved Document N. This can be bought online at www.tso.co.uk for a fee or you can download for free on www.planningportal.gov.uk/wales/professionals/buildingregs/technicalguidance/bcglazingsafetypartn/bcapproveddocuments11.
If your glass has a kite mark on it, it is more likely to be toughened glass b
So in a nutshell you can get:
4mm Standard Clear Glass
4mm Obscure Glass (pattern glass)
4mm Standard Clear Glass Toughened Glass
4mm Obscure Glass Toughened (pattern glass)
4mm K Glass Clear
4mm Obscure K Glass (pattern glass)
4mm K and Toughened Glass Clear
4mm Obscure K and Toughened Glass (pattern glass)
Please also note that you get Leaded Glass and Geo Bar Glass
Leaded Glass - Diamond and Square
Georgian Bar and Astregal Bar
Pattern Obscure Glasses
There are different patterns of glass available and also be aware that Obscure Glass comes with different privacy levels; 5 being the highest and the most private and 1 being the lowest and the least private.
For all Glass Types from Pilkington, please Click here: Glass Types
Argon Filled Glass
There are also newer Argon filled Double Glazed units out there and you will find these units have black spacer bar and this is rubberised (they call it warm edged black swiss spacer bar). You do have the option to upgrade to this from the normal standard silver, gold or bronze standard spacer bar.
Argon is a colourless, odourless, non-flammable, non-reactive inert gas and is used to reduce the heat loss in sealed units by slowing down convection inside the air space. This gas is extremely cost efficient, and when used with softcoat glass gives you excellent thermal performances.
Argon gas increases the windows ability to insulate. Because the gas does not conduct heat as readily as air, it helps keep heat in during the winter and out in the summer