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From energy-saving coatings to self-cleaning panes, there’s
plenty to choose from when specifying your home’s glazing, says Chris Bates.
Glazing has come on leaps and bounds in recent years.
There’s a product out there to suit almost any application. But with so much
choice available, how can you go about specifying the right product? In some
cases, the decision is simple – safety glass is an essential for stair
balustrades, for example. In others, you’ll need to weigh up which option is
best suited to the lifestyle you want your new home to deliver.
Comfort & efficiency
For most homeowners, saving energy and keeping running cost
down is the basic starting point when specifying glazing. The importance of
energy efficiency is reflected in Building Regs, too, which require a minimum
‘C’ window energy rating (WER) for all new units.
All efficient glazing is referred to as ‘low emissivity’
(Low-E), but there are subtle differences between products. Some feature a
‘soft’ thermal coating that favours heat retention and offers low U-values.
These include Pilkington’s Optitherm and Saint Gobain’s Planitherm. Others
feature a ‘hard’ coating that, while still providing good heat retention, puts
more emphasis on solar gain (g-values). Pilkington’s K glass falls into this
category. In our mild climate, there’s relatively little to choose between soft
and hard coats. For that reason, the WER system considers both U-values and
g-values, so A to C grades can be achieved with either type of Low-E glass. But
there is choice within each category. As well as the standard K Glass, for
example, there are two additional types. The S version offers better U-value
but poor g-value, while the OW spec matches the standard U-value but gives a
clearer glass and a slightly better g-value. On a typical double glazed unit,
the inner pane carries the Low-E coating (on the cavity side). The outer pane
can either be of clear glass to allow the maximum possible amount of daylight
to filter through, or could be treated with a solar control or other type of
coating. The gap between the panes is filled with gas (argon is most
economical, krypton more efficient) or fitted with warm-edge spacer bar – or
both for maximum heat retention.
Minimal maintenance
Washing down windows can be a real chore, especially if your
new home features vast swathes of glazing or hard-to-reach features such as
skylights. You can take a lot of the effort out of maintenance by specifying
self-cleaning glass, such as Saint Gobain’s Bioclean or Pilkington’s Activ. Its
external coating uses UV rays from daylight to break down organic dirt and
prevent other types adhering to the glass. The coating also causes rainwater to
‘sheet’ down the glass rather than forming droplets, giving the whole pane a
natural wash. Self-cleaning glass won’t take all the legwork out of
maintenance, but will mean you can wash windows less frequently and should make
the job quicker, too.
Safe and Secure
If you’re keen to provide the best possible protection for
your home, laminated security glass could be a wise investment. It’s made up of
sheets of glass held together with clear plastic film – in the event of a
breakage, the fragments adhere to the film to slow or even prevent entry.
Simpler laminated products – perhaps using just one or two films – can also be
used as safety glass.
Toughened glass is more commonly specified for applications
where safety is paramount (such as for stair or balcony balustrades). It’s heat
treated during manufacture to produce a product around five times stronger than
normal glass and, in the event that it does break, shatters into tiny fragments
with dulled edges.
Noise reduction
New double glazed units provide a measure of in-built sound
insulation via the draught proofing. But if you’re building near a busy road or
railway line, or you want to introduce some sound deadening for internal glazed
partitions, you can upgrade to acoustic glass. This is a laminated product,
with two sheets of glass sandwiching a sound-reducing inter-layer. You can
cancel out even more noise by opting for different thicknesses of glass in
double-glazed units.
Light and privacy
Maximise natural light levels internally is, understandably,
a major goal for many self builders. The first step is to use glass for the
outer pane of your home’s double or triple glazing. For even better views you
can switch to extra-clear, low-iron products such as Saint Gobain’s Diamant,
Which is suitable for everything from windows and external doors to internal partitions
and stair balustrades. Bear in mind,
though, that allowing too much daylight – and its associated UV rays – into
your home can lead to overheating in summer. That’s where solar control glass
comes in. Pilkington’s Optifloat Tint reduces both heat and light penetration,
which can be desirable in certain areas of contemporary glass-filled homes
where privacy is important. At the other end of the scale, the company’s
Suncool range filters out solar heat while still allowing high levels of
natural light pass through.
Hope you found this artical helpful when talking about glass and U-values. Please check out some of the pages below from our website for more useful information:
Glass Options: http://www.duration.co.uk/GlassOptions.asp
Window Energy Ratings:
http://www.duration.co.uk/WindowEnergyRatings.asp
Aluminium Windows: http://www.duration.co.uk/AluminiumWindows.asp
