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Coming into effect on the 01st October 2010, (Document L)
of the
building regualtions are changing and we have to by law install
a minimum, approved Window Energy Rating
of 'C'.
This new law is applicable to every installer of double glazed
PVCu
(uPVC) window systems - period, no exemptions !
As you would expect from one of Birmingham's most established
manufacturers we are taking the lead and will only offer a choice
of
either A rated, or C rated window energy rating double glazed
windows.
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So what is a Window Energy Rating (WER)
?
The window energy rating is simply the objective
method used to assess the total energy performance
of a window; taking into account the materials used (including the PVCu
frame, glass and materials etc),
plus any possible air leakage via gaskets and joints and the solar gain
(energy from the sun), to determine
the energy rating which expresses the actual energy efficiency of the
product.
The determined value will place the double glazed window
product into a energy rated band from (A to G).
The rating compare standard size windows; thus providing a simple method
of comparing different
products from either the same supplier or, different suppliers. Most
people will be familiar with the energy
efficient labels showing such as A - G ratings on products such as white
goods, like Frodges, which
operate on the same principle and method as that for windows.
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What the Energy Rating BAND actually mean ?
When looking at the energy rating label, as well as which band
the
window falls in to - it is given a figure. In the label shown
(right) it is
band ‘C’ and the figure is -14. This means that the
window loses
14 KWh/m2/per year, (This is actual energy escaping via the window).
Hence, Band C is the proposed new Building Regulation minimum
requirement as from October 2010.
A house glazed with windows that meet current building regs,
i.e: a whole window U-value of 2.0W/m2 K or less, would be in
a
WER band of ‘E’, hence the energy lose through this
type of window
could cost £240 pa. Older type properties with single glazed
or narrow
cavity windows would be in lower bands losing even more energy
and
this could cost well in excess of £330 pa at today’s
energy costs.
This means in this example a householder could possibly save
around £170 pa simply by changing from a 'E' rated to a
'C' rated
energy window. Hence, it is well worth considering changing or
upgrading your timber, or existing PVCu double glazed windows.
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BFRC Rating Scale
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BFRC Rating KWh/m2/pa
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A
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0 or greater
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B
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-10 to < 0
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C
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-20 to < -10
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D
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-30 to < -20
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E
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-50 to < -30
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F
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-70 to < -50
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G
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Less than -70
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For further information on
BFRC ratings, click
here:
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Note: An ‘A’ rated energy window which has an Energy
Index figure of 0 or above, means
the window loses no energy and could actually allow solar energy into
the house therefore
achieving further savings.
The vast majority of installed ‘low e’ standard windows fitted
with 'Low E Glass' today only
equate to an 'E' rating on the WER scale.
How to move up the Window Energy Rating (WER)
scale ?
The energy rating label runs from A to G with band ‘E’ as
the lowest level permitted for replacement
windows under current (pre April 2010) Document 'L' of the building
regulations. This generally requires
a standard ‘Low E’ double glazed sealed unit.
‘C’ rated energy windows would generally require a
sealed unit with 'Low E' glass, Argon filled
and possibly warm edge spacer bar - this is the proposed minimum level
from October 2010.
‘B’ rated energy windows would generally require a
sealed unit with soft coat 'Low E' glass,
Argon filled and with warm edge spacer bar.
‘A’ rated energy windows would generally require a
sealed unit with soft coat 'Low E, low iron glass,
Argon and warm edge spacer bar.
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