GUARDIAN GlassTime
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Light, energy and heat.............................................30
2.1Light..........................................................................................30
2.2
Solar energy.............................................................................31
2.3Heat..........................................................................................32
2.4
UV radiation.............................................................................33
2.5Photovoltaics...........................................................................33
Dream House, Moscow
SunGuard® HP Light Blue 62/52
Murray O‘Laoire Architects
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GUARDIAN GlassTime
The physical definitions of light,
energy and heat describe defined areas of the electromagnetic spectrum.
In this spectrum, UV radiation lies
between 300 and 380 mm (300
nm = 0.0000003 m), visible light
between 380 and 780 mm and
near IR between 780 and 2,500
mm. Heat is long wave radiation
in the far IR wavelength areas of
approx. 5,000 and 50,000 nm
(0.005 mm - 0.05 mm).
The area relevant to architectural
glass in connection with light and
solar energy falls within a 300 2,500 nm (0.0003 mm - 0.0025
mm) wavelength.
Longer wavelengths are termed
radar, micro and radio waves,
while shorter wavelengths are
known as x-ray and gamma radiation.
0.0003 - 0.0025
0
Wavelength [mm]
Range building glass
103
10-2
10-5 10-6
10-8
Wavelength [m]
10-10
10-12
Light, energy and heat
When light hits an object, the
object absorbs part of the energy spectrum. Glass, however,
transmits light, reflecting the rest
of the energy. Depending on
the nature of the object, certain
wavelengths are reflected and
others absorbed. The eye perceives the reflected colour as being the colour of the object.
Artificial lighting can result in
colour misinterpretation due to
missing wavelength ranges. A
well-known example is low-pressure sodium vapour lamps. Since
they lack blue, green and red
wavelengths, everything appears
in monochromatic yellow tones.
2.2 Solar energy
The radiation emitted by the sun
that strikes the earth is called solar energy. This wavelength range
has been defined through international standardisation (EN 410)
as ranging from 300 to 2,500 nm
and includes the UV, visible light
and near infrared light categories.
The worldwide accredited global
radiation distribution curve (acc.
to C.I.E., Publication No. 20)
shows the intensity of total solar
radiation in its respective wave
ranges. Fifty-two per cent of
these wavelengths are visible and
forty-eight per cent are invisible.
Total radiation
100 %
visible
55 %
heat
41 %
ClimaGuard®
Premium
Microwave
Radio
Ultraviolet
Infrared
visible light
X-ray
Hard gamma
radiation
Wave spectrum
2.1Light
The small area of the solar spectrum that can be seen by the human eye is called (visible) light.
Unbroken (visible) light hitting the
human eye is perceived as white
light. It is, however, composed of
a light spectrum where the various wavelengths – each representing a defined energy – flow
into each other:
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Colour
Wavelength [nm]
violet
380 - 420
blue
420 - 490
green
490 - 575
yellow
575 - 585
orange
585 - 650
red
650 - 780
Relative radiation intensity [%]
90
Visible
­radiation
Heat
radiation
Total
radiation
80
70
60
conv. Insula­
ting glass
75 %
79 %
30 %
66 %
54 %
73 %
Permeability of ClimaGuard® Premium and conv.
insulating glass, based on the intensity distribution of the solar spectrum.
Energy distribution acc. to DIN EN 410
(Air Mass 1.0)
50
40
30
100
90
80
70
60
50
40
30
20
20
10
10
0
300
500
700
Relative sensitivity of the naked eye [%]
UV
4%
100
0
900 1100 1300 1500 1700 1900 2100 2300 2500
ClimaGuard® Premium
Sensitivity of the naked eye
Wavelength [nm]
Conventional insulating glass
Solar spectrum
Global radiation distribution curve (C.I.E., Publication No. 20)
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GUARDIAN GlassTime
The shorter the wave length, the
more energy is transported. That
means that there is a considerable quantity of energy in the
visible portion of the radiation.
Therefore, light and energy cannot be separated from each other. This is a critical aspect in using
and improving architectural glass.
Important properties that are
critical for characterising the nature of architectural glass such
as solar energy transmission,
reflection and absorption and
total energy transmittance, can
be derived from the solar energy
in the global radiation wavelength range (300 - 2,500 nm)
and its interactions with glass
(Þ Chapter 5.4).
2.3Heat
Its interaction with heat defines
the insulation characteristics of
architectural glass and is influenced by heat radiation, heat
conduction and convection.
The Ug value – the coefficient of
heat conductivity – is the fundamental characteristic for judging
the glass construction material’s heat insulation capability
(Þ Chapter 3.5).
2.4 UV radiation
The wave range between 315
and 380 nm is known as UV-A.
If If the intensity is too great, this
radiation has not only a more or
less destructive impact on the
skin but also on many other elements (paintings, sealing material, etc.).
Normal insulating glass with 2
panes reduces this radiation by
more than 50 %, and when combined with laminated safety glass,
the radiation is almost completely
filtered out (Þ Chapter 7.4).
2.5Photovoltaics
Another interesting range of the
light spectrum falls between approx. 500 and 1,000 nm, where
certain semiconductors are able
to generate electric current from
solar radiation. The most popular
forms are various silicon crystals
which are to be found packed
between panes of glass, in numerous façade balustrades and
on roofs.
Transmission, QE [%]
Heat or heat radiation are a wavelength range that is not part of
the solar spectrum. Heat radiation has far longer wavelengths
and is to be found in the far infrared range. In the European
standard EN 673, this range is
defined as being between 5,000
and 50,000 nm.
Light, energy and heat
Developments in recent years
continue to expand this techno­
logy through other n-semiconductors like indium sulphide
which are mounted directly on
base glass on a large scale using the magnetron process.
­GUARDIAN offers a wide range
of these types of coatings for
float glass, including special,
light-deflecting and transmission
optimising ornamental glass.
100
EcoGuard®
90
Clear float
glass
80
70
QE c-Si
60
50
200
400
600
800
1000
1200
Wavelength [nm]
EcoGuard® smooth or structured glasses enable significantly higher energy transmission than normal clear glass over the wavelength range, a decisively important factor
fpr photovoltaic modules.
EcoGuard® pattern transmission vs. clear glass
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