Tài liệu Lighting with Artificial Light 02 docx

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Education in Germany
39 million people of all ages in
Germany are enrolled at schools,
universities and other educational
establishments. 20 million chil-
dren, pupils and students attend
the country‘s more than 100,000
kindergartens, schools and universi-
ties. Nearly half of these educational
establishments are day care centres,
catering for more than five million
children. The smallest group of edu-
cational establishments - the coun-
try‘s 355 universities - are attended
by over 12.8 million students.
Almost exactly as many people
are in further education: 19 million
Germans and foreign nationals in
Germany regularly attend courses
at adult education centres, upgrade
their occupational qualifications
at chambers of industry and com-
merce or pursue courses of study at
open universities.
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12
Kindergardens, schools and universities
day care centres 48,203
nursery and primary schools 20,695
secondary schools 12,079
vocational schools 11,372
other schools 8,667
universities 355
(figures indicate actual number of establishments)
Adults in further education at
state-funded adult education centres 9,392
other adult education centres 8,534
chambers of industry and commerce 596
chambers of handicrafts 278
distance-learning institutes 121
(figures indicate numbers of persons in thousands)
Children, pupils and students at
kindergartens and crèches 5,169
nursery and primary schools 3,600
secondary schools 6,449
vocational schools 2,773
universities 1,868
(figures indicate numbers of persons in thousands)
All data taken from the basic and structural statistics
(Grund- und Strukturdaten) published by the Federal
Ministry for Education and Research and the school sta-
tistics compiled by the German Federal Statistical Office
4
Lighting and human needs
Reflections on paper
Especially where glossy
materials are used, poorly
shielded luminaires cast
disturbing reflections
(Fig.
21)
. Well shielded lumi-
naires avoid this effect and
permit all materials to be
studied with ease
(Fig. 20)
.
W
e experience our
environment first
and foremost
through our eyes. 80
percent of the sensory im-
pressions we receive are
visual. Too much or too lit-
tle light, glare or distorted
colours impact on what
we perceive, distract our
attention and cause visual
fatigue.
In all areas of life and
throughout the working
world, good and appro-
priate lighting is a prime
requirement for enabling
us to see clearly, enjoy a
sense of wellbeing, per-
form concentrated fatigue-
free work and perceive
and interpret important
information and our sur-
roundings correctly. This
calls for good, profes-
sional lighting design.
Below are some of the key
factors that need to be
considered for good light-
ing design.
Illuminance
In daylight, the illuminance
of an illuminated surface is
between 10,000 lux (over-
cast sky) and 100,000 lux
(bright sunlight). Indoors,
we need to make do with
much less light. For writing
and reading, it is generally
enough if artificial lighting
provides 500 lux illumi-
nance; for drawing or other
visually demanding tasks,
illuminance should be at
least 750 lux. For more
information about illumi-
nance values and the re-
quirements of the relevant
industrial standard, DIN
EN 12464-1, see page 46.
The values set out in the
standard, however, are
minimum requirements.
Most people find a higher
level of illuminance more
agreeable and more moti-
vating. In winter especially,
when the levels of daylight
entering a room are lower,
more light is needed to
avoid fatigue and loss of
concentration.
Glare
Glare is one of the most
disturbing side-effects
of lighting. Direct glare
caused by marked contrast
differences between very
bright and very dark sur-
faces or due to unshielded
lamps in our line of vision
place a strain on our eyes
and lead to fatigue and
mistakes through loss of
concentration. To avoid di-
rect glare from lamps, care
should be taken to select
only luminaires which are
suitable for workplace
lighting. Direct glare limita-
tion is indicated by a UGR
index, which should be 19
(Fig. 13).
Equally unpleasant and
fatiguing for the eye are
frequent switches between
bright and dark room zones,
e.g. between window and
desktop
(Fig. 15)
. This
can be avoided by correct
positioning of desks, light-
control blinds and good
lighting
(Fig. 14).
Shadowing
Where there is light, there is
also shadow. To ensure that
shadows do not impede our
view when writing, the light
should fall - for a right-handed
person - from the left
(Fig. 16)
.
If the light comes from the
right, we write in the shadow
of our own hand
(Fig. 17)
Brightness distribution
When we are in a room,
our gaze incessantly
switches from near (desk-
top) to far (walls). Where
there are marked differenc-
es in brightness between
these two zones, our eyes
face the constant need
to re-adapt and thus get
tired more quickly. Visual
performance and sense of
wellbeing diminish.
Where the differences
in brightness are not
marked enough, however,
the room makes a mo-
notonous impression. It is
recommended here that
desktop luminance should
not be less than 1/3 of
the luminance in the im-
mediate surroundings. For
more remote parts of the
room, the difference in
luminance should be 1/5,
max. 1/10.
Glare limitation
Glare is one of the most
unpleasant visual prob-
lems of all. Being dazzled
by a general-diffuse lamp
or the reflection of a win-
dow on a computer screen
affects our visual acuity
and impedes our perform-
ance. Direct and reflected
glare can be largely
avoided by good room
and lighting design.
Modelling
Without light we cannot
see an object at all, with-
out shadow it is just a
two-dimensional image.
Only where light comes
from the right direction
and where the depth of
shadow is correct can we
perceive objects as 3D im-
ages and gauge distances.
To recognise three-dimen-
sional objects, surfaces
and structures, we need
light and shade.

More information is contained in booklet 1 of this series, “Lighting with
Artificial Light“.
Light and colour
The way we perceive colours
under artificial light depends on
the colour rendering properties
of the lamps. Lamps with good
colour rendering properties
produce natural colours
(Fig.
18)
, lamps with poor colour
rendering properties cause
colour distortion
(Fig. 19).
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14
16
18
20
5
Reflections on monitors
Where luminaires are
poorly shielded or wrongly
positioned, visibility is
impaired by disturbing re-
flections on monitors and
losses of contrast
(Fig. 33)
.
This is avoided by good
lighting design and good
luminaires
(Fig. 32)
.
Vertical illuminance
Schools and educational
establishments are com-
munication-intensive
places where clear iden-
tification of faces and in-
formation is essential. The
key lighting requirement
here is vertical illuminance,
i.e. uniform bright illumi-
nation of vertical surfaces
such as blackboards or
three-dimensional objects
such as people‘s faces.
For blackboard lighting,
wallwashers are a particu-
larly suitable choice be-
cause they illuminate the
writing surface uniformly
without casting shadows
or reflections
(Figs. 22
and 24)
. Where additional
board lighting is not pro-
vided, shadows are cast
onto the writing surface
(Figs. 23 and 25)
.
Direct lighting from above
often causes undesirable
shadowing on faces
(Fig.
27)
. In consultation zones,
this shadowing is reduced
by asymmetrical or direct/
indirect lighting
(Fig. 26).
Bright walls
Good wall and entrance
lighting helps people get
their bearings in a room,
makes for better contrasts
and emphasises room
zones. It also makes the
room look a livelier, more
interesting place
(Fig 28).
Direct/indirect lighting
Luminaires with direct and
indirect lighting compo-
nents permit free arrange-
ments of desks, reduce
the risk of reflected glare
and create a more agree-
able lighting atmosphere
(Fig. 30).
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17
19
21
22
23
24
25
26 27
28 29
30 31
32
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6
M
any educational
establishments
today consist of
large complexes of build-
ings with lots of special
classrooms, events and
sports halls, cafeterias and
refectories, administrative
offices and conference
zones. Schools, in par-
ticular, meet this descrip-
tion because a growing
number of them now
spread classes throughout
the day.
Every room in a school or
educational establishment
serves a particular pur-
pose, for which there are
special architectural solu-
tions with special lighting
requirements. Examples of
systems which meet those
requirements are found on
the following pages of this
booklet.
For any room in a new or
refurbished building, the
aim should be to find the
best way of harnessing
natural daylight and the
requisite artificial lighting.
Here, however, the impor-
tance of artificial lighting
is often underestimated,
although it plays a major
role in most classrooms.
In winter especially, the
available daylight is gen-
erally not adequate. For
media work with projec-
tors, windows need to
be darkened. And for
scientific experiments, a
special lighting situation is
frequently necessary.
However, planning artificial
lighting involves more than
just ensuring adequate
brightness in a room. A
differentiated lighting
design incorporating vari-
ous separately controlled
luminaire systems permits
the creation of lighting
scenes tailored to require-
ments. With dimmable
room lighting, separate
wallwashers at the front of
the room and additional
luminaires at the entrance
Light for learning
and perimeter, it is also
possible to stage multime-
dia presentations, lectures
and exhibitions with light-
ing fine-tuned for suitability
and safety.
Today, economical opera-
tion of lighting systems is
assured by energy-efficient
lamps and operating gear,
high-grade luminaires with
high light output ratios as
well as lighting control sys-
tems which automatically
adjust the brightness of
lamps to suit the daylight
component available and
deactivate lighting when
a room is not used. Mod-
ernising lighting systems
when premises are refur-
bished can reduce the
annual lighting costs of old
school buildings or other
educational establish-
ments by more than 60%.
But lighting design must
always focus primarily on
human beings, the ac-
tivities they perform in the
room in question and the
visual tasks they need
to address. What kind of
lighting is needed? How
much light is right? And
what kind of lighting sys-
tem is required to provide
it? Lessons conducted
from the front of the class
call for different lighting
than group work, presen-
tation area lighting has to
cater to different needs
than play area lighting,
and reading and writing
have different lighting
requirements than tasks
performed at computers or
machines.
On the following pages,
we look at the types of
room most commonly
encountered in schools
and educational establish-
ments and present model
solutions for them and
photographs showing
theory put into practice.
These are not a substitute,
however, for individual
lighting planning.
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7
FGL 3D Visualisation©
8
Classrooms with
fixed seating arrangements
I
n classrooms with fixed
seating arrangements,
the principal viewing
direction is towards the
blackboard. The desks
here are positioned per-
pendicular to the window
wall. Room lighting is
generally provided by lou-
vered luminaires arranged
parallel to the windows.
The deeper the classroom
is, the more rows of lumi-
naires are required. With
room depths up to eight
metres, three rows of
luminaires normally suf-
fice; in deeper rooms, four
or more rows should be
planned.
Depending on the ceiling
system, linear or square
louvered luminaires are
recommended. With
higher ceilings, pendant
luminaires with an indirect
lighting component are
also an option. These ad-
ditionally illuminate the
ceiling, giving the room a
more open, spacious ap-
pearance.
On an overcast day or in
winter, the incident day-
light from a window wall
is normally not enough to
provide adequate illumina-
tion for the desks in deeper
parts of the room. The
rows of luminaires should
therefore be separately
switched and dimma-
ble. The lighting can then
be adjusted for uniform
brightness throughout the
room.
Modern luminaires with
daylight sensors perform
this task and regulate
the distribution of light
automatically. Where very
little daylight is available,
all the luminaire rows are
activated and set at bright-
ness levels which rise with
room depth. As soon as
the daylight increases, the
luminaires are uniformly
dimmed down.
The blackboard needs
to be clearly visible from
every desk. Shadows and
reflections on the board
make it hard to read what
is on it and cause visual
fatigue. The result: loss
of concentration and
motivation. Wallwashers
with asymmetrical beams
provide the right lighting
at the front of the room,
delivering high vertical il-
luminance and avoiding
disturbing shadows and
reflections.
When positioning wall-
washers, care must be
taken to ensure adequate
planar illumination so
that the board can be
raised and any exten-
sions opened without any
part of the board being
outside the illuminated
area. Flipcharts or maps
positioned alongside the
board should also be
uniformly illuminated by
the wallwashers. For over-
head projector, beamer
or TV presentations, the
wallwashers should be
separately switched and
dimmable to enable the
illuminance to be adjusted
to suit the occasion.
Accent lighting can signifi-
cantly improve the visual
ambience of a classroom.
Supplementary wallwash-
ers or spots for illuminat-
ing notice boards highlight
displays in the room and
create a more differenti-
ated lighting landscape.
Additional downlights at
the room entrance pro-
vide more light for hazard
zones and can be linked to
the emergency lighting.
To help avoid unnecessary,
uneconomical lighting,
lighting systems can be fit-
ted with presence control
systems. When a room
is vacated, e.g. at break-
times or at the start of a
free period, the lighting is
automatically deactivated
and reactivated only when
the next person enters the
room. Such systems can
considerably reduce elec-
tricity bills for lighting.
35
36
9
Wallwashers provide uni-
form, shadow-free illumi-
nation for vertical surfaces
such as blackboards. They
also avoid reflected glare
and ensure good legibility
at every desk in the class-
room
(Fig. 36).
Daylight decreases with
room depth. Separately
switched and dimmable
rows of luminaires make
for uniform brightness
throughout the room. Lu-
minaires with daylight sen-
sors automatically control
or regulate light output
(Fig.
40).
40
Lighting tips
•
Separately switched rows of lumi-
naires can be activated or deactiva-
ted according to the amount of
daylight available.
•
Wallwashers for blackboard lighting
heighten visual comfort.
•
Presence control systems save
energy by automatically deactiva-
ting lighting when a room is vacated.
37
38
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FGL 3D Visualisation©
10
Classrooms with
variable seating arrangements
C
lassrooms are
often used by
dif-
ferent classes.
In
many cases, they are oc-
cupied by school groups
in the mornings, by project
groups in the afternoon
and used for parents‘ eve-
nings or adult education
courses in the evening. As
a result, desks and chairs
are repeatedly rearranged
to meet the different re-
quirements. U-shaped
arrangements of desks
give way to desks pushed
together for group work,
which then give way in
turn, perhaps, to a classi-
cal arrangement of rows.
There is no principal view-
ing direction in the room
and no defined presenta-
tion zone.
Daylight and artificial light-
ing need to be harnessed
to cater for this flexible
room use. Particularly im-
portant here is daylight
control. Where desks are
assembled in U-shaped
arrangements or put
together to form group
desks, many of the group
face the window. On a sun-
ny day, the luminance - the
impression of brightness
- for anyone looking out of
the window may be tens
of thousands of candelas,
whereas the luminance for
eyes turned into the room
is considerably lower.
Constant changes of con-
trast place a great strain
on our eyes and lead to
fatigue and loss of con-
centration. So for balanced
brightness distribution, lou-
ver blinds or vertical blinds
are needed to control day-
light incidence according
to the position of the sun.
Modern lighting control
systems with daylight sen-
sors automatically adjust
the angle of the blinds and
adapt the artificial lighting
component accordingly.
Classes no longer need to
be interrupted while some-
one closes or opens blinds
or regulates the room light-
ing.
Just as with fixed seating
arrangements, artificial
lighting for variable con-
stellations of desks needs
to be designed to mini-
mise glare. Lamps should
not be directly visible from
anywhere in the room. Lu-
minaires with direct/indirect
lighting components and
appropriate shielding are
particularly suitable here.
They permit free arrange-
ments of furnishings and
largely avoid direct glare
and reflected glare on
glossy materials.
For communication-inten-
sive teamwork or the dis-
cussion that takes place on
parents‘ evenings, direct/
indirect luminaires have
the additional advantage
of providing very uniform
illumination throughout the
room. Modelling is more
balanced and the lighting
is softer and more agree-
able. Faces, in particular,
are cast in a more natural
and more attractive light.
Lamps of warm light colour
add to the visual ambience
required for the room.
Even in classrooms with
variable seating arrange-
ments, the normal presen-
tation area in front of the
blackboard still requires
special attention. Sepa-
rately switched and dim-
mable wallwashers provide
correct, i.e. reflection-free
high-angled lighting for the
board. For flexible presen-
tation lighting of the kind
required for presenting
group projects, room light-
ing should be provided
by separately switched
and dimmable groups of
luminaires. Media presen-
tations with projectors can
thus be seen clearly in all
parts of the room.
With lighting control systems, lighting and louver
blinds can be tailored to room use - for media presen-
tations as well.
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42
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43
44
45
Lighting tips
•
Where desk arrangements are variable,
care must be taken to ensure glare-free
vision in the direction of the windows
and in the room.
• Light-control blinds should be provided
so that windows can be darkened.
• The lighting should be designed to
cater separately for different presen-
tation areas.
FGL 3D Visualisation©
12
Kindergarten classrooms
A
t no time in our
lives do we have
the capacity for
learning that we have in
early childhood. In many
cases, early promotion of
learning plays a crucial
role in shaping our willing-
ness to learn in later years.
Where kindergartens and
day care centres arouse
children‘s curiosity and
convey to them the thrill
of acquiring skills and
making discoveries for
themselves, they lay the
foundations for successful
life-long learning.
Among the fundamental
things children learn at kin-
dergartens and day care
centres are spatial percep-
tion and recognition of col-
ours, objects and people.
The right lighting plays a
crucial role here.
To develop 3D vision, we
need light and shade. In
a uniformly bright room
in which objects cast no
shadows and there are no
surfaces lighter or darker
than others, we are able
to gauge neither size nor
distance.
Harmonious brightness
distribution in a room
makes for subtle grading
in lighter and darker parts
of the room and differ-
entiated modelling of all
objects. In a room where
brightness is harmoniously
distributed, we can move
around securely and con-
fidently because we have
no problem seeing and
registering our surround-
ings in 3D.
Recognising colours and
surfaces, textures and
materials is one of the
most important visual
challenges of everyday
life. Once we have devel-
oped the requisite skill, we
can generally tell instantly
whether an object is hard
or soft, heavy or light.
Identification of colours
and surfaces is particularly
important here.
Colours are created by
light bouncing off sur-
faces. What we perceive
as the colour of an object
is actually the light of a
certain wavelength which
is not absorbed by the
object‘s surface. So, for
seeing and identifying col-
ours and objects correctly,
good lighting and good
colour rendering by lamps
are crucial.
In kindergartens and day
care centres, the empha-
sis is on activities which
are both educational and
fun. Running around, form-
ing groups and handling
small objects are activi-
ties for which good room
lighting is important. Often,
however, groups engage
in different activities at
the same time. While one
is actively honing skills,
another might be taking a
short break. Differentiated
lighting for different play
and rest zones - made
possible by zonal dimming
control - facilitates this.
Children need to be able
to play - even on cold and
rainy days when the play-
ground is covered in snow
or under water. For play-
ing indoors, the lighting
needs to be adequately
bright. Where rooms are
not bright enough, the risk
of accidents increases and
the children‘s motivation
declines. The higher the
level of lighting for play, the
more likely children are to
become actively involved,
feel a sense of wellbeing
and be willing to learn.
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