1. PHOTOMETRIC ANALYSIS OF
NEW LIGHTING SYSTEMS
TU Ilmenau (Ilmenau University of Technology) Study, subject
area: lighting technology
Zumtobel Lighting & Siteco
Excerpt
Zumtobel Lighting Junghans; Sejkora; Petschulat
Siteco Hr. Sabla
21.06.2006
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2. TU Ilmenau Study
BASIC SUBSTANCE OF STUDY
Contrast is an appropriate criterion for describing the
quality criteria for new requirements in modern offices:
Differences in brightness and brightness levels
influence adaptation and hence contrast sensitivity
People use contrast to recognise visual details
Contrast describes the underlying conditions in the
office
1. Differences in brightness in the room
Brightness distribution in proportion and on walls,
ceiling, floor
Room brightness distribution in relation to visual task
2. Contrast rendition in order to identify visual task
Contrast perception on screens
Contrast perception at visual task (irritation caused
by reflected glare, e.g. on paper, as a function of
luminance of light source and its arrangement)
Modern lighting technologies such as waveguides,
microprism systems and Mellow Light/secondary
systems address these issues comprehensively
2 ILMENAU STUDIE · 9. März 2006 EXTRAKT ZUR ILMENAU STUDIE · 21.06.2006 © ZUMTOBEL LIGHTING GMBH

3. TU Ilmenau Study
CONTRAST RATIOS – WHAT IS CONTRAST?
Contrast perception
People perceive contrasts, i.e.
differences in brightness or contrast
improve visual performance and visual
comfort
Specifically: higher or lower contrast
Ergonomic lighting for spatial
perception/a sense of well-being and
trouble-free activity must provide the Example of inadequate optotype contrast and poor CRF value
following contrast ratios
- Room - low contrast, i.e. balanced
differences in brightness on surfaces
that enclose room
- Workplace - high optotype contrast
without distracting reflections that
reduce contrast, i.e. high CRF value
- Monitors – high optotype contrast
without distracting reflections that
reduce contrast, regardless of
inclination and alignment relative to
luminaire Example of good optotype contrast and good CRF value
3 ILMENAU STUDIE · 9. März 2006 EXTRAKT ZUR ILMENAU STUDIE · 21.06.2006 © ZUMTOBEL LIGHTING GMBH

4. TU Ilmenau Study
ROOM CONTRAST RATIO
15
cd/m²
17 %
Room
Brightness distribution in room has a
17
decisive influence on users’ level of cd/m²
adaptation and subjective sense of 20 %
well-being 23
cd/m²
27 %
15
cd/m²
The more balanced the contrast ratios
17 %
of the lighting installation in a room,
the greater the preference expressed 34
by user groups cd/m²
39 %
Care must be taken to ensure gentle 36
cd/m²
transitions in brightness 41 %
51
cd/m²
59 %
17
cd/m²
20 %
4 ILMENAU STUDIE · 9. März 2006 EXTRAKT ZUR ILMENAU STUDIE · 21.06.2006 © ZUMTOBEL LIGHTING GMBH

5. TU Ilmenau Study
RATING ACCORDING TO USERS’ SUBJECTIVE SENSE OF
WELLBEING
• Waveguide systems
1.) Balanced ID ratio, bright ceiling and
bright walls, optic appears bright and is
low-glare
• Microprism systems, indirect/direct
Balanced ID ratio, bright ceiling and
bright walls, optic appears bright and is
low-glare
2.)
• Secondary systems
Extremely wide-angle light distribution
with plenty of brightness on the wall and
ceiling brightening
• Microprism systems, direct
Bright appearance, no brightening of
3.) ceiling
• Louvre systems
Brightness is provided exclusively in the
task area, there is hardly any direct
illumination of room peripheries
5 ILMENAU STUDIE · 9. März 2006 EXTRAKT ZUR ILMENAU STUDIE · 21.06.2006 © ZUMTOBEL LIGHTING GMBH

6. TU Ilmenau Study
TASK AREA CONTRAST RATIO
• Task area
High contrast rendition, i.e. high
CRF value, is indispensable for
ensuring trouble-free optotype
recognition
Arranging luminaires with direct
light distribution above the visual
task and the associated reflections
adversely affect this criterion
Modern lighting systems with a
well-graded direct/indirect ratio and
diffusers that direct light in order to
reduce direct luminance are one
possible solution
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7. TU Ilmenau Study
RATING ACCORDING TO CONTRAST IN TASK AREA
Waveguide systems
1.) • Laterally injected light
• Large indirect component and balanced brightness
between optic of luminaire and ceiling
2.) Microprism systems, indirect/direct
• Fully shielded light source
• Balanced indirect/direct ratio
Secondary systems
3.) • Completely covered light source
• Balanced differences in brightness between surface
of luminaire and ceiling area in immediate vicinity of
luminaire
4.) Microprism systems, direct
• Completely covered light source, otherwise direct
light only
5.) Louvre systems
• Depending on arrangement, exposed light source
results in greater contrast reduction in task area
7 ILMENAU STUDIE · 9. März 2006 EXTRAKT ZUR ILMENAU STUDIE · 21.06.2006 © ZUMTOBEL LIGHTING GMBH

8. TU Ilmenau Study
SCREEN CONTRAST RATIO
Angular viewing
Screen
Contrast rendition on screens is an
additional criterion that provides a
conventional description of glare control
in accordance with existing published
standards
Various screen technologies, inclination
angles and layouts make geometrical
glare control more difficult/make Inclination and type of screen
adequate contrast rendition on the as determining factors
screen necessary
Modern screens offer improved display
quality and are therefore less sensitive to
reflections
Modern screens achieve optimum
contrast rendition even in case of
critical layouts and inclination angles Various contrast rendition situations in case of
inclined screen and different lighting situations
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9. TU Ilmenau Study
RATING ACCORDING TO CONTRAST ON SCREEN
Waveguide systems
Completely covered light source, luminaire provides glare
1.) control for light radiated at shallow and steep angles.
Surroundings reflected on monitor have low brightness
contrast
Large indirect component
2.) Microprism systems, indirect/direct
• Fully shielded light source, luminaire provides glare control
for light radiated at shallow and steep angles.
Surroundings reflected on monitor have low brightness
contrast
50%/50% indirect/direct ratio
3.)
Secondary systems
Fully shielded light source, luminaire provides glare control
for light radiated at shallow and steep angles.
Light exit surface has balanced brightness
4.)
Microprism systems, indirect/direct
Fully shielded light source, luminaire provides glare control
for light radiated at shallow and steep angles.
Light exit surface has balanced brightness
Louvre systems
Exposed visible light source excels in critical layouts
Good glare control for steeply inclined screens where
screens are arranged between luminaires
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10. TU Ilmenau Study
ALL CRITERIA TAKEN INTO CONSIDERATION TOGETHER
4 individual criteria 4 Arrangements 3 Screen types / 5 Lighting
Contrast on screen inclination angles Systems
CRF at workplace •CRT upright •Light Fields ID
UGR value •TFT upright •AERO
•TFT inclined •Mellow Light IV
Em at monitor level •Light Fields Direct
•Louvre
gut highly suitable
geeignet
mit suitable with restrictions
Einschränkung geeignet
bedingt geeignet
suitable to limited extent
10 ILMENAU STUDIE · 9. März 2006 EXTRAKT ZUR ILMENAU STUDIE · 21.06.2006 © ZUMTOBEL LIGHTING GMBH

11. TU Ilmenau Study
Recommended luminaire applications depending on lighting
situation (taking all criteria into account)
VERGLEICH MODERNER LICHTSYSTEME
STUDIE ILMENAU GEWICHTUNG 4
Light Fields ID AERO Mildes Licht IV Light Fields Direkt Raster
CRT 1,7 1,8 1,6 1,4 1,2
Blickrichtung quer zu den Leuchten TFT steil 2,1 2,4 2,0 2,0 1,5
Beleuchtungssituationen
TFT flach 1,8 2,2 1,7 1,7 1,1
CRT 1,7 1,9 1,3 1,5 1,4
Blickrichtung paralell zu den Leuchten TFT steil 2,1 2,4 2,0 2,0 1,8
TFT flach 1,9 2,1 1,9 1,6 1,5
CRT 1,8 1,9 1,5 1,7 1,2
Blickrichtung diagonal zu den Leuchten TFT steil 2,2 2,4 2,0 2,1 1,5
TFT flach 1,9 2,2 2,0 1,7 1,2
CRT 1,5 1,7 1,5 1,3 1,0
AP Ausrichtung unter den Leuchten TFT steil 2,0 2,3 1,9 1,9 1,4
TFT flach 1,6 2,1 1,5 1,4 0,8
Mittelwert 1,9 2,1 1,7 1,7 1,3
gut geeignet gemäss Kriterien UGR, CRF und Reflexe, Bel.Stärke Monitor
mit Einschränkung geeignet gemäss Kriterien UGR, CRF und Reflexe
bedingt geeignet gemäss Kriterien UGR, CRF und Reflexe
Summing up, for offices where a completely user-selectable layout is a
requirement, results are as follows for a) Reflections, b) UGR, c) CRF and d)
EMmonitor:
- Waveguides are highly suitable for all layouts and all types of screens
- Microprism systems ID and secondary systems for all layouts and TFT screens
- Microprism systems (direct) for all layouts and steeply inclined TFT screens
- Louvres are only suitable for parallel layouts and steeply inclined screens
11 ILMENAU STUDIE · 9. März 2006 EXTRAKT ZUR ILMENAU STUDIE · 21.06.2006 © ZUMTOBEL LIGHTING GMBH