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Abstract

Measuring the increase in productivity due to the influence of lighting is not a simple task. In a production plant, information about productivity is an important indicator of performance. This paper describes an interdisciplinary approach of experts from the fields of psychology, ergonomics, medicine and lighting technology jointly applying a set of measuring instruments to describe and analyze the effects on well-being and stress, motivation and sleeping quality, the capacity to regenerate after work, as well as the quality of the lighting situation could be useful.
8
LIGHTING QUALITY AND ITS EFFECTS ON PRODUCTIVITY AND
HUMAN HEALTS
Ružena Králiková
1
- Miriama Piňosová
2
- Beata Hricová
3
Abstract: Measuring the increase in productivity due to the influence of lighting is not a simple task. In a production plant,
information about productivity is an important indicator of performance. This paper describes an interdisciplinary
approach of experts from the fields of psychology, ergonomics, medicine and lighting technology jointly applying a set of
measuring instruments to describe and analyze the effects on well-being and stress, motivation and sleeping quality, the
capacity to regenerate after work, as well as the quality of the lighting situation could be useful.
Keywords:
Lighting quality, illuminance, colour spectrum, energy saving, LED
1 INTRODUCTION
Lighting can do so much more than illuminate.
It can enhance form and function, improve safety and
security and create flexible spaces that adapt to the task
at hand. Energy-efficient lighting solutions for industry
can reduce environmental impact and save on costs, at
the same as increasing quality and productivity. At
present of soaring energy prices and legislation targets
it can also help companies to achieve the sustainability
goals. Good lighting in the workplace with well-lit
task areas is essential for optimizing visual
performance, visual comfort and ambience, especially
with an ageing workforce. And the beneficial effects of
good lighting extend much further than it was
originally thought. In fact, over the last two decades
medical science has consistently shown that light has a
positive influence on health and wellbeing. With better
lighting using of ecological lighting sources (e.g.
LED), performance can be improved by speeding up
tasks and reducing failure rates and when added to the
energy saving aspects. Sustainable lighting can be a
powerful tool to improve business also [9].
Taking into account both - natural and artificial
light, its intensity and distribution so that visual
comfort is secured as visual comfort is undoubtedly
one of the key productivity drivers and, at the same
time, eyesight problems are widely associated with
poor working conditions - special consideration has to
be given to the subject.In a production plant,
information about productivity is an important
indicator of performance.
Measuring the increase in productivity due to
the influence of lighting is not a simple task. Where an
increase is observed, this may often be due to a variety
of influences. In the sphere of lighting, there are many
possibilities to create good visual conditions, even
though static lighting meeting standard requirements as
a minimum. For dynamic brightness sequences, it is
possible to modify the brightness or color temperature
of the lighting. The effect on the workers may be
assessed through various interviews, questionnaire
surveys and measurements.
2 LIGHT QUALITY FACTORS
A number of different approaches have been
suggested to define lighting quality. The definition that
seems most generally applicable is that lighting quality
is given by the extent to which the installation meets
the objectives and constraints set by the client and the
designer. In this way lighting quality is related to
objectives like enhancing performance of relevant
tasks, creating specific impressions, generating desired
pattern of behaviour and ensuring visual comfort [2, 3].
Lighting quality is depends on several factors. It
depends largely on people’s expectations and past
experiences of electric lighting. Those who experience
elementary electric lighting for the first time, for
example, in remote villages in developing countries,
have different expectations and attitudes towards
lighting from the workers in industrialized countries.
There are also large individual differences in what is
considered comfortable lighting, as well as cultural
differences between different regions. Lighting quality
is much more than just providing an appropriate
quantity of light. Other factors that are potential
contributors to lighting quality include e.g. illuminance
uniformity, luminance distributions, light color
characteristics and glare. There are many physical and
physiological factors that can influence the perception
of lighting quality. Lighting quality cannot be
expressed simply in terms of photometric measures nor
can there be a single universally applicable recipe for
good quality lighting [2]. Light quality can be judged
according to the level of visual comfort and
performance required for our activities. This is the
visual aspect. It can also be assessed on the basis of the
pleasantness of the visual environment and its
adaptation to the type of room and activity. This is the
psychological aspect. There are also long term effects
of light on our health, which are related either to the
INTERNATIONAL JOURNAL OF INTERDISCIPLINARITY IN THEORY AND PRACTICE
ITPB - NR.: 10, YEAR: 2016 – (ISSN 2344 - 2409)
9
strain on our eyes caused by poor lighting (again, this
is a visual aspect), or to non-visual aspects related to
the effects of light on the human circadian system [12].
The illumination have be designed by the available
financial budgets and resources, time terms for
completing the project and according to suitable
practices and design approaches that need to be
followed. Lighting quality means achieving an optimal
balance among human needs, architectural
considerations, and energy efficiency, Figure 1 [13].
Arc hitectur e
and other
Buil ding or
Site -related Issues
Form
Comp ositon
Style
Codes and stan dards
Safety and secu rity
Daylig hting
Hum an Nee ds
Visibil ity
Task p erforma nce
Visual comfor t
Social commu niction
Mood and atm osphere
Health , safety , well be ing
Aesthe ric judg ment
Eco nomics,
Ene rgy Effi ciency
and the Env ironme nt
Install ation
Maint enance
Opera tion
Energ y
Enviro nment
Fig. 1 Lighting quality
3 VISUAL ASPECTS OF THE LIGHTING
The influence of artificial lighting on the
psychophysiological well-being and the productivity of
workers in a production plant depends on kind of
lighting source that with respect to:
Brightness – illuminance.
Light colour – spectrum.
Light distribution luminance distribution in
the room.
The effects of artificial lighting on people are
more pronounced, that natural influence of daylight
inside working hours is very low especially during
winter season. One of the major aspects of the lighting
practice and recommendations is to provide adequate
lighting for people to carry out their visual tasks.
Ensuring adequate and appropriate light levels -
quantity of light is only an elementary step in creating
comfortable and good-quality luminous and visual
environments. Lighting that is adequate for visual tasks
and does not cause visual discomfort is not necessarily
good-quality lighting. Depending on the specific
application and case, either insufficient lighting or too
much light can lead to bad-quality lighting. There are a
number of lighting-related factors that may cause
visual discomfort. The current indoor lighting
recommendations give ranges of illuminance values for
different types of rooms and activities [3].
In addition, guidelines on light distribution in a
space, the limitation of glare, and the light color
characteristics are given. The color characteristics of
light in space are determined by the spectral power
distribution (SPD) of the light source and the
reflectance properties of the surfaces in the room. The
color of light sources is usually described by two
properties:
Namely the correlated color temperature
(CCT).
General color rendering index (CRI).
The color appearance of a light source is
evaluated by its correlated color temperature (CCT).
For example, incandescent lamps with CCT of 2700 K
have a yellowish color appearance and their light is
described as warm. Certain type of fluorescent lamps
or white LEDs have CCT of around 6000 K with bluish
appearance and light described as cool.
The CRI of the CIE measures how well a given
light source renders a set of test colors relative to a
reference source of the same correlated color
temperature as the light source in question of
International Commission on Illumination (CIE). The
general CRI is calculated as the average of special
CRIs for eight test colors. The reference light source is
Planckian radiator (incandescent type source) for light
sources with CCT below 5000 K and a form of a
daylight source for light sources with CCT above 5000
K. The higher the general CRI, the better is the color
rendering if a light source, the maximum value being
100. The Light source spectrum, i.e. radiant power
distribution over the visible wavelengths, determines
the light color characteristics. Examples of spectra of
the lamps are shown on Fig. 2 - 5 [12].
Fig. 2 Light source spectrum – example of spectra of
an incandescent lamp (CCT = 2690 K, CRI = 99) [14]
Fig. 3 Light source spectrum – example of spectra of a
compact fluorescent lamp (CCT = 2780 K, CRI = 83)
[14]
10
Fig. 4 Light source spectrum - example of spectra of a
white LED lamp (CCT = 6010 K, CRI = 78) [14]
Fig.5 Emission spectra from daylight and typical
incandescent, fluorescent, and LED builds [14]
4 LIGHTING STANDARDS
A completely uniform space is usually
undesirable whereas too nonuniform lighting may
cause distraction and discomfort. Lighting standards
and codes usually provide recommended illuminance
ratios between the task area and its surroundings
according ETN EN 12 464-1. Most indoor lighting
design is based on providing levels of illuminances
while the visual system deals with light reflected from
surfaces i.e. luminances. For lighting there are
recommended luminance ratios between the task and
its immediate surroundings [7].
Room surface reflectances are an important part
of a lighting system and affect both the uniformity and
energy usage of lighting. Compared to a conventional
uniform lighting installation with fluorescent lamps,
LEDs provide opportunities to concentrate light more
on actual working areas and to have light where it is
actually needed. This provides opportunities to increase
the energy efficiency of lighting in the practise.
5 PSYCHOLOGICAL ASPECTS
The luminous environment can be perceived in
many ways e.g. as more or less agreeable, more or less
attractive, and more or less appropriate to the function
of the space, more or less highlighting the company
image. Variations of luminances and colors can
strengthen attractiveness, trigger emotions, and affect
workers mood, the impact of lighting depends much on
the individuals and their state of mind. Unacceptable
lighting conditions may impact on task performance
and thus productivity through motivation. A lighting
installation that does not meet the user’s expectations
can be considered unacceptable even if it provides the
conditions for adequate visual performance. People
perceive their luminous environment through their
eyes. [10]
6 BIOLOGICAL FACTORS
Light has also effects that are fully or partly
separated from the visual system. Biological effects of
light are called also the non-visual effects of light,
related to the human circadian photoreception. The
biological effects of light and their effects on human
performance are not yet very well known. Research
work is needed to generate an improved understanding
of the interaction of the effects of different aspects of
lighting on behavioral visual tasks and cortical
responses and on how the biological effects of lighting
could be related to these responses. The biological
effects of light and their effects on human performance
are not yet very well known. Lighting should be
designed to provide people with the right visual
conditions that help them to perform visual tasks
efficiently, safely and comfortably. The luminous
environment acts through a chain of mechanisms on
human physiological and psychological factors, which
further influence human performance and productivity,
Figure 6 [4].
7 THE PROCUCTIVITY AND LIGHTING
Lighting should be designed to provide people
with the right visual conditions that help them to
perform visual tasks efficiently, safely and
comfortably. The luminous environment acts through a
chain of mechanisms on human physiological and
psychological factors, which further influence human
performance and productivity [4].
The effect of lighting on productivity is
ambiguous. The difficulty in finding the relations
between lighting and productivity is that there are
several other factors that simultaneously affect human
performance. These factors include motivation,
relationships between workers and the management
and the degree of having personal control to the
working conditions [2]. With appropriate lighting the
ability to perform visual tasks can be improved and
visual discomfort can be avoided. This can provide
conditions for better visual and task performance and,
ultimately, productivity.
The difficulty of field studies in working
environments is the degree of experimental control
required. Several studies have investigated the effect of
increase in illuminance on task performance. However,
illuminance is only one of the many aspects in the
lighting conditions. In making changes to lighting,
11
which lighting aspects are changed (e.g. illuminance,
spectrum, and luminance distribution) and whether
there are other factors that are simultaneously changed
in the working conditions (e.g. working arrangements,
people, supervision of work) need to be controlled and
analyzed. Recently, several studies are investigating
the effects of light spectrum on human performance
and the possibilities to use blue-enriched light to
improve human performance through the non-visual
effects of light. Poor lighting conditions can easily
result in losses in productivity of employees and the
resulting production costs of the employer can be much
higher than the annual ownership cost of lighting.
Luminous Environment
Illuminance
&
Illuminance
Uniformity
Illuminance
&
Illuminance
Distribution
Glare Spectral
Power
Distribution Daylight Lighting
System
Characteristics
Lighting
Control
Flicker Disability
Glare Discomfort
Glare Veiling
Reflections Spectrum
Correlated
Colour
Temperature
Colour
Rendering
Index
Amount
of
Light
Human Performance & Productivity
Seasonal
Affective
Disorders
Eyestrain
Aesthetic
Judgment
Mood
Effects
Arousal
Visual &
Task
Performance
Visibility
Circadian
Rhythms
Visual
Comfort
Social
Interacion &
Communication
Visual
Acuity
Acceptability
&
Satisfaction
H
u
m
a
n
F
a
c
t
o
r
s
Direct /
Indirect
Lighting
Light
Sources
Spectrum Amount
of
Light
AgeingPreferences
Fig.6 Luminous environment and human performance [4]
8 DISCUSSION
The effects of lighting conditions on
productivity have been published in the several studies.
The earliest studies indicated that lighting conditions
can improve performance by providing adequate
illuminance for the visual tasks. Their results are
sometimes contradictory. For example, a study in
working environment indicated that an increase in
illuminance from 500 lx to 1500 lx could increase the
performance of workers by 9%, while another study
showed that lower illuminance levels (150 lx) tended to
improve performance of a complex work
categorization task as compared to a higher level (1500
lx). A field study in industrial environment measured
direct productivity increases in the range from 0 to 9 %
due to changes in lighting.
The literature shows some examples of null
results than clear-cut effects of illuminance on task
performance, over a wide range of illuminance levels
and for a variety of complex and simple tasks in
working environment [5].
9 CONCLUSIONS
Observing the effect of light on human beings
and health is a topic that is addressed by various
sciences such as psychology, medicine, ergonomics
and lighting technology. The interdisciplinary
application of methods shows that measuring the effect
of lighting on human beings is complex. If no results
are obtained, that does not mean that there is no effect,
but that the instruments of observation and
measurement have not been optimally used. Further
12
efforts are required to improve the measuring methods,
instruments and evaluations.
Acknowledgement: This paper was written in frame of
the work on the projects VEGA 1/0537/15 “Research
of influence of chosen parameters of working
environment on working power and productivity”. This
work was supported by the Slovak Research and
Development Agency under the contract No. APVV-
0432-12.
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[3] Gligor, A.; Grif, H.; Oltean, S.: Considerations on
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[4] Gligor, V.: Luminous Environment and
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[5] Hughes, P.C., Mcnelis, J.F.: Lighting,
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[7] STN EN 12464-1, Light and lighting – Lighting at
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[14] https://www.comsol.com/blogs/calculating-the-
emission-spectra-from-common-light-sources/
AUTHORS ADDRESSES
1
doc. Ing. Ružena Králiková, PhD.
Faculty of Mechanical Engineering, Department of
Processing and Environmental Engineering, Technical
University of Kosice, Slovak Republic
E-mail: ruzena.kralikova@tuke.sk
2
Ing. Miriama Piňosová, PhD.
Faculty of Mechanical Engineering, Department of
Processing and Environmental Engineering, Technical
University of Kosice, Slovak Republic
E-mail: m.p.tuke@gmail.com
3
Ing. Beata Hricová, PhD.
Faculty of Mechanical Engineering, Department of
Processing and Environmental Engineering, Technical
University of Kosice, Slovak Republic
E-mail: beata.hricova@tuke.sk
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Lighting conditions in industrial operations are currently at a level, which in many cases does not satisfy the requirements set out by legislation and standards. Slovakia has highly energy-intensive industrial structure, where dominates the engineering industry. The proportion of electricity attributable to lighting is significant and not negligible. Installation and operation of energy efficient lighting systems is in most cases not yet considered a major priority, because the available funds are primarily used for the operation, modernization of production process, and other related activities, that are directly related to the production, and the existence of industrial enterprises and institutions. This paper presents new trends and progressive strategies to reduce energy consumption of lighting systems. In new installations energy efficient lighting costs are little more to provide than the older less efficient kind, but consumption of energy are lower, economical and environmental friendly.
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