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Prof. Dr. Meltem YILMAZ
While light is a creative medium, its most basic
function is to enable us to see. Our visual acuity relies
on the quantity of light and its spectral distribution.
Seeing is therefore not only about distinguishing light
and shade, but also color.
The movement of light is a linear process where time
and space meet. Any moment reveals frozen
movement in time. We have evolved to respond to
daily and seasonal change brought about by the
movement of the sun, the moon and the stars.
Through the passage of light we track the change of
day into night as well as form and surfaces moving in
In the 20th century, the electric light has radically changed our way
of life. The rhythm of life was for the centuries determined by the
cyclical succession of day and night. It was only the emergence of
electric lighting that enabled man to break away from this
imperative rhythm. All at once, technology gave man the
possibility of warding off darkness and imagining a different world.
Our modern society is equally dependent on abundantly available
artificial light in any place and at any time. It is not only necessary
to guarantee the continuity of our activities, but also to give shape
and atmosphere to our visual perception of the environment,
independent of the availability of daylight .
For all architectural spaces whose envelopes are penetrated
by any opening to the exterior environment, lighting design
begins with recognition of the entry of daylight. It is a first
consideration because the presence of daylight in an interior
strongly influences spatial perception and also changes the
color of surfacing materials in terms of how they appear
elsewhere in the room under a number of different kinds of
electric illumination.
The amount of sunlight reflected about an interior is
determined by the size and shape of apertures in the spatial
envelope – as they relate to the proportions of a room.
Direct daylight will penetrate deeper into a room the higher
the top of the window is above the floor.
Windows can reduce
dependence on electric
lighting and lower energy
costs. Passive solar design
calls for south-facing
windows, but it is important
not to neglect daylighting in
other parts of the building.
When planning for good
daylighting, we have to consider
the illumination provided by the
sky rather than direct sunlight,
which is often undesirable
Good daylighting is not simply a function of
the quantity of light. In fact, some techniques
that increase the quantity of daylight can
actually decrease its quality.
The two main quality issues are glare and
light distribution. Glare can be either disabling
or discomforting. It is disabling when it
interferes with the ability to see. It is
discomforting when there is excessive
contrast between light and dark surfaces in a
room. Glare does not nesessarily increase
with increasing window size.
Room Finishes: For
maximum daylight
levels,uniformity and the
least glare, room
surfaces should have
matte finishes. Shiny
finishes create
reflections that result in
Glass Type: Glazing that allows the highest
transmission of the visible portion of the solar
spectrum provies the highest daylight levels.
Window Position: The higher the window, the
greater the Daylight Factor and the deeper the
penetration of daylight into the space.
Extending the window to the floor does little to
increase daylight levels. Clerestory windows
that allow deep penetration of daylight while
avoiding normal viewing angles are a good
daylighting strategy.
While up to the mid-20th century almost all schools and workplaces
used daylight as their primary source of lighting, the advent of
inexpensive energy and the proliferation of fluorescent lights in the
1950s and 1960s made daylight as an illumination source almost
When energy costs began soaring in the 1970s the ‘glazed skin’
look of many buildings became an expensive, though popular and
attractive, liability that often increased the costs of both heating and
cooling. Cooling, in particular, was a major cost, leading to the
elimination of solar gain-the heat generated by direct natural
sunlight through windows.
New construction deemphasized direct sunlight and brought forth
lower ceilings and lower building skin-to-volume ratios. Dropped
ceilings, heavily tinted glass, and insulating panels, designed to
reduce heat from windows, gained widespread acceptance.
The net result of this change in architectural and design priorities
(and realities) for public buildings of all types has been a dramatic
reduction in the amount of daylight available to students in schools
and working people at their jobs.
Recently, this trend is being reversed for two reasons. First is the
cost. Along with heating and cooling expenses, the use of electricity
to provide workplace/school lighting adds considerable overhead to
the overall cost of operating a building. Not only is daylighting
cheaper ( a net energy benefit), it is intrinsically more efficient than
any electric source because it provides greater amounts of
brightness per unit of heat content (lumen per watt).
Second, a growing interest in the influence of the indoor environment
on health, productivity and higher retail sales has resulted in growing
interest in the potential benefits that day lighting can bring toward
reaching these goals.
sustainable architectural concept,
illumination of spaces with day
lightning has become more
important than ever.
The main principles of sustainable
architecture are;
 Energy : the usage of renewable
consumption of artifical light.
 Land
Use: It is not a
‘commodity’, it is tha base of life.
 Local Material: Renewable local
materials have to be used.
Daylight is generally perceived as more attractive and
comfortable than artificial light. There are several
reasons for this:
Light emitted by the sun
covers a wide spectrum of
colors. The blend of these
colors makes up white
daylight. Artificial light
sources cannot exactly
reproduce the color spectrum
of the sun. The eye senses
this and reacts by tiring more
Daylight is dynamic. It varies
through the seasons and
times of the day, the position
of the sun and cloud cover.
Artificial light is static.
The required amount of artificial light in interior space is set at a level
required for minimum comfort. Daylight in interior spaces often
reaches considerably greater light levels, which is perceived to be
more pleasant.
Daylight is emitted by all sides of the celestial hemisphere and by the
sun. Its distribution results in the illumination of the environment.
This kind of illumination is comfortable for the eye.
A further advantage of daylight is its potential for energy saving. All
additional daylight not only means an increase in visual comfort, but
also an energy saving in artificial lighting. Until recently, this has
hardly been recognized. Contemporary energy-efficient architecture
no longer means merely improving insulation, but intelligent daylight
The drive to save energy has set off a search for ways to maximize
the effective use of daylight while at the same time reducing the
associated thermal radiation. The recent association of the two
disciplines of daylight planning and indoor climate technology has
yet to be put into architectural practice. In addition to the ecological
and economic advantages of a good supply of daylight in a building,
planned use of natural light enhances design and has appositive
effect on the physical and psychological well-being of its users.
Standart Glazing
The basic method of
maximizing daylight intake
to the interiors is glazing.
-Daylight transmittion in standart glazing.
In Conventional glazing;
Some conflictions can
be occurred due to the
heat and day lightning
These problems can be
solved with advanced
glazing systems.
Advanced glazing systems have special features, such as
selective coatings or low emmisitivity window glazings. They
can be specified which are transparent to daylight and are
opaque to potentially detrimental UV radiations.
One of the sample of advanced glazing systems
Advanced glazing systems;
 Cut energy consumption,
 Prevent associated pollution sources,
 Reduce peak demand,
 Enhance daylighting performance,
 Improve occupant comfort.
One of the sample of vacuum based glazing system
Other benefits include less air leakage and warmer glazing surface
temperatures, which improve comfort and minimize condensation. These
high-performance windows feature multiple lights of glass, specialized
transparent coatings, insulating gases sandwiched between panes of glass,
and improved frames.
Issues to consider include:
Shading and sun control
Visual requirements (glare, view, privacy)
Heat gains and losses
Thermal comfort
Condensation control
Ultraviolet control
Acoustic control
Security issues
Color effects
Energy requirements
Daylight performance
Although the source of daylight is the sun, surfaces and
objects within a space reflect and scatter daylight. An
increase in visibility and comfort can be achieved through
increasing room brightness by spreading and evening out
brightness patterns.
A reduction in intensity occurs from reflecting and partially
absorbing light throughout a space. A light shelf, if properly
designed, has the potential to increase room brightness
and decrease window brightness.
Advanced Daylight in Take Sytstems
Light Shelves
Designed to provide sunlight in take and lead the sunlight
in to the floors, to provide diffuse lightning.
Main goal; taking optimum level of sunlight to illuminate
the interiors of the buildings. This illumination is provided
with small shelfs which act as an illumination source.
Basic Principles of Light shelves
Typical Light Shelf Sample
Light shelves can be used with artificial lights.
Light shelves can be used with artificial lights.
Light shelves interior
The positions of the light shelves, depend on the volume
of the spaces to provide indoor-outdoor relations and to
prevent glare. If the shelves are positioned far to ceiling,
more light can be taken.
Sometimes according to needs, solar light reflections are
used with artificial light sources, so same homogenous
lightning levels can be obtained at both day and nights.
Dynamic Light Shelves System
Shelves are movable so, direct light glare can be prevented and
also reaching of sunlight in to the deep of the room is provided.
Two groups;
 Manuel Systems: users arrange the positions of the shelves
according to seasons, months etc. according to the sun’s
 Automatic Systems: a micro computer arrange the positions and
angles of the shelves according to seasons to provide efficient
○ Disadvantages of this sytstem are cost expensive and needs more space
for technical staff. Also, it uses electrical components so there may be
some break downs in system.
Basic Principles of Dynamic Light Shelves
Two factors directly effect the positions and efficiency of light
 Climate
 Latitude and longitude coordinates of buildings
Day Light Transmitting Systems
are especially used in buildings that have insufficient or no
openings such as windows, skylight etc..
In light shelves, daylight is taken into interior directly, but in
transmitting systems, daylight is taken from one point, collected
and distributed to the spaces.
1- Light Tubes
emitting of daylight from one optical staff and transmitting
to the spaces.
This system is successful at especially deep spaces such
as large office buildings.
made up in three parts;
 Collector; positioned on rooftops. Hemi sphere shaped
optics or a tube take in or collects the daylight.
 Transmitter
 Distributer
Diagram of Light tube system.
Daylight in taking and illumination diagram
Compare with the light shelves, light tubes have more complex
mechanisms and they need more structural spaces such as small
skylight etc.
In spite of this when it is thought in a long term, light tubes can be
economic and effective for the wide and multiple spaces than the
light shelves.
Parts of typical Light tube system
Light Tubes on roof
Illumination with Light tube system
Polycarbon Optic Light Tubes
2- Fiber Optics
Fiber optics are, optical specified fibers that can transmit
and lead the light rays even through the long ranges.
Basic principle of fiber optic based lightning is close to the
light tube systems.
Solar panels or heliostatic units that are positioned on the
roof tops collect daylight that is transmitted with fiber optic
cables, then daylight is transmitted to light tubes. These
tubes are directly related with special lightning source to
illuminate the spaces at day times.
Solar panels or heliostatic units that are positioned on the roof tops
collect daylight that is transmitted with fiber optic cables, then daylight is
transmitted to light tubes. These tubes are directly related with special
lightning source to illuminate the spaces at day times.
Fiber optic daylight systems are more efficient than many daylight in take
systems. Also there is occurred less light losses so more daylight is
used for illumination as much as possible.
However, sensitive structures of fiber optic cables may occur some
problems and cost of treatment can be higher than the other systems.
Solar panels of fiber optic system
Illumination with fiber optic system
3- Anidolic Systems
Different from the light tubes, anidolic systems do not
collect the sun light.
Their work principle is; absorbing sunlight with a
glass semi optics unit than transmitting to the ceiling
system. In this system sunlight is transmitted directly,
there are no collectors, reflectors or mirrors.
Altough their simple mechanism anidolic systems
must be used with their special ceiling systems, for
this reason their field of use is limited and sometimes
that can be less economical than the other systems.
Altough their simple mechanism anidolic systems must be
used with their special ceiling systems, for this reason their
field of use is limited and sometimes that can be less
economical than the other systems.
Illumination principle of Anidolic system
Anidolic Sytem on the upper side of a window
4- Other Systems
Besides of commonly used daylight in take systems, also there are
new designed daylight in take systems that are used in sustainable
Some of them are;
 Holographic optic panels, prismatic panels, special glass types etc…
 Holographic panels are; carving of special designed textures to a laminated
glass with laser technology. These panels have specific features to emit sunlight
as much as possible. Holographic panels are assembled on the facades of the
buildings, they take the daylight with two ways and directly transmitted to ceiling
and illumination system.
As a light emitting system holographic panels are efficient, however
cladding of hole surfaces with these panels and maintenance problem
may limit the using of this system.
Prismatic featured panels, special glass panels have similar features
with holographic panels. They have same advantages or
disadvantages however many of types are suitable for using in hot
climate conditions.
Prismatic featured panels, special glass panels have similar
features with holographic panels. They have same advantages or
disadvantages however many of types are suitable for using in hot
climate conditions.
Holographic Panel
Prismatic Panel cladding