Prof. Dr. Meltem YILMAZ
Introduction

As a day light intake system, light shelves can
be seen as more economical than the other
systems.

Their features are, their simplicity, ease of
applying to interior and exterior surfaces, ease
of dissembling can prove this theory.

However according to many sources, beside
economical and practical features of the light
shelves, their light intake factors can be limited
with the positions of the buildings and windows,
dimensions of the openings and the shelves.
the illuminance level differences with the use of light shelf
60
40cm; 53lux
illuminance level (lux)
50
40
30
lux
95cm; 25lux
20
10
150cm; 7lux
0
0
20
40
60
80
distance (cm)
100
120
140
160
To research the efficiency of the light shelves, single
storey small shed has been built. Shed has one door and
one window which is lead to the south. Dimensions of the
shed are; 240 cm x 500 cm x 220 cm and dimensions of
the window are 90x100 cm.
Construction of the demonstration shed
Construction of the demonstration shed-2
Also the distance between floor and window is 80 cm. After construction of
the shed, a light shelf has been applied to the window which is adjustable
and its dimensions are 50 x90 cm.

Measurements were taken in
May in different hours as 10:00
am and 11:30 am due to
determine effects of verticality
and horizontality of the sunlight
and try to provide correct
results. Illuminance level has
been measured with luxmetre
and as intensity factor lux
numbers were taken.
Researches were studied with
shelf and without shelf in
different hours to search out
the efficiency of light shelves.
Also intensity of the daylight
were measured on the floor
from the different distances
from 100 cm to 500 cm with
light shelf and without light
shelf in different hours.
Without Light Shelf
at 10 o’clock
According to the test
results; without light shelf,
at 10 o’clock intensity
level of the light from 100
cm to the window was
measured as 1284 lx.
From 300 cm distance
intensity of the light has
been measured as 480 lx,
and from 500 cm distance,
intensity of light has been
measured as 179 lx.These
measurements
explain
that, intensity of the light
decreases seven times
from 100 cm to 500 cm
without using light shelf.
Without Light Shelf
at 11.30 o’clock
To determine the vertical
effect of sun light, also at
11:30 same tests have
been done. From 100 cm
distance, 2010 lx has been
measured. From 300 cm,
704 lx and from 500 cm
258 lx have been
measured.



With Light Shelf
At 10 o’clock
These, measurements have
been retaken with the
horizontal positioned light
shelf. Dimension of the light
shelf was 50x90 cm and it
was made of steel with bright
surfaces to take in and reflect
more light. According to
measurements with the light
shelf; At 10 o’clock from 100
cm distance 1969 lx has been
measured, which was
approximately % 50 more
than the (without light shelf)
measurements. From 300 cm
662 lx and from 500 cm 245 lx
have been measured.
With Light Shelf
at 11.30 o’clock
To determine the vertical
effect of sun light, also at
11:30 same tests have
been done. From 100 cm
distance, 2310 lx has been
measured. From 300 cm,
922 lx and from 500 cm
345 lx have been
measured.

In the tests that are made
at 11:30 o’clock; From the
100 cm distance, 2310 lx
illuminance level has been
measured( 2010 lx without
light shelf). From the 300
cm distance 922 lx (without
light shelf 704) and from
the 500 cm distance 345 lx
(without light shelf 258 lx)
have been measured.
Results show that although
the vertical position of the
sun, light shelf can take
more daylight.
Illuminance level with and without light shelf Variation Factors at 10 o’clock
Illuminance level with and without light shelf Variation Factors at 11.30 o’clock
That means after 300 cm, effects of light shelf have
been decreased. Reason of this, due to opening
sizes, may be number of openings and dimension
of the light shelf. These measurements show that
although decreasing of illuminance level after the
300 cm, even a one window and a light shelf,
intensity of the sun light seems enough to provide
distinctive enlightenment.
To sum up; when the spaces and their openings are designed with
the optimum dimensions and ratios, light shelves can be efficient
for the extra lightning.
Test results show that; especially places where are close to the
window and light shelf, are taking more light than the other places
in the room. However, when the narrow shape of the
demonstration building and small window are considered,
especially after 300 cm distance, light intensity decreases.
This can be considered as a good result, because 300 cm is more
than the half of the building, and 500 cm is the end part of the
room.
As a result, light shelves can be very economical and
effective daylight intake systems; if the position of the
building leads to the correct sun position and if the buildings
and openings are designed with optimum dimensions.
THANK YOU VERY MUCH…