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Lighting Buildings

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by

Mina Kaboudarahangi

on 8 May 2014

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Transcript of Lighting Buildings

Lighting Buildings
by Dr.Mina Kaboudarahangi

Light & Form
Ambient lighting
Accent lighting
Task Lighting
Signage lighting
Light source beam spread
Light measurement
Lumen method calculations
Daylight Factor calculation
Ambient Lighting
is known as
general
lighting,
it radiates a
comfortable
level of
brightness
without glare
and allows you to see and walk
about safely
Task Lighting
task lighting is
focused on a specific area
to make the completion of visual tasks easier
it can make the work environment
more pleasant
Accent Lighting
it
emphasizes
on an area or an object in a room
This lighting
adds to the

drama or style of a room
by highlighting certain aspects of a room’s decoration
Decorative lighting
another way of enhancing the
b e a u t y
a n d character of the
building both interior a n d e x t e r i o r
Light Measurement
Light source beam spread
Common terms in selecting a light bulb are“
Flood
” light or “
Spot
” light
These are designations of beam angle
The beam angle is the
degree of width
that light comes from a light source
Typically a
narrow beam angle
is a
“spot”
of light and a
broader beam angle “floods”
an area with light, called a
flood light
There are a number of much more specific designations of beam angle
They are not used consistently between all the light bulb manufacturers, but several use this general terminology:
Narrow Spot :
5 – 15 degrees
Spot :
16 – 22 degrees
Narrow flood :
23 -32 degrees
Flood :
33 – 45 degrees
Wide flood :
45+ degrees
Natural Light
Daylight Factor the ratio of outside illuminance over inside illuminance, expressed in per cent
DF = (Ein / Eext)*100
Artificial Lighting Calculation
Lumen Method – determines
average light levels
in large open areas
Point Calculations – determines light levels at a
specific point
on an object or surface

we are interested to calculate illuminance level (lx or lm/m2)
what is Foot Candle?
One foot-candle is equal to one lumen per square foot (lm/ft2) or approximately 10.764 lux
for ease in calculation, 1 FC could be considered 10 Lux
1 foot candle (FC) = 1 Lumen (Lms) divided by 1 square foot (area / A)
1 FC = 1 LM ÷ A
Illuminance (E) (amount of light falling onto an object measured in foot candles) = Lumens divided by Area (in sq. ft.)
E = Lms ÷ A (sq. ft.)

Example:
calculate Illuminance(E) Level if;
Room 10’ x 15’
5 down lights
1000 Lumens each down light

E = Lms ÷ A
Illuminance = Lumens divided by Area
A = 10’ x 15’ = 150 sq. ft.
1000 Lumens x 5 down lights = 5000 lumens
E = 5000 Lms ÷ 150 sq. ft.
E = 37.5 Lms per sq. ft.
E = 37.% foot candles (FC)
Lumen Method
The quantity of light reaching a certain surface is usually the main consideration in designing a lighting system
This quantity of light is specified by illuminance measured in lux, and as this level varies across the working plane, an average figure is used
The Lumen Method is used to determine the number of lamps that should be installed for a given area or room
Example 1
• A production area in a factory measure 60
metres x 24 metres.
• Find the number of lamps required if each lamp
has a Lighting Design Lumen (LDL) output of
18,000 lumens
• The illumination required for the factory area is
200 lux
• Utilisation factor = 0.4
• Lamp Maintenance Factor = 0.75
N = ( 200 lux x 60m x 24m )
18,000 lumens x 0.4 x 0.75
• N = 53.33
• N = 54 lamps
http://studentnotes.co.uk/2360/lumen_method.php
UF is the
proportion
of the luminous flux emitted by the lamps which
reaches the working plane
. It is a
measure of the effectiveness
of the lighting scheme.

Factors that affect the value of UF are as follows:
(a) light output ratio of luminaire
(b) flux distribution of luminaire
(c) room proportions
(d) room reflectances
(e)
spacing/mounting height ratio

Spacing to Height ratio 
A drawing class 16 m × 11 m and 3 m high has a white ceiling and light-coloured walls.
The working plane is 0.85m above the floor. 5100 lm double-lamp luminaires are to be used and their normal spacing-to-height ratio
SHR is 1.75. (required illuminance for drawing class 600)
a) Calculate the number of luminaires needed
b) Sketch the layout arrangement of luminaires
c) Find the electrical power consumption of the lighting
system, if the electrical power consumption of each luminaire is 140 W.

Example:
H =(3 − 0.85) m=2.15 m
Room Index =3.3
From Table 3, for a room index of 3, utilization factor=79%=0.79
number of fittings=600× 16× 11 / 0.79 × 0.9×500= 29.12
The ratio of the spacing between rows to the height H above the working plane is:
SHR = S/H= 1.75
Therefore, S =1.75 H
=1.75 × 2.15 m
=3.76 m
Three rows of 10 luminaires are required, as shown in Fig. 1 giving 30 luminaires and a slightly increased illuminance

The electrical power consumption of each luminaire is 140 W. For the room the power consumption will be 30×140 W, that is, 4200 W, which is:
4200 W/16 m × 11 m
= 23.86 W/m2 floor area

This is not an end
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