This document focuses on the design and calculations of electrical lighting systems, emphasizing the importance of lighting in non-residential buildings. It discusses key concepts such as lumens, foot-candles, and lux, and outlines methods for calculating illuminance and the number of luminaires required for various spaces. Additionally, it provides guidelines and examples for effective lighting design using the lumen method and the Dialux software for planning lighting installations.

1. DESIGNING
FOR
MEGA
CONSTRUCTIONS
MODULE:-
ELECTRICAL LIGHTING SYSTEM
SUBMODULE:-
DESIGN AND CALCULATIONS
PREP BY:- MUSAIB UL HASSAN BHAT
ELECTRICAL DESIGN ENGINEER

2. “LIGHTING IS THE
LIFEBLOOD OF A
DESIGN”

3. • It is often desirable to calculate the amount of light that will result from a design. While seldom
required in residential design, lighting calculations are critical to the success of lighting designs in
most non-residential buildings: schools, offices, stores, and most other commercial and institutional
building types.
• In modern design, it is common to talk about foot-candles of light (or lux, if working metric) rather
carelessly. It is important to remember that the stated required number of foot-candles for a space
generally refers to the average light level requirement measured in the horizontal plane at desk
height. However, sometimes the criterion is for light only at the task or for light measured in the
vertical plane (as for artwork).
MODULE 2 :- ELECTRICAL LIGHTING CALCULATIONS

4. • The gross amount of light generated by a light source is measured in lumens. For instance, a candle
generates about 12.5 lumens of light. Foot-candles and lux measure the same thing the amount of
visible light that falls on a surface.
• The difference is that the foot-candle uses the Imperial standard measuring system (feet, pounds,
etc.), while the lux uses the metric system (meters, grams, etc.).
• A single foot-candle is equivalent to the amount of light that falls on a surface that is one foot away
from a single candle, and a lux is the amount of light that falls on a surface one meter away from a
candle. For conversion, 1 foot-candle = 10.764 lux.

5. Types of Lumens
 Raw Lumens: a measure of the theoretical output of a light. In the case of LED lights, this figure is
computed by multiplying the manufacturer’s lumen rating for the LED by the number of LEDs in the
light.
Raw Lumens are NOT representative of the actual light output because it does not take into account
the electrical and optical losses that impact all lights.
 Effective Lumens: a measure of the total power output of a light source.
The Effective Lumen output is measured using a photometric testing device and takes into
consideration electrical and optical losses, so it is a better representation of the useful visible light
that is produced.

6. Below are lumens for other common light sources: -
 Standard 60-watt incandescent lamp = 890 lumens
 Standard 18-watt compact fluorescent lamp = 1200 lumens
 Standard 4-foot-long T-8 fluorescent lamp = 2850 lumens
 Typical 100-watt high-pressure sodium streetlamp = 9500 lumens
 Typical 1500-watt metal halide lamp used in athletic stadiums = 165,000 lumens
• Some light sources use energy more efficiently than others. Note that the 18-watt CFL generates more
light than does the 60-watt incandescent Lamp. The essence of energy-efficient lighting is using light
sources like fluorescent lamps and LED’s that generate light with much less power than incandescent
lamps.
• Lumens are basic data used in several types of calculations. This information is vital to designing the
general or ambient lighting for a room.

7. Measuring Units of Light Level – Illuminance
• Illuminance is measured in foot candles (ftcd, fc, fcd) or lux (in the metric SI system). A foot candle is
actually one lumen of light density per square foot; one lux is one lumen per square meter.
• 1 lux = 1 lumen / sq meter = 0.0001 phot = 0.0929-foot candle (ftcd, fcd)
• 1 phot = 1 lumen / sq centimeter = 10000 lumens / sq meter = 10000 lux
• 1-foot candle (ftcd, fcd) = 1 lumen / sq ft = 10.752 lux
CRI: 50-80

8. Common and Recommended Light Levels Indoors
• The outdoor light level is approximately 10,000 lux on a clear day. In the building, in the
area closest to windows, the light level may be reduced to approximately 1,000 lux. In the
middle area it may be as low as 25 - 50 lux. Additional lighting equipment is often
necessary to compensate the low levels.
• Earlier it was common with light levels in the range 100 - 300 lux for normal activities.
Today the light level is more common in the range 500 - 1000 lux - depending on activity.
For precision and detailed works, the light level may even approach 1500 - 2000 lux.
• Generally, factors that affect the effectiveness of illumination are quantity and quality of
light, amount of flicker, amount of glare, contrast and shadows. Each factor must be
adjusted differently to optimize illumination in emergency, safety, operations, and security
situations, for instance.

9. The table below is a guide for recommended light level in different workspaces:

10. Public Space
Entrance Lobbies, Atria 200
Elevator Lobbies, Public Corridors 200
Ped. Tunnels and Bridges 200
Stairwells 200
Office Space
Normal work station space, open or closed offices, ADP Areas,
Training Rooms
500
Conference Rooms 300
Internal Corridors 200
Auditoria 150-200
Support Spaces
Toilets, Staff Locker Rooms 200
Storage Rooms, Janitors’ Closets 200
Electrical Rooms, Generator Rooms 200
Mechanical Rooms, Maintenance Shops 200
Communications Rooms, Loading Docks 200
Trash Rooms 200
Specialty Areas
Dining Areas 150- 200
Kitchens 500
Out leased Space, Physical Fitness Space, 500
Child Care Centers 500
Structured Parking, General Space 50
Structured Parking, Intersections 100

11. Calculating Illumination
Illumination can be calculated as
where
I = illumination (lux, lumen/m2)
Ll = lumens per lamp (lumen)
Cu = coefficient of utilization
LLF = light loss factor
Al = area per lamp (m2)
Example – Illumination
10 incandescent lamps of 500 W (10600 lumens per lamp) are used in an area of 50 m2. With Cu = 0.6 and
LLF = 0.8 illumination can be calculated as
I = 10 (10600 lumens) (0.6) (0.8) / (50 m2)
= 1018 lux
I = Ll Cu LLF / Al

12. Methods of Calculations:
The lighting system is one of the main systems in design, so calculations should be calculated to know how
to light the area required.
When designing lighting, you must make sure you have the proper amount of light. How many luminaires?
How many watts? Which lamp type? Keep in mind that the acceptable light level ranges from about two-
thirds to four-thirds of the target. This technical part of lighting design frustrates many architects and
interior designers.
There are two methods can be used in lighting calculations to determine type of lamps and luminaries used:
• Lumen method
• Packages " DIALux“

13. where
• E = the illuminance level is chosen after consideration of the IES code, the area is the working area to be illuminated, the
lumen output of each luminaire is that given in the manufacturer’s specification and may be found by reference tables.
• MF is maintenance or (the light loss LLF) factor: - This factor depends on the maintenance staff of the building, but in
general it is taken as 0.8 -0.9.
• Utilization factor (UF): - The light flux reaching the working plane is always less than the lumen output of the lamp since
some of the light is absorbed by the various surface textures. The method of calculating the utilization factor (UF) is
detailed in lighting design books, although lighting manufacturers’ catalogues give factors for standard conditions. The UF
is expressed as a number which is always less than unity; a typical value might be 0.9 for a modern office building.
THE LUMEN METHOD: -
This method is also called: Photometrical Computation and mostly used for interior lighting calculation.
To determine the total number of luminaires required to produce a given illuminance by the lumen method
we apply the following formula:

14. Example 1: -
It is proposed to illuminate an electronic workshop of dimensions 9 x 8 x3 m to an illuminance of 550 lx at
the bench level. The specification calls for luminaires having one 1500 mm 65 W fluorescent natural tube
with an initial output of 3700 lumens. Determine the number of luminaires required for this installation
when the UF and MF are 0.9 and 0.8, respectively.
The number of luminaires required (N)
Therefore 15 luminaires will be
required to illuminate this workshop
to a level of 550 lx

15. • Other factors that may be taken into consideration when using the lumen method are:
Room Index: this includes
Room dimensions:
• Length………….. (a)
• Width…………... (b)
• Height…………...(h)
Useful Height - Hk.
This can be calculated as:
hk = h- hd or hk = h-hd-hv ………. (1)
where:
hk = useful height
h = room height
hd = height of working area, usually taken as: 0.85 m
hv = height of illumination unit hanging from the ceiling, measured in (m).
hk = h- hd or hk = h-hd-hv ………. (1)

16. The reflection factor – ρ
This means the light reflected from ceilings, walls and floors which and depends on the colors, type of
floor and ceilings. Table -1 gives the reflection coefficient for various materials.

17. • For example, Table -2 below gives the
utilization factor UF for a fluorescent
luminaire with single 40W lamp and
prismatic diffuser 1300 mm length for
different values of the room reflection
coefficients: C – ceiling reflection, W-
wall reflection, F- floor reflection. If these
values are: (0.5, 0.5, 0.2) and the room
index is calculated to be 1.50, then the UF
= 0.52.
• Note: The reflection coefficients for a
standard room are: (0.7, 0.5, 0.2)
The reflection coefficients ρ can be used to determine the utilization factor UF for any luminaire from the
manufacturers catalogues when the room index is calculated.

18. Table below gives the maintenance factors for different types of rooms.

19. LIGHTING DESIGN USING THE LUMEN METHOD
The lighting installation may be designed using the following steps:-
1. Decide upon the illumination required in Lux Calculate the room index
2. Calculate the room index
3. Find the utilization factor for the luminaire to be used.
4. Assume a suitable maintenance factor
5. Calculate the number of fittings from lumen method of design formula
6. From corresponding standards list find the ratio of spacing to mounting height of fitting
7. Draw the layout of the fitting to a suitable scale.

20. Example 2: -
It is proposed to illuminate a class room of dimensions 6 x 8 x 2.85 m to an illuminance (E) of 400 lx at the
bench level. The specification calls for luminaires having one 1050 mm 40 W fluorescent natural tube with
an initial output of 3200 lumens with white metal base and prismatic plastic diffuser (its UF is given in
Table -2) . Determine the number of luminaires required for this installation when the MF is 0.7,
respectively. The reflection coefficients are: (C= 0.70, W= 0.3, F=0.2)
Solution: -
From the room dimension we can calculate the room index (k) assuming the working table height is 0.85 m.
Hence,
hk = 2.85-0.85 = 2m
Room Index = L x W / H ( L + W)
K = 6 x 8/ 2 x (6+8) = 1.71

21. • From Table -2, UF = 0.57
N = E x A / Lu x U x M
N= (400 x 48) / (3200 x 0.7 x 0.57) = 14.58 = 15
Since 15 luminaires are large number that can be installed in the ceiling, so we suggest to use luminaire
with 2x40 W fluorescent lamps with prismatic diffuser. Hence, the number of luminaires required will be,
15/2 = 7.5 = 8 Luminaires
Luminaires distribution:
Distance between two adjacent luminaire’s is

22. • Note: Usually we take the factor ½
when the dimensions of the room
are such that the ratio of the
length to the width is less than 1.6,
otherwise we take the factor of ⅓.
Distance between the luminaire and its adjacent wall = (½ to ⅓) x (room height):
Or 2.85 / 2 = 1.425 ≈ 1.50 m

23. EXAMPLE 3:
A general office measuring 15m x 9m x 3m high is to be illuminated to a design level of 400 lux using 85W
fluorescent fittings having a BZ classification of 3. The fittings are to be flush with the ceiling and the
working plane is to be 850mm above the floor. Design the lighting system for the office when the installed
flux is 8000 lumens per fitting.
Solution:-
The utilization factor can be found from manufacturers’ tables from the value of the room index. Height of
fitting above the working place (H) = 1.65
Room Index = L x W / H ( L + W)
= 15 x 9 / 1.65 ( 15 + 9) = 3.4
The utilization factor from the tables is found to be 0.56 and the maintenance factor of 0.8 may be assumed;

24. N = E x A / Lu x U x M
N = 400 x (15 x 9) 8000 x 0.56 x 0.8 = 15
In terms of illumination, 15 fittings would provide398 lux and would probably be satisfactory. In terms of
spacing, however, 16 fittings would be required which would provide the following illumination level;
E = 8000 x 16 x 0.56 x 0.8 15 x 9 = 424.77 lux
Spacing: The fittings have a BZ classification of 3 and therefore the maximum spacing to mounting height
ration is 1.25 : 1 (Refer to Table 1 for British zonal standards)
Mounting height = 3 m – 0.85 m (850mm) = 2.15m
Maximum spacing = 2.15 x 1.25 = 2.7 (approx.) – (center-to-center of fittings)
The distances of the fittings from the wall should not exceed half of the above spacing, and less if there is a
working surface near to the wall.

25. The maximum distance from the center of the fittings to the wall is therefore 2.7/2 = 1.35m.
Figure 1 shows one method of spacing of the fittings for the office.

26. EXAMPLE 4:-
An office 8m long by 7m long requires an illumination level of 400 lux on the working plane. It is
proposed to use 80 W fluorescent light fittings having a rated output of 7375 lumen each. Assuming a
utilization factor of 0.5 and a maintenance factor of 0.8, calculate the number of light fittings required.
So l: -
N = E x A / Lu x U x M
N = (400 x 8 x 7) / (7375 x 0.5 x 0.8)
N = 7.59 fitting ~ use 8 fittings

27. DIALux is continuously being developed by a team of 20. You can plan in DIALux with the
luminaires of the world's leading manufacturers and therefore have the greatest possible
freedom in the design process. And the list of international partner companies is getting
longer and longer.
Advantage of using DIALux
• Simple, effective and professional light planning
• Latest luminaire data of the world's leading manufacturers
• Latest state of the art software always available free of charge
• Energy evaluation at the drop of a hat
• Coloured light scenes with LED or other colour changing luminaires
• Planning whole buildings including outdoors spaces*
DIALux Light Software:

28. Flo w ch a rt f o r lig h t p la n n in g
Analysis of the planning objective
• Define the activities and different visual work that may be performed in the premises at different times of
the day.
• Define the lighting demands with regard to safety, visual needs and the visual experience.
• Examine the need for emergency lighting. Define the aims for energy consumption, environment and
maintenance of the lighting installation.
2. Analysis of planning conditions
• Define applicable provisions, standards, recommendations as well as special demands from the client and
users.
• Define the conditions for lighting the room, the type of workplace and its working area, etc.
• Investigate the conditions for the premises’ design, furnishings, type of monitors, flexibility, daylight and
the character of the premises.
• Establish the economic prerequisites for the installation and the maintenance conditions for the lighting
installation.

29. 3. Overall planning
• • Investigate the conditions for interaction between electric light and natural daylight.
Check the possibility of daylight screening.
• • Investigate which light sources, luminaires and lighting systems best satisfy the
demands aims and conditions.
• • Investigate the control possibilities for the lighting to increase comfort and improve
energy usage.
• • Investigate the overall co-ordination with other installations, color setting and
furnishings.

30. Overview of Lighting design and calculations using with DIALux Evo
This window will appear once we start the DIALux Evo
It depends on the situation about which
option is to selected to create a new project,
say for instance we have a floor plan with
us the we can simply choose “Import plan
or IFC” option.
And if we have no floor plan the we can
create a Room by clicking on “Room
Planning” option.

31. Set up the dimensions
Put the room type if you want to get the
recommended lighting levels as per EN12464
in Assessment zone and application.

32. Set up the room properties
Then there is the work of the creating the down ceiling, inserting the furniture and objects and then applying materials
and colors and these are as per the project requirements and properties of the room are important to calculate the
precise required Lux.

33. Inserting luminaires
All what was done earlier was in the construction mode, now go to light mode.
Data base
•Downloaded catalogues
•Online catalogues
We can have variety of the options for choosing the luminaires and we can use the online catalogue of
various lighting manufacturers found in DIALux Evo. List of various manufacturers can be found in
“Manufacturer” tab.
We can also download the catalogue any luminaires from the website directly and them import it into the
DIALux.

34. We have several websites that help us in choosing the desired type of Luminaire with ease e.g. LUMsearch

35. Once we select the particular
luminaire and it appears in the
Active Luminaire section, then it is
as per the situation what
arrangement of luminaire
distribution we select among the
ones present at left section entitled
“Luminaires”.
We can also have the distribution at
first in CAD as per our choice and
then just check the calculations in
the DIALux only. An if changes are
needed, we can re-distribute
luminaires accordingly.

36. C a lcula t ing a nd result s
Check the average Flux for each room and if needed different workspaces can be created in order to meet
the required Lux level in a particular zone of the area thus giving the design good efficiency.

37. Principles for establishing the working area and surrounding calculation surfaces

38. Report: - we then export the report for the lighting design having the details of different parameters.

39. After design is well enough and fulfills all the requirements as per standards, export the file as
AutoCAD file.

40. LinkedIn
linkedin.com/in/musaib-ul-hassan-
bhat-6a66a712a
Email
musaibulhassan@email.com
THANK
YOU