LdG-3 Lighting design Guide for LED

I will try my avoid scientific terms as mush as possible and I will do my best to make this Guide easy to understand

Introduction to LED

LED Technology is not new, as a matter of fact it is existing more than 50 years!

but what is new is the recent developments to make white LED from the Blue LED which was not existing at the beginning of first red LED .

also the recent developments includes the high efficient and long life time

Type of LED

First red LED was used in 1962

there are three main types of LED

  1. Low Power LED – e.g DIP LED (Dual In-line Package LED)
  2. Mid Power LED – e.g SMD LED (Surface Mounted Device LED)
  3. High Power LED-e.g COB LED (Chip On Board LED)
LED High power
High Power LED








This is the first LED and has been used for more than 50 years, it developed but still used in application when it is needed as indication not for illumination e.g in Traffic signal.

This slideshow requires JavaScript.

LED DIP for architectural Lighting

LED DIP is limited to be used as indicator not for illumination in architectural lighting as it has low power and relativity large size compared to other type of LED

This slideshow requires JavaScript.

Very Important Note

Many products available in the market suggest using LED DIP as replacement for conventional analogue lamp , I sugest avoiding using there types as they are not efficient, don’t provide enough Lumen (Light) , large and don’t look nice

Med Power-LED SMD

it much smaller and gives more light than LED DIP, the main application in cove lighting and strip light or diffuse downlight

This slideshow requires JavaScript.

the most comment strip light is LED SMD 5050 and LED SMD 3528 but there are many other types- the names comes from the size

SMD 5050 has a dimension of 5×5 mm while the name SMD 3528 has 3.5×2.8 mm

LED SMD 5050 LED SMD 3528
SMD 3528 VS SMD 5050

The main application of LED SMD Strip light is in the cove light and concealed light in architectural

for ambient light and General light COB is more economical , but for High end  application many manufactures use the multiple  Single LED and place in a board to have freedom for design of luminaries, at the end it is the choice of the luminaire manufacturer to deide which is better to design a certain luminaire


10_led COB
11 high power LED on one Circuit Board for one luminaire
one Array of LED COB for one luminaire


according to my experience, the COB makes the lamp big and the optics of lighting becomes big too making

  1. the luminaire bigger than when using group of individual LED High power
  2. the light is usually for ambient lighting and very difficult to find less than 10 degree as COB LED luminaire
13_led COB سبوت ليد
LED COD Downlight
14_led COB
ERCO Skim using High power on circuit board and lens to Make downlight very shallow and efficient
15_led COB Spotlight for Trak
High Power LED Spotlight usually smaller in single LEDs on CB with lenses
16_led COB Spotlight for Trak
COB LED Array makes spotlight bigger with limited light distribution

those are general guides ,but at the end as I mentioned earlier it is the final product to be evaluated not the source alone.


other types of LED

Technology is evolving and there are many types but I we mention the most common

Retrofit LED Lamps

retrofit are the easiest  way and most economical way to switch to LED and perhaps the most common one is the MR-16 Halogen lamp or what it is called in different market as QR-CBC 51 lamp with a lamp base of GU5.3

the advantage it is economical however the disadvantage

  1. it has lower life time
  2. less efficient than high power LED

my recommendation not to use this lamp in new project and consider replacing old luminaire when upgrading the lighting to the new High power LED

LED COG lamp

LED COG (Chip on Glass) are the replacement for incandescent lamp and it is main application on decorative chandelier


OLED has shorter life time at the time writhing this post and is very costly but technology is ruining fast , however the main application I can see as of current technology is mainly for diffuse lighting for decorative or ambient lighting where you need to see the source of light.

it has exceptionally very thin layer and could be promising in future for some application of architectural lighting.

Selecting and Specifying LED

LED characteristics and specification could vary from LED to anther ranging from very poor to excellent characteristics and the most famous LED manufacturers are


2- NICHIA (Japon),

3- OSRAM (Europe)

4- Philips – Lumileds (Europe)

5- Toyoda Gosei (Japon)

and some other

If you take one of the manufacturer e.g Cree you will find they have made many types more than 100!

Cree LED.png
only view type of Cree LED

each range has its specification and it is changing from year to another but there are general characteristics that help you specify LEDs

LED characteristics

  1. Efficiency -efficacy
  2. Color temperature
  3. CRI and color rendering
  4. SDCM or Macadam ellipse
  5. Spectral Power Distribution SPD
  6. Lumen Maintenance
  7. Failure Rate
  8. Damage Factor



To evaluate how efficient an LED is we use the term efficacy because it is not % it  is lumen/w or amount of light per one watt

efficacy is simply how mush lumen per watt (light) per watt an LED can give ,

the more lumen means more light for each watt

a typical value for 2016 could be higher than 120 Lumen/watt

11_led COB
2Watt LED gives 270 lumen the efficiency is 135 lumen/W

efficacy could be different for different color of light, usually the color the light the more efficient is.

Color Temperature

Correlated Color Temperature CCT for LED defines the color of the light and could range from 1800 to 10000 K

the lower the Temperature means warmer color


16_led COB درجة حرارة اللون ابيض اصفر ازرق  سبوت  ليد
2700K very Warm white ,while 6500K  is called Daylight and it is blueish white

17_led COB درجة حرارة اللون ابيض اصفر ازرق  سبوت  ليد

CRI and color rendering

The color rendering is the ability of a white light to render the color of objects , the higher the color the better to show the objects.

the current method use a number between 0-100 , the higher the number the better the CRI is

a good LED nowadays can easily have 90 CRI

19_led COB  ليد بدون محول color rendering index  سبوت  ليد

it should be noted that the Current method of 8 color or 14 color CRI is found not sufficient and not an ideal way to describe quality of color and the IES has proposed in 2015  a new method called IES Method for Evaluating Light Source Color Rendition TM-30-15


it is not yet adopted globally be seems to be mush more useful to the old 8 color method of CRI

it has Fidelity Index (Rf) , Gamut Index (Rg) and Garphs to show the color quality of a light source

SDCM or Macadam ellipse

SDCM (Standard Deviation Color Matching) or Macadam Ellipse is very important criteria

during manufacturing of LED  and applying phosphor coating it is very unlikely to get identical color but the color are very close some time you could see the difference between two colors by eyes and some other time is very difficult to see if there is any difference.

the measure that is used is the Macadam Ellipse which Group of color that are seen identical by human eyes even if they are technically different.

18_درجة أختلاف وتجانس لون الضوء للمبة الليد  SDCM.png
Macadam Ellipses group colors that are recognized identical by human eyes

19_درجة أختلاف وتجانس لون الضوء للمبة الليد  SDCM MacAdam ellipse.png


20_درجة أختلاف وتجانس لون الضوء للمبة الليد  SDCM MacAdam ellipse.png
When SDCM are higher than 3 then noticeable difference are visible especially when reflected by walls or ceiling

when you have SDCM<2 then the difference is not visible to human eye, and since many many manufacturer have this technology then it is very good to spasfiy SDCM<2

but also it should be maintained for long hours and after 50000 should not be more than 3


Spectral Power Distribution SPD

The light has 7 colors that you could see during the rainbow

similarly with any artificial light source it contains different power of colors represented in what is called SPD  (Spectral Power Distribution)

Spectral Power Distribution SPD.png
SPD for Sunlight, LED incandescent and CFL Lamp

As some manufacture try to improve some color to get better CRI like teh CFL you could get many spikes in some color , the less spikes the more natural the light is

This slideshow requires JavaScript.

Lumen Maintenance

a life time of LED is very long but what is more reverent and more useful is how is  lumen (light) is maintained by LED after certain time.

the most used method is IES LM80 and TM21 to determine the lumen after 50000Hour

Most LED manufacture mention the LxBy after 50000 and one of the very popular is L70B50 and L80B10

what dose it mean?

L70 after 50000h:

it means that 70% of the initial lumen is maintained


it means than 50% of the LED will have less lumen than the maintained lumen (Lx)

L70B50 after 50000 h:

it means 50% of the LED are maintaining the 70% of initial lumen after 50000 hours


L80B10 after 50000 h:

it means 90% of the LED are maintaining 80% of the initial lumen and 10% is not after 50000 hours

the higher the L and lower the B is good but make sure these values are given after at least 50000 hours as some manufacturer give better number but only after 25000 hours not 50000 hours!

what dose 50000 hours means in years:

LED L80 B10 50000 hours in years

Failure Rate

Lumen maintenance is different than total failure some manufacturer give this as percentage 10% or less for 50000 hours , the lower the number of course is better .

Damage Factor

it simply means how LED could damage sensitive art and this probably only important in museum and gallery where very sensitive art is being exposed to light

LED in general is better that Halogen and HIT but it is very important to ask for the value of damage factor for the LED

good value that was published by ERCO is Damage factor 0.149 mW/lumen which is lower than halogen.

That was specification of LED but what about LED luminaire

An LED luminaire has mush more than LED!

it has

  1. The LED
  2. Heat dissipation system
  3. Control Gear or Driver
  4. Optical System
  5. Other Mechanical system for some protection like IP


LED Cree ليد لايت لمبة لمبات سبوت جاون سقف جهاز
Downlight with LED, Heat Sink , Driver and optical system

How to specify those

Heat dissipation system

The Heat-sink is very important as it helps ruining the LED for its lifetime and ensuring maximum efficiency

There are many types- basically heat sink could be passive or active

The active heat sink uses the fan to cool the LED while the passive heat sink use metal like aluminium to cool the LED.

ليد المبدد الحراري القسري  مع مروحة

Active Heat Sink with Fan

المبدد الحراري الثابت بدون مروحة المنيوم حديد ليد
Passive Heat Sink


Personally i prefer the passive as it is very difficult to get the fan run for more than 50000 hours. also if the fan fails the LED would have shorter life time. however there could be some application where you don’t need the 50000h like shops and retail.

Control Gear/LED Driver

LED Driver help supply the LED with the right current.

each Driver has certain capacity in Watt and input as well output

LED runs at different currents depends on manufacturing and heat management, the lower the current usually the more efficient the LED is while the higher the current the more cost effective is.

the most common current to drive LED is

350 mA




LED Driver has to be selected to match the LED luminaire manufacturer , some manufacturer they supply the complete luminaire with driver some other supply without driver.

to select the right one you should select the right mA, Watt

Type of Drivers

There are many types to control or dim the LED , the most common ones are

1-Switchable Driver

2-Phase Dimmable Driver

3-0-10 Volt Dimmable Driver

4-DALI Dimmable Driver

Switchable LED Driver

They only switch LED on/off

is economical solution but limited in controlling the light

LED Phase Dimmable Driver

this could be controlled by the same way as halogen and incandescent lamps

the disadvantage that not compatible with all dimmer in the market you have to make sure that the dimmer is made to dim LED type.

0-10 Volt Dimmable Driver

This is better in terms of compatibly with LED , it is controlling the driver by 2 wires different than the power line unlike the first option


  1. as the wires diming the LED are different from the Power then no issue with dimming .
  2. could be easily connected with smart system like KNX.


  1. has limitation as you have to define the luminaires that will be dimmed together before wiring.
  2. it uses a lot of lines for each group of luminaires, you need separate wire e.g if there is 5 rooms in each rooms there is 3 group of luminaires to be controlled speratlly then you need 15 pairs of wires for the five rooms.

1 10 Volt 1 10 فولت ربط التوصيل.png


This is the most flexible driver

the DALI (Digital Addressable Light Interface) driver is smart driver that receive and send information through a wire to the controller


  1. one wire can connect 64 driver to the controller  eg if there is 5 rooms in each 3 groups you only need one pair of wire to the controller.
  2. High flexibility since you can decide after installation which luminaire should be dimmed , it could be programmed any time by the installer or technician.
  3. you need only one controller per 64 driver.
  4. excellent for connection with smart system like KNX


  1. The driver has more cost compered to the other drivers, but with good design the system could be less expensive as it have less wires and controllers, it really depends on the situation.



توصيل اسلاك نظام دالي DALI.png
DALI needs only one pair of wire between the luminaries and the controller



Method of Dimming LED

there are two types of dimming LED PWM and CCR

PWM Pulse Width Modulation

طريقة التخفيض بتعديل عرض النبضة Pulse Width Modulation (PWM) LED ليد

in PWM the light is reduced by reducing the with of the plus


the LED color will not be changed


is not suitable for Video conferencing as you could see the light is moving and not stable, Human eye cannot see this frequency but the camera dose


CCR Constant Current Regulation

ليد طريقة التخفيض بتنظيم تيار ثابت Constant Current Reduction (CCR LED

in this method the light is reduced by reducing the current


the light color could change slightly but it is unlikely  noticeable


very good for video recording

I would recommend the CCR since nowadays every almost one is recording video at least with mobile phone!

Optical System

the optical system of LED control the light

Optical System For mid power LED

it is mostly diffusers

انارة ليد ال اي دي مع بروفايل شريحة المنيوم وناشر للضوء.png
Diffusers and metal channel for the LED SMD

there are many types of accessories to help hold and control the light of LED SMD

انارة ليد ال اي دي مع بروفايل شريحة المنيوم وناشر للضوء زاية.png
Channel for corners for SMD 5050

Also there many  types of diffusers e.g clear, Opal

usually the more uniform the light the less light output the diffuser will get


these channel help installing the LED strips inside architectural details like floor or shelfs

the designer should select the right type and ensure proper coordination with architectural details


Optical System For High power LED

mainly lenses or reflector to control the light of High power LED

لمبة ليد عدسة عدسات.png
Different Lenses to control the light of High power LED


عاكس عواكس ليد ال اي دي.png
Reflectors to control the light of LED especially the LED COB array

This slideshow requires JavaScript.

To see the application of different beam angle you can see the LdG-2


Lighting design LdG + LdC Page

LDG and LDC-2

if you are intersected  in  learning lighting design software then you can visit this  page

DIALux evo Tutorials

27 thoughts on “LdG-3 Lighting design Guide for LED

  1. ibtahim abdel hafez February 13, 2016 — 2:24 am


    Liked by 1 person

  2. Very impressive text. Thanks

    Liked by 1 person

  3. Super nice ezzat! Keep going with it! BEST REGARDS MY FRIEND!

    Liked by 1 person

  4. Very Nice and easy to understand explanation!Thanks Ezzat for it….Keep it up.

    Liked by 1 person

  5. Debabrata Sarkhel February 13, 2016 — 1:30 pm

    Very good write up…informative…excellent!!

    Liked by 1 person

  6. Excellent!

    Liked by 1 person

  7. A very well written blog, lot of information about LEDs

    Liked by 1 person

  8. Great Job thanks.

    Liked by 1 person

  9. I liked that it gave a broad brief and informative description . Well done.

    Liked by 1 person

  10. Thank you for a great job.

    Liked by 1 person

  11. I consider this a valuable resource tool that I can share with my clients!! Outstanding Job! Concise and pragmatic

    Liked by 1 person

  12. Michael Wenceslao February 19, 2016 — 5:57 am

    Very informative and useful

    Liked by 1 person

  13. extra and Very informative and useful thanks for this great job

    Liked by 1 person

  14. Very informative and useful

    Liked by 1 person

  15. The B10 statement is misleading. B50 forms part of the “rated median useful life” whereas B10 refers to the “useful life”. The B10 claim is based upon the performance of a very small number of the test batch of LED, 1 LED in 10 as opposed to 5 LED in every 10 for B50. This results in a higher possibility of errors in the statistical modelling. Hence claims that B10 offers lower risk for an installation may be misleading. In summary beware of manufacturers quoting B10, it is not as good as it seems

    Liked by 1 person

  16. Great job, perfect information to share with our clients. Thanks

    Liked by 1 person

  17. Good job Ezzat, your posts are very informative and the tutorials are very helping

    Liked by 1 person

  18. very informative. all in one page

    Liked by 1 person

  19. Salam Thank you for the led information as you mention not most the light shop have the back ground in led or the size of lamp you should use I am in dammam Saudi Arabia , led comes in different power like 110 to 240 or 220 only In my home I have to power 110 and 220 . My you can help me I have setting area size of 8.4 m by 3.20m in celling h about 2.70m I opened 8hole of 3inch in both side for led and also I install strip line light around the border as hidden led Can you help me to chose which led light can I use and strip line led Thank you

    Sent from my iPad


    Liked by 1 person

  20. Thanks for Posting regarding Led Blog. We are also wholesaler of Led Light in India


    1. We are a supplier of LED, looking for an association.

      1. Yes, we are always looking for the best LED and partner. I would need more information and pricing to see if we are a good fit.

        Liked by 1 person

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this:
search previous next tag category expand menu location phone mail time cart zoom edit close