Efficient Lighting - Incandescent vs CFL vs LED

A typical household may spend 5-10 % energy into lighting. The ratio may get significantly lower during the summer months when the air-conditioning takes a major share of the energy consumption. It is important to know as well that more is the lighting load during air-conditioning; the more would be the air-conditioning load. There are many efficient lighting options available such as CFL / LED etc. Let us look a simple view of what efficient lighting means.

We have been traditionally using Incandescent Bulk. It has served well for more than 100 years. It is however an inefficient lighting device. It generates heat (heat gives light) and end up wasting 90 % energy as heat. Most of us have stopped buying incandescent bulk and rightly so. If we are still using an incandescent bulb, we should consider switching over sooner than later.


When we talk of energy efficient lighting, we have option of CFL (Compact Fluorescent Lamp) and LED (Light Emitting Diode).


Now is the time to introduce concept of Lumen. It is Lumens, not watts, which tell you how bright a light bulb is. The more lumens, the brighter is the light. Let us look at a simple comparison of the different types of lights and their lumens:


Incandescent Watts             

CFL Watts              

LED Watts              

Lumens (Brightness)



8 - 12

6 - 9

400 - 500


13 - 18

8 - 12.5

650 - 900

75 - 100

18 - 22


1100 - 1750


23 -30

16 - 20



30 - 55

25 - 28



* One can consider fluorescent tube light similar to CFL.


Clearly, CFL and LED are much more efficient than traditional incandescent bulbs.


There is another important consideration, which is the operating life of the bulb. A typical Incandescent bulks lasts for 2000 hours, CFL lasts for about 10,000 hours and LED lasts for about 25000-50000 hours.


CFL are significantly expensive and LED even more. However, the return on investment / pay back of CFL is about 2 years. It is no brainer that one mush use CFL or LED only now.


The question is when one should use LED or CFL. At the current costing, LED has a business case if the light has to be used say more than 18 hours in a day. Otherwise, one may continue with CFL and wait for LED comparative costs to come down further.


The biggest advantage which LED are bringing is in terms of controllability / remote controllability of the LED sights. That is expected to improve the financial attractiveness of LED. We would discuss the same in a future blog.


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