Electricity Saving Tips For Homes And Offices

LED lights: The material of LED lights affects the performance and life of LEDs

By on April 22, 2016

LED lights have become the talk of the hour today. And why not? LED lights are a tremendous alternative to the conventional incandescent lights that were being widely used until the arrival of the LED lights in the picture. LEDs have longer lives than incandescent lights. In fact, some LED types last for as long as 100000 hours (11 years and a half) compared to a very small life of an incandescent bulb. They are also more efficient as their consumption of electricity is lesser than the incandescent bulbs.

A major decision while buying LED lights

One’s biggest concern while buying a LED light, or any other appliance for that matter, is its life. “For how long this LED light function properly?” is a question which invariably pops up. Heat sinks of LED lights play a major role in the life of the LED light. Heat sinks are placed at the back of the LED lights. So one might also think, “Why do I have to bother about what’s at the back if I have my LEDs working properly?”

In fact, the thing which is at the back (heat sink), is the most important aspect of the lifetime of a LED light. The heat sink (or the material of the heat sink) directly affects the life of the LED light. Let us understand how.

Wastage of electrical power: LEDs vs incandescent bulbs

When electricity passes through a LED light, some of the electrical energy is converted to heat energy and a large part into the light energy. And in case of incandescent bulbs,only 10% electrical energy is converted to light energy and the rest of the energy is converted to heat.

This is quite undesirable as not only the electricity is wasted in the conversion of heat, but also the heat thus emitted is responsible for significantly reducing the efficiency of the LED light, that is, it reduces the ability of the LED to convert electrical power to visible light which is called luminous performance. It is measured in (lumens/watts).

Heat sink of a LED light

In order to arrest the decrease in the efficiency of LED lights caused due to the heat which is produced in the casing of the LED lights, heat sinks are used.

What is a heat sink?

You must have seen water sinks/basins in your bathroom. What do they do? They remove the excess water in the container thus facilitating a smooth and continuous flow of water in it. A heat sink works in a similar manner. A heat sink is something which acts as a sink to remove the heat from a system. So in a LED light, when heat is produced from the LED, the heat sink removes the heat from it thereby ensuring continuous removal of heat from the system and bettering the efficiency of the LED light.

Factors on which the performance of a heat sink depends

Since heat sink absorbs heat from the LED light and dissipates it outside, there are a couple of factors which effect the performance of a heat sink.

1. Size of the heat sink: Since heat transfer from the LED light to the surroundings take place at the heat sink, it is advised that the surface area of the heat sink is large. Higher surface area of a heat sink can be achieved by increasing the number of fins in the heat sink, or by increasing the overall size of the heat sink as well.

2. Finishing of the surface of the heat sink: If a heat sink with a painted surface is used, the amount of dissipation of heat is improved. This effect is even more pronounced when the transfer of heat is done by radiation of heat to the outside.

3. Orientation of the LED with respect to the heat sink: The orientation of the LED light source with respect to the heat sink also has an effect on the performance of the heat sink.

4. Material of the heat sink: This is one of the most important factors which is directly responsible for the performance of the heat sink. Let us try to understand how-

Material used to make a heat sink

A heat sink basically transfers/dissipates the heat from the heat from within the LED light source to the outside medium. It can do this in three ways:

1. Conduction (where heat is transferred from one solid medium to the other)

2. Convection (where heat is transferred from one solid to a moving fluid, for example-air)

3. Radiation (where heat transfer takes place between two objects having different surface temperatures)

Now the million dollar question: Which material should be used for heat sinks?

The material of the heat sink plays an instrumental role in determining the efficiency of a heat sink. This is because the thermal conductivity of the material that is being used to make the heat sink directly affects the dissipation capacity of the heat sink.

For such a role, one would like to go for something which has high thermal conductivity. Copper is an element which has very high thermal conductivity i.e. it is a good conductor of heat. But the demerit of using copper is it is quite expensive. Some people also use stainless steel for this purpose as it is thought that it does not corrode. But the problem with stainless steel is that it is not a good conductor of electricity, thereby is not a good choice.

Another choice for the material of the heat sink can be aluminium. It has a decent heat conduction capacity (better than stainless steel but lesser than copper) and is relatively inexpensive. In fact aluminium is the most commonly used material for making heat sinks as it is cheap as well as a good conductor. Most luminaries in the market have aluminium heat sinks. It is thus the most preferred material.

Thermoplastics is a new innovation in the field of heat sink materials. It is a specially engineered plastic which is a good conductor of heat and a low production cost. Although the conduction of heat in thermoplastics is not as high as it is in metals, but it is in accordance of the amount of heat produced in a LED system. In other words, it is well-suited for meeting the heat dissipation requirements of a LED light. In contrast to aluminium, the radiation ratio in thermoplastics is 7%-8% higher and the manufacturing cost in thermoplastics is 20%-30% lower. Please Note: Thermoplastics are different from regular plastics and regular plastics should not be used to make heat sinks as it will not provide good life to LEDs.

References:

http://www3.nd.edu/~leds/how/How.htm

http://www.lrc.rpi.edu/researchareas/leds.asp

http://www.lrc.rpi.edu/programs/solidstate/cr_thermalresistance.asp

http://en.wikipedia.org/wiki/Thermal_management_of_high-power_LEDs

http://www.ledinside.com/interview/2013/9/replacing_aluminum_with_thermoplastic_in_heat_sinks_cuts_cost_by_20_30

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  • Sushil Kumar Upadhyay

    Hello Abhishek,

    Greetings of the day. Thank you for helping us in selecting the best methods to save electricity and ultimately our money too :-)

    I want to know how do we decide or calculate the required lumens for a room/space. Is there a formula to look out for ?

    Thanks for your support and help in advance.

  • Harish Chandran

    Hi !! I am renovating an existing house and my primary aim is to make it energy efficient.. I have to say bijli bachao has been a guide to me for looking upon every product from an AC to a geyser..Now, I want to know whether Syska T5 Led tubes are good enough and whether 2 T5 Led tubes of 16W each can cover up a hall of say, 220 sq.ft or should i go for 3 ….The previous owner had used 3 Conventional Tube lights of 36W each…

    • Bijli Bachao Team

      Hi Harish,

      16W will be slightly less. Two 18W LED lights should be good enough for 220 sq ft room.

  • puja

    Hi!

    For my upcoming eye centre,
    My Reflected Ceiling Plan shows around 200 LEDS.
    Around 150 are 15 Watts, 6 inches,mPanel light
    40-50 2X2 Panel lights.

    Pl. advice me the brands with their cost , Life & replacement Policy.

    Is any manufacturer, providing more than 2 Years warranty?

    Thanks

    • Bijli Bachao Team

      Hi Puja,

      You should be able to get 3 years warranty from manufacturers. In fact if someone is using OSRAM LEDs, they may also give 5 year warranty. Other make are Samsung and Edison LEDs (and you can get 3 years warranty on them). Make sure that you ask them to show you LM-79 and LM-80 certifications for their products. Also please note, most sellers either get finished products from China or they get the LEDs from the makes I mentioned above and assemble it with India made drivers which are quite good. Branded ones may be costly, but you can even get good quality products from local manufacturers who use Osram, Samsung or Edison LEDs and have local manufactured drivers. Anyone who gives 3 years warranty would certainly use one of these. You can go through my own case study on this link: https://www.bijlibachao.com/lights/sharing-experience-of-buying-led-luminaire-for-a-residential-society.html

  • Dinesh Pal

    Hi I am planning to switch over to LED lights. I have some fittings which are installed on false ceiling. These are of specific size and I am told that entire fitting needs to be changed. Is this correct. Also which brand of LED is good. Philips, havelles, syska etc. Which one is better any recommendation.

    • Abhishek Jain

      Hello Mr Pal,

      That would be right. Most LED luminaires have their own fittings. Philips or havells would be good.

    • Prakash Thakkar

      Go for Teknolite. It is an Indian brand with factories all over India. They manufacture best in class LED lights and are a partner with EDISON LED. LED Lights with High Lumens. 2/3 Years Warranty. Call 9821024188

  • Neeraj Aswal

    Hi,

    I find information on bijlibachao very informative and useful. I’ve bought a new flat and soon going to shift there. I’ve selected geyser, AC and Fan after going through bijlibachao.com.

    One thing I’ve still not finalized is- LED lights. The problem is that my flat have 7 inch holes in ceiling for downlights whereas its very rear to get a good 7 inch downlight. Most of them are either 6 inch or 8 inch ones. So is there any way to fit smaller LED lights into such big holes without applying cement on ceiling?

    Thanks
    Neeraj

    • Abhishek Jain

      Hi Neeraj,

      I am glad that you found bijli bachao useful. Your steps towards efficiency help us achieve our objectives :).

      Frankly, it will be very difficult for me to respond to your query sitting remotely. You will have to work with your LED dealer and electrician to figure out if it would be possible to get something to fit in properly.

    • Neeraj Aswal

      Thanks Abhishek,

      I’ll try to figure it out and update it here if something useful (useful for others too) is found.

      I’ve shortlisted Syska DLC 6″ 15W (Deep downlight). But it seems to have too good to be true specs. Am I missing something? Will two such Downlights be enough for a 12×11 foot room? Is there anything better in performance and efficiency then this?

      BTW, are you planning any article on Electric Chimney too. What should be the selection criteria (other then price) for it?

      Regards
      Neeraj

    • Abhishek Jain

      Hi Neeraj,

      This light has about 1560 lumens output and two such light would be more than 3000 lumens which is more than enough for 12×11 room (it is in fact a little more than a regular tubelight). The beam angle is also 150 degrees so it is perfect for 12×11 room. You can certainly go for them.

      We do have Electric Chimney in plan but we do not have enough research on it yet to write about it.

    • Neeraj Aswal

      Thanks for such a quick reply Abhishek :)

      I’ll keep my eyes open for the new articles. Keep up the great work.

  • aastha bhandari

    Hi,

    I would like to explore an opportunity for one of my clients in the energy efficiency space.

    Do let me know who will be the right person to talk to at Bijli Bachao.

    Regards,
    Aastha

  • Avinash

    Why not give details of circuit inside the LED Bulb ? How 210 Volt AC is converted to a low Volt DC ? Is the Rectifier used has certain life and after that the LED buld becomes useless ? Almost all companies have started advertising LED bulbs but none have a BIS mark Why ? When is the right time to buy LED bulbs so that prices are stabilised !!!

    • Abhishek Jain

      Hi Avinash,

      At Bijli Bachao we intentionally try not getting into to much technical details, but we try to cover some basic things related to various appliances. We also try to keep it easy to understand. And that is why we have not given details of circuit.

      Prices of LEDs are quite lucrative these days. You just need to find the right vendor for it.

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