The Changing Face of Lighting

LEDs are changing the face of lighting

LEDs are changing the face of lighting

My first encounter with LEDs was for a school project where I wanted to use one as a little red indicator. In those days, they were simply Light-Emitting Diodes, nothing more. The though that they would, one day, be used as a source of light didn’t even remotely cross my mind.

In the last few years, however, LED technology has taken giant strides and the early problems like inaccurate colour rendition and a limited light-cone have been, to a great extent, sorted out. Added to that, the costs–which used to be very high–have come down to relatively affordable levels. While they are not, still, competitive with fluorescent lights, the day is probably not far when LEDs will replace them.  Even at today’s prices, they are already more economical in the long term.

With their small size and favourable physical properties—they run cool, have a long life and are able to vary their colour—LEDs have made it possible for lighting designers to come up with some very original creations.

Image derived from |

The Bottle Light

bottle light refractionSometimes, a simple idea can be immensely powerful. Maybe the bottle light is not something that makes a huge difference to your life or mine but, for those who live in shanties with little or no electricity, this is a godsend.

screencap from a BBC featureEssentially, one fills a used, transparent, plastic bottle with water and a little bleach (to prevent algae) and sticks it into a hole in the roof.  That’s it. Oh, and don’t forget to seal the edges of the hole.

The light that it produces is equivalent to a 50 or 60W bulb. Of course it won’t work at night but when you think of the dark homes that some of our less fortunate citizens live in, this can—at the very least—brighten up their day.

BBC News Magazine
A Liter of Light

Comparing LED & CFL Fittings

For the MChi interior site in Bombay (Mumbai), I found some really nice LED light fittings but they are more than three times the cost of identical CFL fittings. Now we all know that LEDs consume very little electricity  and they have an extremely long life but I wanted hard numbers to convince my clients – after all, they are the ones paying for everything.

It didn’t take long… At the light shop, it was pretty obvious that the 18W LED fitting threw as much light as an identical one housing 36W of CFLs.  Frankly I was a little surprised by the 1:2 power consumption ratio because I always assumed it was more like 2:3. However, LED technology is making such rapid strides that yesterday’s facts are already redundant. Putting all the costs into a spreadsheet immediately produced a very compelling argument in favour of the former.

An Example of Total Cost of Ownership – LED v/s CFL

While the life of an LED bulb is in the region of 50,000 hours, the calculation over such a long period (while in favour of LEDs) is rather unfair because even at 5 hours per day, that means 27 years.  Instead, I’m working with 30,000 hours which represents a more realistic 16 years.

Even accounting for the fact that the LED driver (an electronic device that regulates the power that LEDs receive) doesn’t have a 50,000 hour life, the calculation still showed a huge saving.

The calculations here are not likely to remain valid for long because the cost of power is sure to rise even further and that of LEDs can only go downwards.

Energy-Efficient Lighting

The incandescent bulb is the most common – and one of the least energy-efficient lighting options for brightening a space. Today we have numerous fluorescent type fittings; both, the old tubelight and modern compacts which retro-fit into incandescent holders. Light Emitting Diodes – LEDs – are rapidly getting cheaper and have now reached a level of affordability. The ways of lighting an interior or exterior space are numerous. We’ll touch on a few common ones here and see how they compare.


Apart from being free, studies have shown that natural light improves productivity and has significant health benefits compared to artificial light. Getting natural light into your home or office is not difficult to do – all it takes is a little planning by the architect at the design stage. It is necessary, of course, that the designer take care of glare and solar heat-gain but, once these factors are accounted for, there’s nothing better than sunshine to light up your life.

Unlike in Europe and North America, in peninsular India, light from the north-east is the best because it is glare-free. In fact, that’s why vastu stipulates that you put your study in that very corner of your house. Conversely, the south-west is where the glare is the worst, so it’s better to have shade giving trees to protect you on that side. If you are living in the extreme north of our country, however, where it is really cold in winter, you’d want to open out your southern side and achieve some heat gain. For the rest of us, reflected and indirect light is the best.

The mechanics of day lighting are more complicated and will, time-willing, have a page of their own but suffice to say that every architect should try to achieve adequate lighting without building up heat inside the building.

Tube Lights

Tubelights have been around for a while and, because of the harsh light they gave off in their early days, there are numerous people who detest their very existence. But tubelights are efficient and their colour temperature has improved dramatically in recent times which makes them as comfortable to use, if not more so, than an ordinary bulb.

Tubelights have a long life and their drawback, if any, it is that they require a bit of extra energy to start up. Newer electronic chokes have reduced this surge but it’s still often better to leave a tubeliight on than to turn it off and then re-start it within a few minutes.

Compact Fluorescent Lights (CFLs)

CFLs are the new tubelights – they have been squeezed and twisted so that they can replace ordinary bulbs. And they should! CFLs consume just 25% of the energy that a bulb does and are available in “soft white” which is easy on the eyes. Granted, they cost more, but the energy saved is more than paid back during its life which is 10 times as long as a bulb.


LEDs or Light Emitting Diodes are extremely energy efficient and should last for at least 10 years of continuous usage. They are becoming cheaper as production ramps up and the technology improves. They are still expensive when compared to the other forms of lighting but, as the comparison shows, that cost is more than paid back in the long term.

Efficiency Shootout

Here is a comparison that tells you approximately how much you benefit by installing fluorescent fittings or LEDs in place of incandescent ones. Note that the figures are approximate and likely to change as time goes by.

Cost Comparison over 10,000 hrs Usage Bulb CFL Tube LED
(a) Life of single bulb/tube (hrs) 1,000 10,000 2,000 25,000
(b) Number of bulbs/tubes required Nos. 10 1 5 1
(c) Cost of each bulb/tube (₹) 10 200 100 350
(d) Total cost of bulbs/tubes [(b) x (c)] (₹) 100 200 500 350
(e) Light Output [lumens per watt] (lm/W) 15 60 75 90
(f) Power requirement [equivalent to 100W bulb] (W) 100 25 20 15
(g) Electricity consumed (kWh) 1,000 250 200 150
(h) Running Cost [@ Rs. 5/kWh] (₹) 5,000 1,250 1,000 750
(i) Overall Cost [(d) + (h)] (₹) 5,100 1,450 1,200 1100
(j) Saving compared to ordinary bulb (₹) NA 3,650 3,900 4,000

As you can see, we can no longer say that the ordinary tubelight is still king. LEDs have a rated life of 25,000 hours although the drivers (transformers) will only last for half as long.  Like the new fluorescent fittings, they are usually available at colour temperatures that closely resembles daylight.

External Links

Philips India Lighting
Osram India
Havells Lighting
GE Asia Pacific


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We can easily save energy and reduce our energy consumption by taking a few simple steps. Most are not too expensive and they pay back fairly quickly.

Solar Hot Water

It’s one of the cheapest and simplest ways to save a huge amount of energy and the payback period is pretty short. The panels to be installed are basic and require very little maintenance. Essentially, the technology consists of nothing but copper pipes which zigzag behind a glass pane and heat the water that runs through them. This water is stored in an insulated tank so that if you wake up at the crack of dawn and try to have a bath, there’ll probably be some warm water for you to use. That’s if you didn’t use it up the previous night.
Continue Reading →

Passive Cooling in Tropical Climates

For centuries, until the invention of electricity, architects simply had to take into account the ways of the weather so that the interior of a home or workplace was comfortable for its tenants. In India, it led to the development of the Vastu Shastras – an ancient science that has now been obfuscated into a first class superstition… But that’s another story.
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Energy-Efficient Lighting

The incandescent bulb is the most common – and one of the most wasteful – ways of lighting a space. Today we have numerous fluorescent type fittings; both, the old tubelight as well as modern compacts which retro-fit into incandescent holders. Light Emitting Diodes – LEDs are rapidly getting cheaper and have now reached a level of affordability.
Continue Reading →

Star Rated Equipment

India’s Bureau of Energy Efficiency (BEE) has created a system of energy rating for a large range of appliances, equipment and light fixtures. Air-conditioners are, of course, the biggest guzzlers here and, while the initial expense is high if you choose, say, an inverter type, consistent use over time will more than offset the cost. BEE has created an interactive Energy Calculator to tell you how much you would save for different ratings of air conditioners.

Glass Façades in Tropical Climates

In our country today, glass-walled buildings are looked upon as indicative of progress and modernity and an international aesthetic. But the fallout of using such climatically inappropriate designs, is soaring energy consumption and sick-building syndrome.
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Fiber Optics for Accent Lighting

C|NET reports that a company based in Ohio, USA has created interior lighting systems that consume just one-third the energy compared to the average fluorescent system. In addition, it is said to emit neither heat nor UV light and won’t leak mercury if broken. Although the systems are expensive at the moment, they are expected to become affordable in the near future.

Okay, let’s be clear about how it works. What the system does is that it takes light from a conventional source – say an incandescent or a metal halide and distributes it via flexible plastic cables with optical fibre inside. This light is transferred to numerous “bulbs” which are naturally highly efficient given that there is no emission of heat at all.

Edit [27.09.2015]
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