WORLD OF FIGURES: State should ban filament light bulbs in favour of LEDs

In September 2013 (slightly over five years ago), I worked out that a compact fluorescent light bulb (CFL) would pay back its purchase price in about three months through savings in energy costs.

At the time, the price of a CFL was about Sh200, which was about seven times that of an ordinary filament lamp (Sh30).

But things have changed quite a lot since 2013.

These days, energy-saving bulbs in the market are no longer the CFL type. Although CFLs are still available, they have gradually been replaced by the light emitting diode (LED) technology.

While CFLs consume about 20 per cent of the energy of filament bulbs, LEDs are even more efficient at just over 10 per cent. To get the same brightness as the popular 60W filament light, you need a 13W CFL or a 7W LED bulb.

BIG DIFFERENCE

With such a big difference, it is surprising that filament bulbs are still readily available in the shops. Imagine if some one invented a car that drives for 100km per litre of petrol while our ordinary ones do about 10km?

How long would it take before ordinary engines disappeared from the market? I suspect that governments would put out regulations banning the use of ordinary cars in an effort to save their economies from high fuel prices.

Why is this not happening in the electricity sector?

Initially, LED light bulbs were very expensive. I saw some going for over Sh600 each five years ago. But today the situation has changed.

I recently bought one (made by one of the largest bulb manufacturers in the world) for just Sh200.

It was a 7W LED that has the same brightness as a 60W filament type. I fitted it at a place that needs continuous light from 7pm to 11pm every day.

That is four hours daily. How many units of electricity will I save?

A 60W filament bulb running for 4h consumes 4x60/1,000 = 0.24kWh. The new LED will consume 4x7/1,000 = 0.028kWh. So, I will save 0.212kWh every day.

Now, I paid Sh200 for the LED light instead of Sh40 for the filament. That is, I spent an extra Sh160 for the LED. So, the next question is: how long will the LED take to recover the extra cost?

According to my current electricity bill, I consumed 258kWh last month and these will cost me a total of Sh5,786. Thus, I am paying about Sh22.43 per kWh.

Therefore, by saving 0.212kWh of energy, I am reducing my lighting cost by Sh4.74 each day. At this rate, I will recover the extra Sh160 paid for the LED in about 34 days — one month!

And that’s not the end of it: a filament bulb runs for about 1,000h before burning out. The LED says it will run for 25,000h — 25 times longer. While the 60W filament lasts about eight months, the LED should do over 16 years!

So, again I wonder: why are we still buying filament bulbs? The government should ban their use!

www.figures.co.ke twitter: @mungaikihanya