Change of Bulb

Incandescent lightbulbs or LEDs? Let’s put things into perspective.

Change of Bulb

Incandescent lightbulbs or LEDs? Let’s put things into perspective.

The whole question started when a lightbulb in my single-unit house went out. Being someone who’d only just started living alone recently, needless to say I was dead clueless as to how adulting works. Even the thought of changing my light bulb was nerve-wracking to say the least.

So there I was, standing in front of a huge shelf filled with lightbulbs. Rows and rows of bulbs, all in different shape and sizes. Bulbs in brands that I’d never heard of. Bulbs in shades of colour I didn’t even know existed. Bulbs of different types and wattages and socket-sizes and goodness knows what.

It was then that I realised, I probably should’ve researched a bit more before coming here.

Just when I thought things couldn’t get more complicated, I took a closer look and noticed the most surprising variation yet: some of them were actually priced differently.

Very differently.

I’m talking about a difference so substantial, I had to check whether the boxes had one bulb in them or three.


Turns out, the more expensive kind of bulbs were LEDs, or Light Emitting Diodes. They used a lighting mechanism very different from the normal “heat a wire till it glows” technique used in ordinary incandescent lightbulbs.

Were all these lightbulbs even compatible? What even was the shade of lighting I’d been having in my bathroom all this time? Is spending that much money on a LED worth it? I could have easily get three normal lightbulbs for the same price.

“One bad choice and I could end up burning the bulb — and the rest of my house with it”

I would be lying if I said the thought didn’t occur to me once. That one moment, however, was all it took for me to muster my courage and ask the staff for some suggestions. And right away, he escorted me to a section with light bulbs similar to my burnt one in terms of type and power rating.

I didn’t doubt his decision (not that I could afford to) just as how I didn’t want to end up burning down my place. Hence I left the shop with my brand new 45W bulb.

Based on the power rating, you can probably guess that it’s an incandescent light bulb, the traditional ones that appear in every light bulb clip art.

As despite me not questioning the shop for not introducing more of his store’s wide selection of light bulbs, I couldn’t help but wonder about the effect it has on my electricity consumption. It’s no coincidence that I ended up calculating and analysing my bills in the next few months. After all, it isn’t wise for a student living alone to spend unnecessary money on low-efficiency lighting, is it?

One thing led to another and I find myself learning more on how we consume electricity with all that lighting around us.


You’d be surprised by how rich the history of lightbulb really is. We have evolved from using the traditional and iconic incandescent lightbulb, to the more-evolved halogen lightbulb, and now finally to the glorified LED.

Fun fact to get things started: The brightness of a light bulb is measured by a unit called lumen. A nine-watt LED light bulb produce 450 lumens; so does a 45-watt incandescent light bulb. In other words, an LED can produce the same brightness as a incandescent one with five times less energy.


Unlike other technology, when it comes to switching to LED lightbulbs, things aren’t so straight forward. Even now, not everyone is on board with using LEDs.

It usually boils down to two reasons: high cost, and the fact that LEDs had trouble producing warm light. While you can get tiny LEDs for a few cents, the large kind used for house lighting used to cost ten times as much as an incandescent bulb. What’s more, because of the way they work, LED lightbulbs weren’t capable of producing warm light, which is what is preferred by lots of people.

As time progressed, LEDs became capable of doing more. Yet, there are still debates on whether changing all of our lightbulbs to LED can really save money and the environment. As usual, curiosity got the better of me, and so I began doing a simplified calculation on the environmental impact.

(I emphasize on the ‘simplified’ because I don’t take in account of things such as production waste, lifespan, and more. It isn’t going to change the calculation that drastically so it’s safe to ignore them for now in my opinion).

My big question was simple: Is changing to LEDs really helping to save the environment?


Let’s do a rough calculation. This is made under the assumption that all electricity is generated by fossil fuels or natural gas.

I know. Taking renewable energy into account is great and all, but from the way things are heading for our Earth (yes, I’m sceptical and can smell Armageddon a mile away) it’s probably safe to assume the worst for our planet.

First, let’s find out how much greenhouse gas is emitted when you use electricity. Greenhouse gas emissions are traditionally measured in terms of carbon dioxide (or CO₂) equivalent: in other words, the gases emitted have as much effect as a certain amount of CO₂. Electric consumption, on the other hand, is recorded by kilowatt-hours (kWh) which is basically the number of watts you were using multiplied by how long you were using it for.

Figuring out the exact numbers is much harder — or much easier, depending on how you look at it. A scouring of  the World Wide Web threw up so many answers, I didn’t know which to choose.

Each kWh of electricity you use consumes 726 grams, 830 grams, 512 grams, or 448 grams of CO₂ equivalent — depending on whether you ask Count Down Your Carbon, LEDone, Blue Sky Model or carbonfund.org. I know, right? It’s almost as hard as choosing the bulbs themselves.

But then, if you average it out, you realise it’s basically up in the upper 100s. And one of the prominent data in my opinion would be directly from the United States Environmental Protection Agency. According to them, the total emission for each electrical consumption is 707 grams per kWh.


Let’s be safe here, and assume something on the lower end of the scale — like 580 grams CO₂ per kWh, for instance.

Using this standards, we can calculate how much carbon a 40W bulb would emit in a year.

→ 40 watts

Let’s first calculate the amount of electrical consumed by that light bulb in the span of a year — measured in kilowatt hours, or kWh. Then, we’ll multiply that by the “carbon per kWh ratio” to get an estimate of carbon.

Let’s assume the light is left on for 6 hours each day. That’s a 40W bulb, left on for 6h.

→ 40 [W]
× 6 hours

Thus by multiplying that amount by 365 (days), we can roughly estimates the amount of electricity consumed annually.

→ 40 [W]
× 6 [h]
× 365 (days)

That gives 87,600 watt-hours, or 87.6 kWh. By multiplying that with 580 g/kWh — the carbon ratio we chose to work with earlier — we can calculate the total amount of carbon emitted annually by that single light bulb.

→ 40 [W]
× 6 [h]
× 365 (days)
÷ 1000 (watts→kilowatts)
× 580 g/kWh
= 50,808 g

That’s 50.8 kg of carbon a year, for a single bulb! In comparison, a 9-watt LED would emit about 11.4 kg. Just by switching to LED, we can potentially save up to 39 kg of carbon emissions each year.

Not to mention that there are others who rate incandescents as 60W and LED as low as 6W. In other words, the total annual emissions saved could’ve been very well over the 39 kg mark.


So how much would I actually save? Or, to put it more technically, how much is that 39 kg of carbon dioxide worth?

To put things into perspective, 39 kg of carbon dioxide accounts for sixteen litres of fuel consumed in a year, which means over a hundred kilometres of distance travelled in a car (depending on what sort of car you’re using, of course).

Imagine the amount of greenhouse gas emitted during a road trip. That’s how much switching to LED can save you over a year.

So depending on who you ask, this value might be translated differently. (Keep in mind that this is the value of one light bulb, which I’m sure isn’t enough to light the entire household)


Is there a point in changing to LED light bulb? My answer: Definitely; more than people had realized. But personally, I would rather focus on other electrical appliances that can do a better job than that.

How about keeping yourself warm with more clothes instead of blasting the heater? Or reducing your shower time by half? Even carpooling for just a week could save you that 39 kg of carbon. These ways aren’t exactly savvy but they do work better than spending a decade arguing which bulb is better. Even the act of switching off a light an hour earlier could make a huge difference, and I’m not just talking about carbon emission.

So what’s the point of all this calculating? Well, at the very least, now you know thing or two about light bulbs. Why not have a look at the one you have at home? Understanding how much electricity you’re consuming with each appliance might not just save the Earth, but at least it can potentially save you some extra change.

Remember, not everyone have the luxury to switch to LEDs, but we all can do a little something to save some electricity.

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