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Comparing light bulbs: upfront costs vs running costs

Posted by Cathy Debenham on 8 May 2012 at 9:10 am

Do you know the difference in annual energy costs of an LED (light emitting diode) lightbulb and a halogen bulb? You probably know that halogens are cheaper to buy, and more expensive to run, but do you know how great that difference is?

I didn't, until I visited the tp24 stand at Ecobuild this year. What would you guess? Twice as much? Five times? Ten times more expensive? Well double it. Yes, the cost of lighting your house with halogens is twenty times as much per year as the cost of lighting it with LEDs.

The difference is not as great with CFLs (compact fluorescent lamps) but it is still four and a half times cheaper.

There are three elements to take into account when you do these calculations. The upfront cost of the bulb; the cost of the electricity used to run it; and the life of the bulb. Incandescent and halogen lamps are much the cheapest to buy, but they fall down on everything else.

TP24 did its calculations based on a typical modern kitchen which would have 5 halogen lights. It compared the costs of these with the equivalent CFLs and LEDs. Its figures are based on the lights being on for 8 hours a day, 7 days a week for a year. I suspect that most of us don't have them on that much, but if you do the figures may prompt you to turn them off more!

The annual amount added to your electricity bill for running those five lamps would be £95.37 for halogen, £20.98 for CFL and £4.77 for LED. Add to that the fact that LEDs last for 20,000 hours, CFLs for 10,000 hours and halogens for just 1,000 hours and changing them rises speedily up the priority list.

The upfront costs for LEDs and CFLs are more: £9.95 for 5 halogen lamps; £24.96 for CFL and £34.92 for LED. But even at these prices, you're saving money six months after you've bought them. Click on the table above to enlarge it and see all the figures.

LEDs are increasing in performance at an incredible rate. Two years ago you could get 25-30 lumens per watt. Now they are generating between 65 and 100 lumens per watt. You may want to test one bulb to make sure you're happy with the light it gives before investing in large quantities. You can buy lamps that plug straight into the halogen fittings.

The one complication is if you have your existing halogens or incandescent bulbs on a dimmer switch. You can get dimmable LEDs, but they cost much more (between £20 and £45 each compared with £7 to £9 for standard LEDs). Alternatively you could get an electrician to change the switch to a simple on/off one.

More information about low energy lighting from YouGen

Low energy lighting information page  

How to choose the best low energy lights

Top tips for disposing of energy saving lightbulbs and other WEE

5 small tweaks to a greener (more efficient) lifestyle



If you have a question about anything in the above blog, please ask it in the comments section below.

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19 comments - read them below or add one

David Hoole

David HooleComment left on: 3 February 2015 at 9:24 am

Re typical lighting duration for calculation purposes. I also agree Adam's figure of 2.73 hours per day is probably more realistic than 8 hours, but every home varies in occupants' needs and how many occupants, and the natural light entering the building, so both figures are rather arbitrary. I note also that 2.73 x 365 days = 1000 hours per annum (well 996.45) which must surely be a simple 'industry standard'. I.E. a basic 1000 hour incandescent bulb would 'typically' last a year. Incidentally, the '1000 hour' bulb was a fix / con many years ago by the lighting manufacturers, before which, bulbs lasted longer than that ! So i think that's where the '2.73 hours per day' comes from, and it might not be accurate for your home.

The more you use your LED bulbs the greater the saving over other types, but the less you use them, the longer the payback time due to the higher upfront costs. So any exaggeration in hours of use gives a falsely high savings calculation for LED's, and vice versa for underestimates of lighting use.

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Cathy Debenham

Cathy DebenhamComment left on: 11 November 2013 at 9:12 am

@wakeywarrior I agree with you that Craiglights is wrong. I replaced the halogens in my bathroom with Aurora MR16 GU5.3 LED lamps, and they give a warmer light than the halogens. The electrician friend who recommended these ones brought one round for us to try before we replaced all of them. 

The key with choosing LEDs is that you have to consider the brightness and colour as outlined in this blog. The ones we've got are 3,000k, which is at the warmer end of the spectrum.

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wakeywarriorComment left on: 10 November 2013 at 1:32 pm

I think craiglights is wrong- I replaced all my LEDs with the Nexgen type from Simply LED and they are as good as the normal halogen ones, the generation 2 of these (ones I have) are £6.99 each.

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Caitlin Moran

Caitlin MoranComment left on: 18 September 2013 at 5:00 pm

Hi Craiglights,

Thanks for your comment, we will be revisiting this as it is an old blog.  Do let us know how you get on with your research.

Caitlin -The YouGen Team

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CraiglightsComment left on: 18 September 2013 at 3:56 pm


I work in the lighting world and frequently use dedicated LED modules that are fully integrated into fittings but only occasionally have call to use retrofit LED lamps like the ones you describe but recently I had been wondering about the actual cost difference between LED and halogen in a like for like swap over situation. Being to lazy to do the maths I thought google might have a pre made answer, which is where I found you.

I can’t believe how wrong your figures are!

£35 for 5 LED replacement lamps may well be possible, but I definitely would not want to live or work in a space lit by those nasty blue excuses for lighting, to get an MR16 LED replacement from a good manufacturer (like Soraa, Osram, Philips)from one of their ranges which will be at least close to a halogen lamps colour rendering you need to multiply that number by 3 or maybe even 4.

For halogen lamps you state £10 for 5 gets you 1000hrs, if you spend £20 on 5 good quality ones you can expect 5000hrs (or substantially more if you dim them by as little as 10%).

A good quality 50w halogen lamp will also put out somewhere in the region of 800 to 1600lm whereas a ’50 replacement’ LED lamp even by some of the better manufacturers will only manage 4-500lm at best so a 1 for 1 replacement wont always even be enough.

Also, add to all of that the various problems you will almost certainly have if you have a domestic dimmer.

I don’t doubt that there are savings to be made, and I am now more than ever going to be looking into the real costs of these options but for anyone else who stumbles upon this blog please take its figures with a big pinch of salt!


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InventoComment left on: 11 May 2012 at 11:27 pm

Hi Adam,
Your spreadsheet seems to be in about the right ballpark. In my experience, 4w is not quite equivalent to a 50w halogen. I used a four lamp unit in the kitchen as a testbed. First I bought 4 x 4w warm white but these were not bright enough. I then bought 4 x 5w Cree cool white. They were bright enough but I didn't like the harsh colour rendition. I then bought 4x 6w warm white and these were perfect and I've had them in over a year now.They are 360 lumen. Incidentally my daughter has recently bought an updated version at 5w and they are better with a 370 lumen output.

 There is plenty of the information you need as well as a cost saving calculator on the "simplyled" website. Her LEDs cost £12 with a discount for quantity.

Also, my lights are on 4-8 hours a day as the kitchen only has north facing windows, so I am already in profit.

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adamvaughanComment left on: 10 May 2012 at 10:08 am

Adam Vaughan here from the Guardian's environment site. Thanks for posting on this Cathy.

I'm in the process of swapping out halogens for LEDs at home, and am writing a piece for the paper/site on it.

By my calculations, you're in the black after 15 months. I've put my workings in a Google spreadsheet here: 

I'd be interested to see if my sums are similar to what other people looking at LEDs have come up with.

And also whether people have generally had a good/bad experience with switching to LEDs.

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MikelComment left on: 10 May 2012 at 9:42 am

Hi Invento,

Thank you for your comments. Yes, what you write is consistent with my own researches on the web. We do get glowing on one way switched circuits but less intense.  

With more and more of these LEDs being installed, I anticipate that others will raise this question. In an ideal world, we should expect to see updated wiring regulations and appropriate advice on mitigation.

Thank you for your reassurance that the glowing is not a problem. We have not had any difficulty. I'll add the caveat: so far!

Yes, I have seen these G4 LEDs. They would be suitable for the fittings under the kitchen units, where the LED bulb cannot be easily seen, but not for the living room because they are somewhat ugly in appearance. I take your point about the cooker hood and the transformer being inaccessible or difficult to replace.

 I think I'll have to accept that low energy LED lighting is a 'work in progress'.

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Cathy Debenham

Cathy DebenhamComment left on: 10 May 2012 at 9:20 am

Thank you for that, Adam. I think your 2.73 hours a day for the lights to be on is much more realistic for a domestic property than tp24's 8 hours a day. I'll be interested to hear how it goes.

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InventoComment left on: 9 May 2012 at 11:31 pm

Hi again Mikel,
Your G4 bulbs if they are 12v can be replaced with LEDs. Just search for "G4 LED 12v" on say Amazon. However, you will need the right transformer, see my 12:31 post below. You will of course need a separate transformer on each circuit. The oven light would be difficult as the transformer will be in the oven somewhere and will probably be unsuitable for LEDs.

PS to my previous post, the difference in glow brightness for the two switches is due to the different voltages induced in the supply cables from switch to light which will be different lengths. Shorter = dimmer.

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InventoComment left on: 9 May 2012 at 10:47 pm

Hi Mikel,
I have not seen the phenomenon of residual glowing of LEDs mainly because I do not have them on two way switches. My researches show that this is generally the cause. Apparently, the induced voltage between the live and switched live wires is enough to dimly light an LED as the wires are in the same cable and can run for a considerable length. There is a solution which involves wiring a resistor and capacitor across one of the lights, but I would not recommend it unless you were very confident at what you were doing. Apparently it is not a problem but may be an irritation. With other forms of lighting, it is there, but not noticeable.

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MikelComment left on: 9 May 2012 at 2:09 pm

In March we replaced all our 50w halogens (Gu10 and MR16) with 4w Gu10 LEDs, 39 in total. This entailed replacing the 27 existing downlighters with a metal cased downlighter (fire resistant and air leakage certified), replacing the 2 by 4 oversights fittings in the kitchen with 6 new down lighters and replacing the 6 240v halogens in the two bathrooms with 4w LEDs. The new downlighter casing were approx. £7 each. We removed the old MR16 transformers and replaced with 240v connections.

(At the same time, we took the opportunity to lag the pipes  in the loft and uprate the loft insulation. The whole job took about 4.5 days and cost about £1000. It is not simple to disaggregate the labour costs for the lights work from the insulation works.)

Our property is part modern (2007) and part older (1984). However, we have noted that some of the LED lights do not go out completely and there are residual voltages (range from 0+ to approx 40v) in the light circuits. This occurs in both the modern extension and the older part of the property.  It is more noticeable with the two-way switches that one way switches and curiously with the two-way switching the lights glow at different intensities depending on which of the two-way switches are used to turn on and off.

On researching on the Internet, we found that this is a known problem with LEDs glowing on switch off with a variety of explanations and no conclusive solutions.

My questions are whether others have also seen their LEDs not going out completely, whether anyone has found a solution, and whether there are going to be new electrical wiring regulations to deal with this problem? 

We also have some kitchen lights on G4 halogens (in the cooker hood and under the units) and our living room has a total on 33 G4 bulbs in wall and ceiling lights, a mixture of 10w and 20w bulbs. We have yet to find any suitable replacements for these both from a fitting perspective and an aesthetic perspective. We live quite a long way from any major shopping centre and it is not appropriate to buy living room light fittings over the Internet as we need to see the actual object.

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3coPeteComment left on: 9 May 2012 at 1:39 pm

I had an excellent experience with changing from 240v GU10 fit halogens to equivalent LEDs.  It was not until I fitted an 'Ecometer' and noticed that my 9 halogens were consuming c450w, they were very hot to touch so I assumed that was where all the energy was going.  I changed to 5w LED producing equivalent of c45w of light and my Ecometer barely registers the increase when lights are turned on.  The halogens give a not unpleasant sharp light which is very good in a kitchen so I selected the equivalent in LED rather than the 'soft white' light that is available.  In terms of lighting effectiveness, the equivalent LEDs that I have are not quite so good as the halogens but streets ahead of CFLs which we have elsewhere in the house.  It's a no brainer for me.


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InventoComment left on: 9 May 2012 at 12:43 pm

Sorry, MR12 should read MR16 but the edit does not seem to work.

Also here is a link to suitable dimmer switches


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InventoComment left on: 9 May 2012 at 12:31 pm

Hi Martin,

I am sorry you have had such a bad experience with LEDs, but it appears you have not done enough research. It is important that we get the facts right and do not put people off installing LEDs with horror stories about adding £50 per bulb for the circuitry! There is nothing wrong with the LEDs you have bought. For 12v LEDs (MR16) it is very important that you use the right transformer. It is no good just replacing your 12v halogens with LEDs and expecting them to work since the cheap transformers are designed to drive say 50w of halogen or more. Asking the transformer to drive say 5w to 25w of LEDs will immediately send it over voltage and blow the LEDs. Google "LED transformer" and you will find plenty of information such as . Here you will find that for £16 you can get a transformer that will drive all the LEDs you need,

For 240v LEDs, you can replace the GU10 halogens directly with no other considerations. The LEDs do not get particularly hot as they are only consuming say 5w and most of that is given out as light. However, if you want to dim these LEDs, it is important that you first of all buy dimmable LEDs and then a dimmer switch that is suitable. Most are not. Dimmable LEDs cost about an extra £1.

I have used both 12v and 240v LEDs for over a year now with no problems.

Caveat emptor.



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TheClimateGroupComment left on: 9 May 2012 at 11:37 am

Hey there,

Great article!

Sorry to jump in, but you may be interested in extending this convo by asking questions in a live Q&A we are running on Twitter tomorrow at 3pm with Harry Verharr of Philips Lighting?

The topic is 'the LED revolution' and you can ask any questions directly to Harry from 3pm, using the hashtag #CleanRevolution. 

You can also ask questions now, for Harry to pick up tomorrow afternoon. 

I hope it helps.  

Any questions, tweet me at @ClimateGroup.

Clare, The Climate Group 

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Cathy Debenham

Cathy DebenhamComment left on: 9 May 2012 at 10:32 am

I've done some more research:

For GU10 fittings (240v) it should be fine to just replace the halogen lamp with a LED. The early LEDs did have a problem with overheating, but the latest ones shouldn't.

MR16 fittings (12v with transformer) are more complicated. Whether a straight swap will work will depend on the rating of the transformer. If it is rated from 0+, then it's OK. If, say, it's rated from 50w - 100w, then it won't detect the 3w LEDs and will keep tripping out. 

As Martin says, the cost of replacing the transformer makes it uneconomic. It would probably be cheaper to get a new GU10 light fitting installed. It's also not always going to be easy to find the transformer and look to see what its rating is.

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Cathy Debenham

Cathy DebenhamComment left on: 9 May 2012 at 9:24 am

Thank you for your comment Martin. I'm going to do some more digging on this one, as advice seems to vary. I was quizzing an electrician on this last night, and he was saying the opposite of what you've heard - that you could just plug them straight into low voltage fittings. So I'm going to do more research and will come back to it soon.

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Martin Fodor

Martin FodorComment left on: 8 May 2012 at 1:09 pm

Would be helpful if you explain how much more complicated and expensive it can be to change to LEDs, though....

It  depends on the type of bulbs in particular; with low voltage (12v) halogens the simple replacement of like for like bulbs is unlikely to be successful, as I found out. The LEDs need a higher voltage and will also fail due to overheating. This means you need to remove low voltage circuits and revert to standard voltage type fittings, but at the same time replace fittings with ones designed to enable LEDs to dissipate heat, so I was told at EcoBuild and from suppliers. This puts the cost for replacement LEDs up a great deal - maybe £40-£50 extra per bulb.....

Therefore it's certainly not cost effective on a financial basis. Makes more sense if you are rewiring and updating lighting of course. But I'd certainly recommend against cutting holes in ceilings - it also makes upstairs rooms a source of heat loss from the room into a loft above that's really hard to insulate, of course.....

You can however now get some sensible LED fittings that simply replace a pendant ceiling fitting and allow a number of LED spots to be used within the room on various directional arms - much more sensible in my view.  

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