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Energy saving light bulbs – turned off by slow light-up times?

Energy saving light bulbs

Are you turned off by the sluggish light-up times of energy saving light bulbs? Our latest lab test results suggest that this problem may be fading, but it all depends on how good the bulb is.

The most common type of energy saving light bulb, compact fluorescent lamps (CFLs), have been plagued by frustratingly slow warm-up times in the past – as many of you have shared in previous light bulb-themed Conversations.

The bulb in my bathroom is one such excruciating example. During the mini-test I conducted last night, it was over a minute before it emitted anything more than a dull orangey light.

Our rather more scientific, lab-based test findings, however, do make for better reading. The top performing CFLs are brighter, able to withstand being switched on and off 30,000 times and give out a fair amount of light immediately after start-up.

LED bulbs still king

During our tests, we checked how bright the bulbs were when first turned on, and then at intervals to ensure measured brightness met what was promised on the packaging. Our Best Buy CFL light bulbs didn’t drastically dim after 5,000 hours – the equivalent of five years’ use – and emitted good levels of light.

Start-up times still aren’t great, though. The worst performer emitted no light at all after three seconds. And even the best CFLs only achieved less than half their claimed brightness when they were first switched on.

For instant bright light, you’ll need to turn to more advanced LED lighting – but be prepared to pay a premium for it.

How much for a light bulb?!

The two LED light bulbs we tested were in a league of their own when it came to efficiency and providing immediate light.

But you’ll have to shell out at least £20 – and for one, nearly £40! – to bask in the LED radiance of these bulbs. Energy efficiency savings aside, that’s a lot of upfront cash to shell out on a single light bulb, particularly when we’ve become used to the likes of cheap ‘three-for-a-pound’ supermarket offers.

Your light bulb bugbears

Overall, it looks like energy saving light bulb technology has improved and it’s good to see more candle and rounded bulb-shape varieties available too.

Yet, as the next phase-out stage for 60W traditional light bulbs beckons, other small but significant daily usage problems remain for many of us – like the potential incompatibility problems posed by dimmer or timer switches, for example.

Personally speaking, until the price of LED light bulbs come down, it looks like I’ll have to wait for my CFL light to fully kick in after switching it on. Though I’ll certainly be pickier when I have to choose a replacement. Are you willing to pay more to enjoy instant, long-lasting light?

If you’re a Which? member, you can view the full test results of our Best Buy light bulbs here.


Sadly I find the Which? Report really inadequate in several respects. The basic Which? view of the light bulb seems to be that you turn it on, it doesn’t really matter if it takes a few seconds to get going and then you leave it on for a long period. Many lightbulbs in fact are used on for a brief time: Security lights, light in a toilet (we men can often finish our business long before the light allows you to see what you’re doing), light in a room on for the 30 seconds it might take for you just to pop in to pick something up, etc. Here the warmup time which can be surprisingly protracted is a major problem, particularly when what light is produced tends to be at the red end of the spectrum making effective visibility much poorer. The measured light level may come out to be quite high since using broad-spectrum photometric measurements things look much better than they are if you use a measurement at the middle of the spectral band (green light, where our eyes have maximum sensitivity).
The second problem I have is that if I check low-energy lightbulbs for the light output in green and compare that with old-fashioned tungsten lightbulbs then they generally produce about 15% less light than you would expect from their wattage marking (so you get about 50 W out of a 60 W marked long life bulb).
There is one way out of this which I do not think as mentioned and this is to use halogen lightbulbs which turn on instantly but use a relatively high amount of power, are also very expensive and seemed to last even fewer hours than the old-fashioned tungsten lightbulbs.

Low-power lightbulbs are one of the major technological defeats of recent years. Homoeopathy may be popular but lightbulbs producing homoeopathic levels of light are simply not fit for purpose.

How much light do you need to go for a pee? I’ve got one of the freebe CFLs in our smallest room, and at 7W it’s probably brighter than actually needed, but is still 1/5 of the cost to run than the standard 40W Tungsten that I took out.

Although at first on, it’s probably only equivalent to a 40W, before getting to it’s full 60W equivalency; exactly how bright do you need it?!

Or, put another way, if you’re in the ‘reading’ room for more than a minute, the CFL is nearly up to full brightness; perfect for that monthly computer mag…

PerryM says:
11 July 2011

Keep a lookout in Lidl for LED ‘bulbs’ – I’ve bought several ‘spotlight’ types over the last year or two for less than a tenner each and they are all working fine with no apparent intereference problems. One is in my bedside light and provides the only light for reading, so I think I would have noticed any adverse strobing effects. I do know from my job as a video engineer that this is very subjective to the individual.
I also know from my video experience that neither LED or CFL lamps will match tungsten for best colour rendering, faces in particular will always be unflattered by the light they produce.

IanP says:
11 July 2011

Where you are coming from Stan Jacos? You are advising the use of candles when everyone knows that they can cause fire. That’s irresponsible! And you will be telling us next that cooking with microwaves is safe. The Russians banned it 40 years ago!

I am being very polite when I say that you have managed to get every single point in your post WRONG! First of all its “stanjackos” not “stanjacos” (You need better glasses). Secondly, the comment which refers to using wooden tools and candles went straight over your head. It was a a sarcastic comment refering to the fact that nearly everything in the modern house can be harmfull to your health in a cumulative way (even microwaves), ergo, anybody who worries about the minute danger posed by CFLs are paranoid and should eliminate everything that contains hazardous materials or functions. It was an hypothetical comment that I assumed anybody with more than 2 brain cells would understand. Obviously I was wrong. Thirdly, you are totally incorrect when you say that the Russians banned Microwaves 40 years ago, Micowaves were indeed banned in 1976 (35 Years ago) on information based on flawed research. This ban was lifted after Perestroika in the late 80′s and microwaves are now widely used in Russia.

Finally, candles are not dangerous, they are inert cylinders of parrafin wax with a vegatable based wick. It is the careless and foolhardy that cause problems not the candles.

Gidster says:
11 July 2011

I am afraid I still don’t understand whether it is more cost effective to buy LED ceiling spots(compared to ‘regular’ 50w Halogens)? I have a lot of these ceiling down lights and I would really love to know if it will pay us to switch over to LED now in total (ie a big bang changeover) or only as and when the Halogens fail. Or even, dare I say it, at all! Clearly at £1 or so for a Halogen compared to £12 – £14 for an LED there is an immediate difference in the puchase prices. But as the LEDS run at 7w compared to the 50w GU10 Halogens I wonder how many hours of the light being on do you need to reach the breakeven point? And of course there is the fact that at 50,000 hours of predicted life for an LED you should not have to replace them as much as the 1,000 hour Halogens. Can anyone not related to an LED light company tell me the payback time of these LED lights?
Many thanks!

I’ll try and take up that one; I don’t work for an LED company! Let’s make this one difficult for the LEDs while we’re at it; don’t want to be accused of swaying the figures like an advertiser!

Firstly, I think your prices are a little harsh with the LEDs a (ours were £10) and £1 for a GU10 50W a little cheap, but i’ll use your figures anyway (you may buy in bulk).

50,000 hours for an LED is also going some. So let’s call it 20,000 in the real on/off world. And 1000 hours is half of the length of hours that I saw advertised on the Halogens I used to buy, even though they never used to last a year, but I’ll use 2000 hours to make it a challenge (let’s see who still complains!)

Right off the bat the LEDs last 10 times longer than the ‘equivalent’ Halogens, leaving you with £4 to find before making a saving on by buying a £14 LED.

Then at 12p per KWh of leccy over 20000 hours you get:
LED – 20000h x 7W = 140KWh x 12p = £16.80 over it’s life.
Halogen – 20000 x 50W = 1000KWh x 12p = £120 over 10 lives…


And how many of these horrible things did you say you had!?

Now the biggest hassle for LEDs is that you can’t easily dim them, but at a cost of about £40 a light with the correct fitting, you can, and with a good wide beam, 2700K Warm White none flicker LEDs, fitted by a professional, and doing your bit for the environment withought sacrificing style.

Win, win, win!

Come on Tytlas, enter the real world of the bog standard user. All they want is a decent light at the cost of pence………not £s, and cost effective, statistical analysis.

OK – buy a £14 LED 7W GU10 and it’ll save you £100 over it’s life, at least.

How’s that?

I smile. I have the intelligence and financial ability to understand you. You fail to grasp that you have to carry everyone with you. They yearn for the day when they (and me) could go and buy a pack of 3 pearl or plain for under £1 which would last them (and me) for years, whilst providing excellent, instant light. When the bankers and politicians have cost us (especially savers) billions £s does anyone really consider it worthwhile to save £100 ‘over its life’?
And what about the missiles they are throwing around like confetti in Syria…..Cruise ships, space rocket launches, growing world population, depleting resources. …..
Oh dear, much more important things to worry about if you wish to save the planet !

In my last post for ‘Syria’ read ‘Libya’

Gidster asked a question and I hope I answered it, but I am sorry if I failed to grasp that I was supposed to bring about world peace as well. Don’t worry, I’ll do better next time… 😉

I take your points on board tytalus so no intention to offend.
World peace would be wonderful but I was trying (unsuccessfully) to draw a comparison between the cost, use, and damage to the environment caused by light bulbs, and the cost and damage to the environment caused by the major political powers and businesses, with little or no comment. I feel that the ordinary citizen is being burdened with all the responsibility whilst governments and business continue with impunity and without comment. Rest assured, whilst I am not convinced about ‘energy saving’ bulbs, I have no car or television and enjoy wild camping and life in the mountains. A wonderful ‘carbon saving’ life.

Tytalus’ stat’s are good and don’t disagree with them, however I do disagree with eth life of LED lamps as stated by the manufacturers and web sites such as Which?.

I have had 2 GU10 LED lamps and they both failed partially (some of the leds still functioning) or tiotally within less than 250 hours of use.

I won’t buy any more.

LEDs suffer the same issue as everything else: they are not all created equal and you get what you pay for.

Our 2 Philips GU10s have been going for a couple of years now (1000+ hours?). They are the triple LED ones, and I’ve have bought more if it wasn’t for their narrow beam. 25deg is not standard, no matter what it says on their box; all the normal halogen bulbs i’ve seen are more like 36 degs. Going to show that even a big manufacturer stretches the truth at times… 😉

Both LED and quartz halogen bulbs last much longer if left running continuously. Repeated off/on cycling reduces their life due to “thermal shock”. I have two 2W LED bulbs in a kitchen display cabinet which provide sufficient light to make a cuppa by and are left to run continuously. They have been doing this for the last 5 years at least. I think we should be treated like adults and be allowed to choose our own bulbs according to use.

MacKay of Ardoch says:
11 July 2011

The one thing I really like about energy saving light bulbs is the fact that they start off dim and brighten up slowly. I think it’s really nice.

Agreed, one must not quibble about paying a lot more £s for products which are of such excellent design and quality.

IanP says:
12 July 2011

Dear Stan

I did not write stanjacos but Stan Jacos. 0k ?

You spelt harmful wrongly. It’s got just one l.

You spelt paraffin wrongly. It’s got one r and two fs.

I’ve got new glasses. See?

So there, clever dick!

Hello IanP, it’s fine to disagree on Which? Conversation, but please try and keep it civil (this goes out to Stan as well). If you’re unsure, just have a read of our Commenting Guidelines. Thanks!


Gidster says:
12 July 2011

World peace would be nice…but I did get the answer to my question… thanks!!

Unfortunately the savings probably dont justify the immediate outlay… especially as I imagine LEDs will continue to get cheaper…

Many thanks!

There’s always going to be issues with new stuff, especially for early adopters: up front high costs, unknown problems, flakey technology and the biggy, Change.

I feel that we are still at the early adoption stage with LEDs, so I fully understand and respect your view. However, my wife and I are techies in every sense of the word, including trying such things out, hence why so many of my posts as, if it’s hard for us, we really need Which to do more reports on CFLs and LEDs so that we can all make informed choices without losing money.

Even when you introduce change over time, as with CFLs that we’ve been getting for 10+ years, losing the option to use an alternative feels like an imposition too far. And, of course, there will always be doubters, as it was with the change from Gas to Electric light, horse to car, land-line to Mobile phone. I’m therefore heartened that you’re keeping an open mind and just biding your time! 🙂

IanP says:
13 July 2011

Sorry Patrick (and Stan) – no offence meant. Best regards for all for the well meant and helpful comments.

his047 says:
22 July 2011

It is not really a question of how quickly the light goes on that is important to me: instead I am concerned about the quality of the light. The easiest test is to take a look at your hands in the light given out by these low-energy lamps. To my eyes it is flat and lifeless and slightly blueish.

a more scientific approach would probably show that the light spectrum given out by low-energy light bulbs is spiky, i.e. has varying levels of energy in specific narrow light bands. Compared to a filament light-bulb which has a smooth decay of light from red to purple this seems not good to me.

Finally, My house is heated by electricity. Am I actually saving anything by using low-energy light bulbs? I have to compensate for the lack of heating by the filament lamps by turning up my electric heaters.

Aussie voice says:
20 August 2011

When the Australian govt started banning the much maligned tungstens, I hoarded them, My sad discovery has been that the bulbs I was able to buy have all been bad quality lasting only a month or two before blowing. But at least I had premium illumination while they lasted.

I do however have one amazing tungsten bulb which I have had in my lounge room since April 2000.Thats about 100,000 total hours so far. It is a RingGrip or “Philips IQ Range”. Mine is the Dimmable smartbulb which starts at 60watt pearl then dims up to 2 times when swiched off/on twice. Also available in the “Philips IQ Range” were a Sensor / Motion Activated smartbulb for indoor /outdoor which would come on for a few minutes then go out. Finally there was the Powersaver smartbulb which turned itself off after 10 minutes.

Shortly after I bought my bulb and found that it worked well, I returned to buy one of each type but they had been discontinued. Recently I searched to buy some on-line without success, but I have found websites devoted to these amazing obsolete tungsten lightbulbs! Why? Because:

At a cost per lightbulb of about US$2 or AU$4 in 2000:
They have generally lasted 10 – 15 years each!
They came with built-in energy saving features!
Each bulb had a feature which did away with the need to pay for such things as timers, remote controllers, and tranformers, special fittings, and installation, and dimmer switches or dials, special dimmable bulbs, and new wiring, and associated extra energy costs!
They reduced the owners energy use!
They used light bulbs which gave good light!

When the major lightbulb companies including Philips were desperately trying to compete with the (wholly China-made) CFL market by creating an acceptable,energy efficient tungsten bulb, they could have just reintroduced the IQ range. Wish they had…

Here’s a thought for you to consider when mulling over life spans and possible savings.

When John Rylands died in 1888 his wife, Enriqueta, built a library in his memory. It is the famous John Rylands Library on Deansgate in Manchester. Mrs. Rylands spared no expense and wanted her library to be illuminated by the newfangled electrical lighting.

The library was built between 1889 and 1900 and opened to the public in 1900.

Throughout it was illuminated by tungsten filament lamps just like the ones that are still in billions of homes and shops and offices now but are being phased out.

In 2003 the library was re-wired and it was discovered that a significant percentage of the bulbs in the fittings that were still working were original bulbs fitted in the 1890’s and in daily use ever since.

Some of these tungsten lamps were re-fitted after the rewire and continue to operate now.

Tungsten filament lamps in daily use for over a century and still working: you’d have to have some friggin’ amazing cfl’s to make any economically viable sense of replacing them and you’d also have to have some amazing recycling schemes for the CFL’s not to me thousands of times more polluting on disposal than several hundred over a century old tungsten lamps.

And finally, the tungsten lamps have not damaged the priceless manuscripts and texts in the library, but the UV light emitted from cfl’s would do so in hours. let along decades or a century.

I know this is not 100% relevant as most of us don’t have working 120+ year old bulbs in our homes, but the point I’m making is that saving a few watts of energy and a few pennies on the electricity by fitting cfl’s is all well and good (and welcomed) but it isn’t the be all and end all of the issue.

It’s not so much the time it takes for the lights to fail, though it does help. The main factor is the power used: my mum’s kitchen had almost 1kW of 50W GU10s, and she spent several hours in there a day. Being Manchester it was often overcast during the day, so the things were never off.

You can’t convince me that this is just a few Watts: it’s hundreds of pounds per year for mostly little gain; leave heating to the radiators and light to something more efficient. Oh, there is also the issue of the environment, but that’s another discussion…

Martin L says:
6 February 2012

This is a great article, that should be revised, or perhaps “updated” with current products and pricing. LED lights have come down quite a bit in price, and they will be coming down even more. As demand surges, prices will become more adequate, allowing us to switch to LED lighting sooner. Some are waiting to switch, others are switching slowly. In the end, we will all use LED lights, like the GU10 LED’s we’ve seen around for a while. Also, a lot of newer products are coming out, with better CRI, efficiency per Watt, and life/durability. In a few years, I’m sure we will be able to replace 50W GU10 halogens, with 4W GU10 LED ones, for as little as £3-4. Today, they cost about £6.49 from http://www.ledlumens.co.uk. Other sites have them for about a pound more or less.

Richard F says:
3 April 2012

How do I decide what size light to install. What do the markings on the light bulb mean?

Look for the brightness, which is quoted in lumens.

An old fashioned 60 watt bulb produces around 700 lumens and a 100 watt bulb produces around 1300 lumens.

Assuming that you are looking at compact fluorescent lamps, it is probably best to choose a bulb that is a little brighter than you need. The running costs are much less than for the old bulbs.

I’ve started using LED MR16 LED 6w lights in place of the 50w halogens that were used before. Very impressed. Bought on eBay from Hong Kong. In addition, a 13w 263 led corn Edison bulb that is now in place in the kitchen. Stunning light.

sad led says:
16 April 2012

I too have started using a number of LEDs in my house. I’m happy with the lighting appearance and low energy usage.
However, I’m very disappointed with the high levels of radio frequency interference (rfi).
My FM radio hisses when these lights are switched on. So it’s either listen to the radio in the dark or have the lights on in silence. Fine for ‘book at bedtime’ though.
I can’t see how these lamps can have a ‘VALID’ CE Mark and still give out high rfi.
I bought these lamps from a national electrical wholesaler and am waiting for their comments.
Perhaps a good subject for WHICH to investigate since I can’t afford to have the lamps tested myself. There does not seem to be any monitoring of the validity of the CE mark or more importantly the testing which should support it.
Bring back the ‘kite’ mark?

sad led – That’s very interesting, that it’s that bad. Is this only with LED type bulbs? Are they all from the same brand, or different brands? And are they of different ages or all bought at the same time. Sorry for so many questions!

sad led says:
30 April 2012

Richard – The LED lamps are all new, bought / supplied by the electrician in two or three batches. These appear to be the only souce of interfernce to the radio. They are same brand and of the GU10 (240V) type. One other piece of information, two of the lamps went bang (within the a few days) tripping the breaker. This can happen to any new electronic equipment I guess. We have a total of over 40 LED lamps througout the house, in the kitchen/ breakfast room, bathrooms, dining room, and a couple each in the bedrooms.
Our other lighting (wall lights) are the slightly less efficient PL flourescent lamps using the transformer type ballast as opposed to the electronic/hf type.
I try to avoid wireless devices where possible but I suspect that I am subject to more radio waves from the lamps than any potential wireles systems that pervade the home.
From my searches on the web on this subject the big loosers are likely to be the radio amatuers as the airwaves become clogged with rfi.

I do not know if Which? looks at rfi when testing LED and CFL lamps. If there is a significant difference between brands then it would obviously be useful to have this information. It’s not just the airwaves, but mains-borne interference that we have to cope with, and many modern products generate interference.

In the same way that astronomers have to live with light pollution, I believe the best solution is to use a roof or loft radio aerial and this should eliminate interference problems. Not many would think of using a TV from an internal aerial.

Some find Internet radio and wireless broadband a good solution for use with portables, but I guess you would not like to go down this route. 🙂

Thanks for the information sad led. In response, and to answer wavechange’s questions, RFI is not something we currently test for – but the experiences related in this Conversation and from other sources is making me realise it’s something we will at least need to warn people about.

sad led says:
30 April 2012

Wavechange – Thanks for your comments.
As part of the renovation project I have installed various data and av cables around the house. It’s the potential interference with these that concerns me most. The problem with the radio will be temporary since I hope soon to install a sat. dish & tv/dab aerial (in the garden to avoid masking of sat. & tv mast by trees.
Another issue which could be making the situation worse for internal aerials is Kingspan type insulation with foil backing in the roof.

I agree with your comment on mains-borne interference also being an issue. It is the RFI created by the lamps which is transmitted onto the lighting mains, which is then radiated from the lighting/mains cables into the airwaves. Some interference may also enter the mains network.

I believe that the future of lighting will be LED’s.
The problem I see right now is that cheap LED’s, without filtering of the power supplies, will flood the market because customers will naturally buy the cheaper product.
Without policing of the EU reg.s & international standards the consumers have no protection.

I agree on the importance of standards for LED lighting. Poor quality has been a problem with CFLs and we don’t need a repeat of this. Apart from RFI, standards should cover safety, longevity and efficiency.

Best of luck with the radio reception.

Smaci says:
18 May 2012

Just had 4 GU10 bulbs fitted to bathroom and as soon as we turn lights on both digital and FM radio signals fail! Digital goes mute and FM hisses furiously! Put in halogens and no problems! Only thing is halogens burn at much higher temps and bulbs are to be placed into plastic roof!

Frits says:
31 October 2012

Just a quick note on the CE mark.
Most products from China carry the CE mark. It’s not quite the same as the European CE mark. The distance between the two characters is different and the Chinese CE stands fror China Export.

stephen turner says:
22 August 2014

Do energy saving light bulbs emit the full spectrum of light, say for growing plants in an aquarium as the purpose bulbs are so expensive

LED lighting is increasingly used for aquaria. As with older fluorescent lighting, there is not a huge amount of competition, so prices are high. LED lighting should be safer because mains voltage can be kept well away from water. If it’s well designed it should work without significant loss of light output for many years. Look for long warranties because ordinary domestic LED lamps sometimes fail prematurely.

It’s well worth understanding the terms ‘colour temperature’ and ‘colour rendition index’, which manufacturers of aquarium lighting are likely to mention in their advertising.