/ Home & Energy

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.


Which reports tell us there is no problem with warm up times these days – but if you use an ESL which looks like a “normal” bulb they take ages to warm up especially once they are more than a few months old and who wants spirals and tube types in their carefully chosen light fittings ?

The issue with dimmers, time switches and security lights still exists so what do I use in my bulkhdae security lamp outside to replace the 60w tungsten lamp which comes on for all of 2 mins at a time ?

Hi Kelly

I think you mis-read my post, or I was being too obtuse!
I said there WERE still problems with warm-up times .!
But if you read the WHICH magazine reports you get the impression that this is NOT a big issue anymore.

Hi rarrar, as Kelly writes in the article it depends on how good the bulb is. And as she explains our lab tests (which our reports are based on) found that the problem still exists with CFLs:

“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.”

I agree with your comments but if you read the latest WHICH? report you do not get given the impression that startup times are a major problem.
“Some Compact Fluorescent Lamps (CFLs) take a few seconds to achieve 60% light output. ” is the only comment in the report.
However if you delve into the test results none of the best buy CFLs got more than 3*, and bulb shaped CFLs got a max of 2*; so obviously there is a problem which this Conversation highlights.
Why a Which Conversation saying there is a big problem with start up times and a Which? Product report which hardly mentions a generic problem ?

I have not tried any CFL lamps bought within the last 8 months, but all others that I have tried have been very unsatisfactory – warm up time, short life, interference with radio and TV and cordless ‘phones, light quality, etc., etc. – all the issues raised by thousands of others too.

I have to say, though, that the old “Jam Jar” ones that Phillips used to make back in the 1980’s were fantastic. I had one on the landing that lasted over 12 years and it was on all through the night every night of it’s life.

It was, however expensive and ugly. The ugly part did not matter on the landing as it was inside a white glass globe and could not be seen. I strongly suspect, though, that in order to make the compulsory change to CFL’s sufficiently palatable to the public to prevent a widespread revolt (and the loss of politicians’ jobs), manufacturers were ordered to find ways to make the lamps cheaper, and that probably accounts for the majority of the problems that we are now plagued with and which are clearly not yet fixed.

My view is that we had the technology to do the job right, but the cost was unattractive, so we “broke” the technology to lower the price.

Anyone else had a similar experience with the expensive “jam jars”?

Dave: I have still got a two of the expensive ‘jam jar’ lamps made by Philips in the 1980s. These lamps are very heavy (over 630g for a 25 watt lamp) because they contain a conventional steel choke ballast, unlike modern CFLs which contain a small circuit board. After start-up, when they may flicker for a second or more under cold conditions, they will produce less radio interference than current CFLs.

The warm up time of these old lamps is better than some of the CFLs that have followed. The efficiency is lower than electronic CFLs and newer lamps tend to provide better colour rendering due to improved phosphors. Still the old ‘jam jars’ were a great step forward, providing the first step towards replacement of the incandescent lamp with something more efficient.

I suppose I should find a use for these lamps, which probably cost £10 each.

I rather like having a CFL in the bedroom. A light that reaches full brightness over a minute or so is less of a shock to the system in the middle of the night.

I feel so strongly about this over-hyped, expensive, wasteful, inefficient product, from manufacture, its use, to its disposal that I am best not expressing my honest opinion.

You shouldn’t really hold back, ggdad.

Sophie Gilbert says:
5 July 2011

“The moment when, after many years
of hard work and a long voyage
you stand in the centre of your room,
house, half-acre, square mile, island, country,
knowing at last how you got there,
and say,” just how long is this bulb taking to come on?!?

Honestly, folks, does it matter?

(Apologies to Margaret Atwood for using her beautiful poem, The Moment, in such a way.)

Well, I think it does, because if you replace something that does the job well, with something that doesn’t, then it’s a retrograde step.

What’s the point in energy saving lightbulbs if the energy companies keep putting up their prices? It completes negates the saving. And if the new bulb doesn’t perform as well as the old ones, then can someone please remind me why we are doing this?

john cross says:
5 July 2011

l used free cfl bulbs,for 2 years. l had to get under the bulb,to read paper,dim light. l had tension over my eye’s and suffered migraine attacks. l found out these bulbs are toxic,they contain mercury.which can cause,tension,migraine,fits, ect. if dropped they contaminate the area. since the removal of cfl bulb’s,l have no more tension,and migraine attacks?

CFL’s have the same amount of mercury in that roof florescents have had for the last 50 years – only much less.

If you use a quality bulb, the flicker rate is beyond the human comprehension and should not cause migraine. Buy a better product. Try Phillips, the fastest start up and they don’t flicker.

As for chemicals – this is a sealed unit – they can’t touch you as the unit is…sealed!
As for spillage upon breakage, one unit will not harm you, the quantities are too small and you’re more likely to get cut by the glass – only less so than regular bulbs which have thinner glass and more of it.

As for reading migraines – have you had an eye test – the most common cause is the lack of the correct reading glasses, ie eye strain.

CFL’s have the same amount of mercury in that roof florescents have had for the last 50 years – only much less.

I’ll agree to disagree.

Don’t buy cheap CFL bulbs from just anywhere – they are slow and dull in colour output.

Buy a quality bulb with a fast electronic starter – like the Phillips range and they are virtually instant.

I’ve been using them since 1990 (cost £15 a tube then, 2 still work)
Now they cost £1 in Morrisons.

This would make a brilliant article for Which!
– get on with it you chaps.

john cross says:
6 July 2011

uk goverment, state cfl bulbs are safe? the health protection agency, advise if you drop a cfl bulb,evacuate the room,open all windows and dont return for 15 minutes. put on protective gloves, pick up glass,then seal cloth and glass in plastic bag,do not place in bin? take the hazardous material to a recycling centre. if a cfl bulb use’s less energy,than our safe and bright incandescent bulb,it does not make it environmentally freindly.

I’d think twice about cheap supermarket bulbs. We’ve had two explode when turning on, showering glass down into the room.

Fred says:
8 July 2011

cfl bulbs are a truly awful product. Even the best ones are very dim in cold rooms, take a long time to warm up and make everyone look like extras from a zombie movie. They don’t fit into many older fittings and they should never have been introduced. LEDs are the best solution and there’s no reason for them to cost as much as they do if the volumes were high enough. The real problem with LEDs is that they last so long that the manufacturer may only ever sell you one set which doesn’t do the long term business model much good.

We’ve just installed 3 LED floodlights on the outside of my apartment block on IOM. I bought them on eBay for £30 for each of the 20w ones and £60 for the 30w one…. All came direct from China.

Buying direct in this way makes them less expensive, and apart from lower operating costs… I hope no replacement cost.

Paul says:
8 July 2011

I purchased a LED “corn bulb” from china to replace a CFL in a coach lamp outside the house on from dusk till dawn (we have no street lighting) thus going from 9w to 3w.
It lasted a little over a month before LED’s started dying, and about another two weeks before it died altogether! Now back to a 7w CFL
So I hope your experience is better than mine!

Sharon says:
8 July 2011

Ahh – but there’s a hidden problem with LED bulbs (especially the low voltage AC/DC LED type used in track lighting and flourescent tube replacement).
They interfere with ALL radio (AM, FM, DAB etc) and are, not to put too fine a point on it, being traded in Europe illegally! Many of them do not comply with the European EMC Directive.
And for this we’re paying ££s

Rosemary Nimmo says:
8 July 2011

We’ve just started using halogen bulbs. They use more power and aren’t so long lasting but are very bright and come on instantly. Not too expensive. They are a bit small for, for instance, clip on lamp shades, but, with power equivalent to 100W, they are ideal in hallways etc. Am hoping they will do a 150W replacement at sometime.

Having a lot to do with older people I’m particularly concerned that houses will be adequately lighted for safety – and how are people without trasnport supposed to dispose of used bulbs?

Stephen says:
8 July 2011

I have tried a number of different “energy saving bulbs” in our hall, both CFL and LED, and all of them have suffered the same problem – the colour of the light that they emit. It is far bluer than that produced by “normal” incandescent bulbs and makes our hall look like an operating theatre. Until they get the colour balance right I will still be looking for old fashioned bulbs that give our house a warm, friendly feeling at night.
The other problem we have is that our house has been fitted throughout with spotlights which are recessed into the ceiling. Our house has 83 of them, mostly controlled by dimmer switches. There is currently no satisfactory energy saving replacement I can buy as a dimmable substitute. This is aside from the cost consideration. When you multiply £15 per bulb 83 times you get a total cost in excess of £1,200 for taking a retrograde step. This is before even thinking about replacing the ceiling fittings or upgrading the dimmer switches.

Disappointed says:
8 July 2011

How come no-one has noted the following recent German report which advises that Energy saving light bulbs ‘contain cancer causing chemicals’ and the bulbs should not be left on for extended periods, particularly near someone’s head, as they emit poisonous materials when switched on.

Peter Braun, who carried out the tests at the Berlin’s Alab Laboratory, said: “For such carcinogenic substances it is important they are kept as far away as possible from the human environment.”

The bulbs are already widely used in the UK following EU direction to phase out traditional incandescent lighting by the end of this year.

But the German scientists claimed that several carcinogenic chemicals and toxins were released when the environmentally-friendly compact fluorescent lamps (CFLs) were switched on, including phenol, naphthalene and styrene.

Andreas Kirchner, of the Federation of German Engineers, said: “Electrical smog develops around these lamps.

“I, therefore, use them only very economically. They should not be used in unventilated areas and definitely not in the proximity of the head.”


It never ceases to amaze me how people believe all the ridiculous tripe published in the media.
Lets get one thing straight, the chemicals used to produce CFLs are no different to those used for many years to produce the “Normal” flourescent tube. How long have they been around! and how many are fitted throughout the world, hundreds of millions no doubt. The only difference being they use smaller quantities in CFLs. Does anybody with a modicum of intelligence believe that if these products were that toxic that their production and use would be condoned by the EU. Scientists have indeed published a report of their findings, it has been seized upon by all and sundry and magnified beyond belief, yes they do contain minute quantities of hazardous chemicals but no more than any normal flourescent tube, television, Sky Box and any other manufactured electronic component device. If you want to believe all the hype you read, play safe, get rid of every electrical device in your house and buy a lot of candles!!

David Hales says:
8 July 2011

Another advantage of halogen bulbs, or at least of those made by Philips, which we use in one room, is that they can be faded up and down, so rooms with only dimmer switches can use them.

Alan says:
8 July 2011

Have you ever tried listening to a medium wave or long wave radio channel, particularly when the signal strength is marginal. The interference from the lamp will render the signal unuseable.
Ruins ‘ Test match special ‘ !

Mervyn says:
8 July 2011

When discussing energy “savings”, Newton’s law of something says that energy is neither created or distroyed. In an “old” light bulb the extra energy was released as heat. Replacing this with a low wattage “energy efficient” bulb just means that the central heating system thermostat kicks in earlier and burns the equivalent amount of oil/gas/electricity that I was supposed to be saving – at least during the winter.

I think you mean the first law of thermodynamics.

If your lights are on the ceiling, most of the heat will stay there and electricity is generally the most expensive way of providing heat.

Robert C says:
8 July 2011

I’m all for saving energy – much of it is a finite resource – but governments (across Europe) should have done more to make recycling of the new types of bulbs easy, before phasing out the old incandescent bulbs. The new energy efficient bulbs contain so many materials, including mercury, that they deserve proper treatment. My local council suggest I drive a round trip of 20 miles to recycle mine – which hardly achieves the aim of the exercise.

Agreed: I’ve said before in a number of places that CFL’s are one of a lengthening line of products that have been foist upon us before adequate research or adequate facilities were put into place and now we are having to try to make a silk purse out of a sow’s ear with them.

The other issue I’ve raised several times and which no one appears to know the answer to is this: if CFL’s are so good why is it that INcandescent bulbs are to remain available for commercial users (shops, pubs, clubs, offices etc) on the grounds of “commercial need”?

As far as I can see the only possible reason for that discriminatory position is that the commercial users (who generally make the rules because of the wealth they have) will not tolerate being forced to change fittings and work with poor light, etc, and unlike us the public make the governments and manufacturers feel threatened so they get their way.

Margaret says:
8 July 2011

Apart from warm up time they are unsightly. Could appearance not be improved