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A guide to choosing energy saving light bulbs

13 November 2014 ( 26 February 2020 )

Your guide to energy-saving light bulbs, including which ones to choose, safety tips, frequently asked questions and how to save money.

Energy-saving lightbulbs
How to choose the right energy-saving light bulbs

Check the brightness of your energy-saving light bulbs

Although the brightness of energy-saving bulbs is measured in lumens not watts, there are also different wattages for energy-saving light bulbs that it's worth being aware of, so you choose the correct ones for your needs - especially if you are replacing traditional light bulbs.

If you want to replace a traditional light bulb with an energy-saver that offers the same level of illumination, you need to understand how brightness is measured in the new light bulbs.

Traditional light bulbs had a certain wattage – 40w, 60w or 100w, for example.

But the brightness in energy-saving light bulbs is measured in lumens.

Read our FAQs on energy-saving light bulbs

How to convert watts into lumens

To get the same brightness as an old-style 40w bulb, you’ll need a new bulb that offers more than 400 lumens.

A 6w light-emitting diodes (LED) light bulb would do the job, for example; this gives you an idea how much less energy these light bulbs consume.

Your new light bulb's packaging should tell you what wattage of traditional light bulb they are designed to replace.

If you are specifically looking for a replacement for an old-style incandescent 60w bulb, you’ll need an energy-saving bulb that emits more than 700 lumens to get the same level of brightness.

With a classic compact fluorescent lamp (CFL) light bulb, this means at least a 12w light bulb, a 42w-53w halogen light bulb or a 10w LED light bulb. And look for a light bulb which emits “warm white” light.

The glow from energy-saving bulbs can range from blue to warm yellow: check the packaging before you buy.

Read our safety tips for using energy-saving light bulbs

Which energy-saving light bulbs offer the biggest savings?

The more you use an energy-saving light bulb, the more you should save.

LEDs are the most expensive, but you will recoup the initial expense more quickly if they used frequently and for long periods, such as in a kitchen or living room.

It can be worth paying more for a light bulb which will light up more quickly or last longer.

What shape energy-saving light bulbs should you choose?

Take the bulb you’re replacing with you to the shop to make sure you get the right type of fitting.

Your fitting may have the correct code on it. This could be B22 or B15 for bayonets, or E4 and E27 for screw-ins. So make a note of this to ensure you get the correct match.

Find out more about energy-saving light bulbs

Will energy-saving light bulbs save you money?

The running costs of energy-saving lighting are lower than for traditional bulbs of the same brightness, but the bulbs themselves are more expensive.

Over time, you should recoup this extra expense in the form of lower electricity bills. But how quickly this happens depends on how often you use the light and how bright it is.

If you replace a single incandescent bulb with several energy-saving spotlights, on the other hand, your electricity bills could end up rising.

According to the Energy Saving Trust, replacing the traditional light bulbs in a typical home could cost £110 but save £45 on electricity a year.

A guide to energy-saving light bulbs

How long on average will an energy-saving light bulb last?

Energy-saving bulbs have much longer lifetimes than traditional incandescent bulbs.

LED lights are the most expensive of the new breed of lighting, but they can be expected to last for two decades or more, depending on how intensely they are used.

Halogen bulbs have a shorter lifespan of around two years – and bear in mind the energy savings offered by halogens are not huge.

CFLs can last for up to 10 years. Manufacturers print details of expected lifespans on the bulb packaging, usually in years or hours.

The recognised minimum lifespan for LED lights is 6,000 hours – used for two hours a day, this would cover more than eight years, although some producers claim their bulbs will last for as long as 25,000 hours.

Can you use energy saving light bulbs with dimmer switch light fittings?

As energy-saving light bulbs have become more popular, the technology has improved and manufacturers now offer a wider range of products.

It is now possible to buy light bulbs which work with dimmer switches: most CFL and halogen bulbs can be used in this way, but check on the packaging of LED bulbs that they are labelled “dimmable”.

Choosing the right energy-saving light bulbs

Do you need different energy-saving light bulbs for indoor and outdoor use?

To replace traditional light bulbs inside your home, you can use any type of energy-saving bulb – CFL, halogen or LED.

All you need to consider is the fitting, brightness, price and energy-efficiency of each option.

And to replace light bulbs outside your home, for example in security or patio lights, you should bear in mind that CFLs have been found to work poorly in colder conditions.

This could also be an issue when choosing lighting for your garage or other unheated outbuildings.

Some light bulbs are specially designed to be used outdoors and contain light sensors so they switch on automatically when it gets dark.

Where are the best places to buy energy-saving light bulbs?

With traditional incandescent bulbs no longer available in the shops, the range of energy-saving bulbs available has grown rapidly.

So how do you choose a bulb, and make sure you are getting something which is reliable?

Generally, LED bulbs will last longer than any other type. As previously stated, think of a minimum of 6,000 hours’ lifespan, although manufacturers often claim significantly longer lifetimes, sometimes of three or four times as long.

LEDs are more expensive but should prove more economical in the long-run.

Visit online retailers such as Amazon to see what brands other buyers recommend. And as a rule of thumb choose light bulbs with a large number of reviews that are overwhelmingly positive.

Energy-saving light bulbs safety tips

Has the technology of energy-saving light bulbs improved?

The good news is, the technology used in this type of lighting has moved on over the past few years. You no longer have to wait minutes for lights to turn fully on, or settle for a cold blue glow – two of the biggest early criticisms of energy-saving light bulbs.

They remain, nonetheless, more expensive than traditional incandescent lights: but you can expect to recoup this extra expense in longer lifetimes and lower running costs.

According to the Energy Saving Trust, replacing old-style light bulbs in a typical home can cost just over £100, but will lead to something in the region of a £45-a-year reduction in electricity bills.

How do you choose the right energy-saving light bulbs?

Make sure you select the correct fitting for your sockets. Energy-saving light bulbs fit in exactly the same sockets as their traditional counterparts.

They are available in bayonets and screw-ins, as well as the less common fittings that might be found in bathroom lights or spotlights.

Choosing the right energy-saving light bulbs

Your fitting may have the correct code on it – B22 or B15 for bayonets, or E4 and E27 for screw-ins, for example – so make a note of this or take your old bulb to the shop to get the correct match.

What types of energy-saving light bulbs can you buy?

The two main choices are CFLs and LEDs. Halogen light bulbs are also available, but these are not much more efficient than incandescents.

CFLs are cheaper than LEDs but cost a bit more to run. LEDs, however, can be expected to last for more than 20 years. Some cheaper CFLs may take a few moments to reach full brightness.

Energy-saving light bulbs: frequently asked questions

Warm white or cool white – the choice is yours

In the early days, energy-saving light bulbs were often criticised for the light they produced – some people felt it could be too cold, for example. But you can choose how warm or cold an energy-saving light bulb’s glow is.

Warmth is measured in the kelvin temperature scale. An LED light bulb at 2,700 kelvin would be the equivalent to a traditional incandescent bulb – this is sometimes called “warm white”. The higher the kelvin rating, the whiter or bluer the light.

How to handle a broken energy-saving light bulb safely

Some energy-saving light bulbs contain a small amount of mercury, a metal which can be hazardous to health.

Mercury is only found in CFLs, not in LEDs or halogen light bulbs.

If you break a CFL, you should take certain precautions. Firstly, make sure pets and other people leave the room. Open a window if possible. Use stiff card to clear up larger pieces and sticky tape for smaller bits of glass – avoid vacuuming as this can spread the mercury vapour.

How to dispose of energy-saving light bulbs safely

Normal light bulbs, plus LED and halogen bulbs, can be thrown away with general household waste, but the same is not always the case for energy-saving light bulbs.

Please note, however, that due to the metal content and the type of glass used in the manufacture of LED and halogen bulbs, these types of bulbs should not be included with glass recycling. The same is true for traditional incandescent bulbs.

With CFL bulbs containing small amounts of mercury, they have to be disposed of at a local authority recycling centre. A growing number of electrical and other retailers offer a recycling service which can also deal with this.

To find you nearest recycling site, visit the Recolight website at


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The opinions expressed are those of the author and are not held by Saga unless specifically stated. The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.

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