Energy Saving Light Bulbs: LED vs Halogen vs CFL, Lumens and Fittings

Updated October 2026 · Meteor Electrical guides · 10 min read

Most halogen and fluorescent bulbs have now been phased out in the UK, so most people replacing a bulb are choosing an LED. This guide compares LED, halogen and CFL bulbs, explains lumens and watts, and shows you how to pick the right fitting, colour and dimmable bulb, plus how to work out your own savings.

Which energy saving light bulbs are best: LED, halogen or CFL?

Three types of bulb have been sold as alternatives to the old incandescent bulb. LEDs are now clearly the most efficient, and they have replaced halogen and CFL bulbs for almost every use.

LED bulbs

An LED bulb makes light by passing current through a semiconductor, so very little energy is wasted as heat. LEDs light instantly, handle frequent switching well and come in every common shape, from GLS and candle bulbs to GU10 spotlights.

Halogen bulbs

Halogen bulbs are an improved filament bulb. They give a bright, crisp light but are only slightly more efficient than incandescent bulbs and run hot, which is why they have been phased out.

CFL bulbs

Compact fluorescent lamps (CFLs) use a gas-filled tube and a phosphor coating. They use much less energy than filament bulbs, but they can be slow to reach full brightness, are rarely dimmable and contain a small amount of mercury. Compact fluorescent lamps are still found in some commercial fittings.

Are halogen and fluorescent bulbs banned in the UK?

Yes, for most types. Under ecodesign rules, most halogen bulbs were phased out of sale in Great Britain from September 2021, and most fluorescent lamps, including many compact fluorescent and tube types, followed from 2023. Northern Ireland and the Republic of Ireland follow EU rules with broadly similar timelines.

• It is not illegal to keep using the halogen or fluorescent bulbs you already have.
• Shops were allowed to sell remaining stock, and a few specialist lamps were exempt.
• A new energy label was introduced in 2021 on a stricter A to G scale, so many good LED bulbs now show a lower letter than before. Compare lumens per watt instead.
• When a halogen bulb fails, the practical replacement is an LED with the same fitting and similar lumens.

Lumens vs watts: how bright a bulb do you need?

Watts measure the power a bulb uses, not how bright it is. Lumens measure the light it gives out. Because an LED gives far more lumens per watt, compare bulbs by lumens and use the wattage only to compare running costs.

These are typical values; check the lumen figure on the box, as it varies between products. For a fuller conversion chart, see our guide to LED equivalent wattages compared with traditional bulbs.

What colour temperature should you choose?

Colour temperature, measured in kelvin (K), describes whether light looks warm and yellow or cool and blue. It does not change how much energy the bulb uses.

Use the same colour temperature throughout a room so the light looks even. Our guide to choosing interior lighting for every room has more ideas.

Which bulb fitting do you need: GU10, E27, B22, E14 or MR16?

Check the cap on your old bulb, or the marking inside the light fitting, before you buy. The most common UK fittings are:

MR16 bulbs need a 12V supply. When you change MR16 halogens to LED, check that the existing transformer works with LED loads, or replace it with a suitable LED driver. Many people replace MR16 fittings with mains GU10 downlights instead; our guides to LED downlights and energy efficient ceiling spotlights explain the options.

Can energy saving bulbs be dimmed?

Many LED bulbs can be dimmed, but only those marked as dimmable on the pack. Non-dimmable LEDs on a dimmer can flicker, buzz and fail early.

• Use an LED-compatible dimmer, usually a trailing edge type.
• Check the dimmer’s minimum load. A few low-wattage LEDs may fall below it and flicker.
• Check its maximum LED load, which is far lower than its old halogen rating.
• Use the same make and model of bulb on one dimmer for even dimming.

Read more in our guides: can you use a dimmer switch on LED lights? and why do LED lights flicker with a dimmer?.

How much do energy saving bulbs save?

Your saving depends on the bulbs you replace, how long they are on and your electricity unit rate. Work it out in four steps:

1. Watts saved: subtract the LED wattage from the old bulb wattage. For example, a 60W bulb replaced by an 8W LED saves 52W.
2. kWh saved per year: watts saved ÷ 1,000 × hours per day × 365. At 3 hours a day, 52W saves about 57 kWh a year.
3. Money saved per year: kWh saved × the unit rate (pence per kWh) on your bill.
4. Payback time: bulb price ÷ yearly saving.

Bulbs in rooms you use most, such as kitchens and living rooms, pay back fastest. Replacing a ceiling of halogen GU10s with LEDs usually gives the biggest single saving, because there are several bulbs on one switch. LEDs also last much longer, so you buy fewer replacements.

The Energy Saving Trust has more advice on cutting home energy use.

Video: A guide to energy saving lighting. Credit: Energy Saving Trust.

How do you dispose of old bulbs?

• LED and CFL bulbs count as electrical waste. Do not put them in the household bin; take them to a recycling centre or a retailer take-back point.
• Fluorescent tubes and CFLs contain a small amount of mercury, so recycle them carefully and do not break them.
• Incandescent and halogen bulbs are not usually recycled as electrical waste. Check your local council’s guidance.

Recommended energy saving bulbs

All of these are LED bulbs from our LED lamps range. Check the lumens and colour temperature on each product page before ordering.

Kosnic 9.5W B22 LED GLS lamp

A warm white, standard shape bayonet bulb for ceiling pendants and table lamps, as a direct replacement for an old filament GLS bulb. Shop the Kosnic B22 LED GLS lamp.

Kosnic 4W GU10 LED lamps

Mains GU10 spotlight bulbs to replace halogen GU10s in downlights and spotlight bars, in warm white 2700K and cool white 4000K.

Kosnic 5.5W GU10 dimmable LED lamp

A warm white GU10 for spotlights on a dimmer circuit, used with an LED-compatible dimmer. Shop the dimmable GU10 LED.

B22 LED candle bulbs

Small candle bulbs for chandeliers, wall lights and decorative fittings, in a 4W clear filament version for a traditional look or a 5W frosted version for a softer light.

Choosing energy saving light bulbs

For almost every light in a UK or Irish home, the best energy saving light bulb is an LED. Match the fitting on your old bulb, choose the lumens you need rather than the watts, and pick a colour temperature that suits the room. Use dimmable LEDs where you have a dimmer, and recycle old CFLs and LEDs properly.

Need help choosing? Call our team on 028 8675 1515 (048 from ROI), Monday to Friday, 8am–5pm.

FAQs

What are the best energy saving light bulbs?

LED bulbs are the best energy saving light bulbs for UK homes. They use far less electricity than halogen or old incandescent bulbs for the same brightness, last many times longer, light instantly and contain no mercury. Choose one with the right fitting, lumens and colour temperature for the room.

How many lumens is a 60W bulb?

A traditional 60W incandescent bulb gives about 800 lumens. To replace it, look for an LED bulb of around 800 lumens, which is typically about 7 to 9 watts. A 40W bulb is about 470 lumens and a 100W bulb is about 1,500 lumens.

Can you still buy halogen bulbs in the UK?

Most halogen bulbs were phased out of sale in the UK from September 2021, and most fluorescent lamps followed from 2023. Shops could sell remaining stock, and a few specialist types were exempt. You can keep using any halogen bulbs you already have, but LED replacements are widely available.

What colour temperature should I choose?

Choose warm white, around 2700K to 3000K, for living rooms and bedrooms, as it gives a cosy light similar to old bulbs. Cool white, around 4000K, suits kitchens, bathrooms and workspaces. Daylight bulbs of 5000K to 6500K are best for tasks that need bright, crisp light.

Are LED bulbs dimmable?

Only LED bulbs marked as dimmable can be used with a dimmer. You also need an LED-compatible dimmer, usually trailing edge, whose minimum and maximum loads suit the bulbs. Using non-dimmable bulbs or an old dimmer can cause flicker, buzzing and shorter bulb life.

How do I work out the savings from LED bulbs?

Take the watts saved per bulb, divide by 1,000 and multiply by the hours used each year to get the kWh saved. Multiply that by the unit rate on your electricity bill to get the yearly saving. Divide the bulb price by the saving to find the payback time.

Related guides

• LED equivalent wattages compared with traditional bulbs
• Can you use a dimmer switch on LED lights?
• LED downlights UK guide
• Energy efficient ceiling spotlights