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About low-energy light bulbs: introduction

Warm LEDLED bulbs are rapidly gaining acceptance as the ultra-low-energy option for many applications, in both the home and commercial settings.

Low-energy light bulbs, otherwise known as 'energy-saving lightbulbs', now come in a huge variety of shapes and sizes. The phaseout of the old incandescent bulbs (otherwise called 'tungsten filament' bulbs or 'general lighting service' (GLS) bulbs) was completed in 2012, but low-energy equivalents were available long before then.

The first generation of replacements were called compact fluorescent lights (CFLs), but they were often dimmer, slower to warm up, and uglier than the old-style bulbs. Instead, many people turned to halogen bulbs, which give a bright light but don't save much energy. The least efficient halogen bulbs were phased out by September 2016, with others to follow by 2018.

LEDs - the smart choice

Later designs of CFLs were much improved, both in looks and performance, and can still provide stylish energy-efficient lighting at relatively low cost. 'Energy-saving' halogen bulbs are only 30% or so more efficient than their standard versions. But in recent years there has been a dramatic increase in the styles and performance of LED (light-emitting diode) bulbs. These typically use a third less power than CFLs and have replaced them in many domestic and commercial situations as the smart choice for energy-efficient lighting. The latest designs resemble the old incandescent bulbs, with LED filaments inside a clear glass bulb.


The lighting industry makes bulbs and fittings for almost every conceivable situation - spotlights, downlighters, uplighters, wall lights, strip lights - to name just a few.CFL compact spiralCFL candle You can choose from a vast array of designs, giving light of different tone and intensity. As well as spirals and the traditional sticks, you can get traditionally shaped bulbs, or round and candle shaped, with bayonet or small or medium screw fittings. There are also replacements for halogen bulbs, reflector bulbs and even dimmable ones, as well as “soft tone” bulbs, which give a warm glow rather than a cold light. Price, performance and running costs are also significant factors in deciding which bulb to choose, or which type of fitting to install in the first place, particularly where a light is in regular use.

Many designs of CFLs are available, including the candle (above left) and compact spiral (above right)

Power consumption (wattage) and brightness (lumens)

Two main questions when buying a replacement bulb will be 'how much power does it use?' and 'how brightly will it shine?' Energy-saving bulbs are available to fill the place of all old-style incandescent bulbs, but use up to 80-90% less electricity. For example an esoft tone bulbnergy-saving CFL bulb only uses 20 watts of power to create the same light as an old 100 watt incandescent bulb. Brightness is measured in lumens; an old 60 watt bulb, say,would produce about 650 lumens. Hence, your low-energy equivalent should have at least a similar brightness to give a similar amount of light (see table below). Bear in mind though, that many new bulbs, particularly LEDs, emit light in a fairly directional manner - i.e. 'downwards' or 'upwards' (depending on their orientation), so light isn't wasted illuminating the light fitting!

Wattage conversion and brightnessmini globe bulb

Traditional bulb

Brightness (lumens) 'Low energy' halogen bulb Low-energy CFL bulb

LED equivalent*

100 W

1200–1300 80 W 20–25 W

18 W

60 W

650–800+ 45 W 13–18 W

9–11 W

40 W

350–400+ 28 W 8–11 W

5–7 W

25 W

200–225 18 W 6 W

4 W

*Note that LEDs do not necessarily match the output in lumens of their CFL equivalents, but directionality is better so giving an equally good light where required.

Cost and savings

The cost of energy saving bulbs is constantly falling. The average price of standard CFL bulbs is now less than £1, while the more specialist ones are somewhat dearer. The basic low-output LED bulbs typically now match the cost of CFLs, but prices rise according to quality, output, and style. Depending on how long your lights are on every day, just one energy saving CFL bulb could save you over £3 a year on your electricity bills, so even the more expensive ones can pay for themselves in 2–3 years. Because an energy-saving bulb will last up to 10 times longer than a traditional bulb, it could save you around £50-60 before it needs replacing. If you fit all the lights in your house with energy saving ones, you could save around £600 over the lifetime of the bulbs. This takes into account the higher cost of low energy bulbs.

The output of some low-energy bulb has been found to fall over time - they get dimmer as they get older. So make sure your CFL or LED bulbs carry an extended warranty, if possible for at least 5 years.

How to choose replacement bulbs

Buy energy saving bulbs for your most frequently used light sockets first, and fit in places where access is difficult or dangerous such as above stair wells – because they last longer, you won’t have to change them so frequently. Stick type CFLs, although less attractive, are very cheap, and can prove ideal for some locations.

If the lights are used outdoors, they should be enclosed in a sealed unit to provide thermal and environmental protection, as their effectiveness may be affected by cold conditions. The performance of CFLs is reduced by low temperatures, so opt for LEDs instead.

A useful interactive guide to choosing bulbs can be found on the Sust-it website. Similarly, bulbs are listed according to their energy rating on the topten website.

Phaseout of inefficient bulbs

A mandatory EU-wide phaseout of traditional incandescent ('tungsten filament' or GLS) lightbulbs started in 2009, with the banning of 150W and 100W bulbs, and ended on 1 September 2012, when shops were banned from selling all types of the old bulbs. Like it or not, everyone now has to use low-energy bulbs - and take comfort from their reduced electricity usage and consequent lower associated carbon emissions.

A similar fate is underway for halogen bulbs. September 2016 marked the end for sales of directional halogen spotlights and downlights, and halogen GLS bulbs will follow suit on 1 September 2018. Only specialist halogen bulbs used in spotlights and floodlights will remain on sale after then.

What’s wrong with traditional bulbs?

With traditional, or incandescent bulbs, light is generated when an electrical current is passed through a thin metal wire, and the wire becomes hot and emits light. Only 5 per cent of the electrical energy is converted to light, so 95 per cent of the energy that goes into them is wasted as heat. In contrast, the operating systems of energy efficient bulbs use electricity to produce light, not heat. They use the same technology as a fluorescent tube in strip lighting – they are coated with a thin layer of phosphorous powder which absorbs ultraviolet radiation and glows brightly when electricity is passed through gas in the tube.

Electricity consumption

At the moment, lighting accounts for around 15 per cent of domestic electricity consumption, with the average house having some 34 light bulbs. In 2013 the total energy consumption of domestic lighting was equivalent to over 1 million tonnes of oil, so the scope for savings in terms of energy cost and carbon emissions is immense. Lighting remains the third biggest consumer of domestic electricity, in spite of a 24% fall in consumption by lighting since 2000.

Choosing the 'Right Light'

Recent advances in lighting technology and the proliferation of low-energy products present a vast range of options to anyone thinking of revamping their living space or starting from scratch. The Energy Saving Trust has compiled a useful downloadable guide to selecting low-energy lighting aimed primarily at architects, designers and housebuilders. Called 'The right light', it covers all aspects from compliance and safety to performance and cost of the various types of bulbs and fittings.