Buying guide to light bulbs

Different styles and types of light bulb offer different lighting moods, strengths and energy efficiencies, so it's important to choose the correct one. Our guide will help you decide which light bulb is right, whatever you need it for.

Bulb types

Although there are many different shapes, light bulbs and lamps come in four main types:

Sometimes known as incandescent lights, these are the ordinary, everyday light bulbs that come with screw or bayonet caps. They contain argon gas and a very fine tungsten filament that's more than 6ft long (in an ordinary 60W bulb) and breaks easily if the bulb is shaken or dropped.

Electricity passes through the filament, which glows and heats up to reach a temperature of over 2000^oC (one good reason never to touch a lit light bulb!). Tungsten bulbs come in many different sizes, shapes, wattages, colours and finishes.

Here's the sunshine bulb! Halogen bulbs produce a very attractive bright light that closely resembles sunlight. You can buy them in lots of different sizes, shapes, wattages and colours.

Halogen bulbs have a tungsten filament and are filled with a mixture of argon and halogen gas. The bulbs are made from a more expensive, higher-grade glass that can tolerate the extra-high temperatures they reach.

They may cost more but halogen light bulbs can last up to three times longer than a standard light bulb of the same wattage, and can be 20% more efficient. There are two versions - mains voltage (240 volt) and low voltage (12 volt). These need a transformer but are 35% more efficient.

Before you choose, always check the style of pin your bulb has, as halogen bulbs come with a variety of pins and fittings.

These slim glass tubes have an electrode at either end and are filled with mercury vapour. When the light is switched on, particles inside the tube glow or fluoresce to give off bright white light that's ideal for kitchens. Fluorescent bulbs are four to six times more efficient than a normal light bulb because they heat up less when lit. Fluorescent tubes come in many different sizes, specialist shapes, wattages and in cool or warm light versions.

A unique design makes these bulbs less expensive and more energy-efficient. Electricity passes through the gas-filled glass bulb and makes the coating inside glow brightly. Because energy is used to generate light rather than heat, these bulbs can be up to 80% cheaper to run. (Though some complain they don't light up instantly and that the light is sometimes dimmer.)

They're more expensive, but these bulbs do save you cash in the long run, especially in areas where lights are left on for long periods. Below-zero temperatures can affect the bulb's performance so don't use in colder parts of your home.

There's just a tiny amount of mercury in a low-energy bulb (it could fit on the tip of a ballpoint pen), but mercury's hazardous nature means these types of bulb must be recycled rather than thrown in the bin.

Bulbs with higher wattage produce more light but consume more power. The watt is not a measure of brightness because different bulbs are more or less efficient in converting electrical power into light.

Doesn't turning lights on and off use more energy than leaving them running?

In normal household use, switching a low-energy bulb on and off shouldn't shorten its life. But leaving it on for a stabilising period of 10 to 15 minutes will help it last as long as possible. Traditional light bulbs should be switched off every time you leave a room unoccupied - in the UK£140 million a year is wasted by leaving lights on unnecessarily!

Why do some energy-saving bulbs take longer to light up?

Because the bulb lights up when the gas inside starts to 'glow', it can take a few seconds to reach full brightness. In a traditional bulb the filament heats up as soon as the bulb is switched on and so lights up immediately.

Do traditional bulbs give a better quality of light?

For technical reasons, the glass used in household energy-saving light bulbs has to be opaque, but many traditional bulbs are transparent. So it's not helpful to compare the light emitted from an opaque bulb with that coming from a clear bulb. When like for like are compared, you won't see a difference in brightness.

Are traditional tungsten bulbs being banned?

There's a government proposal for a voluntary phasing-out of traditional light bulbs between now and 2011 to give retailers time to develop replacement products.

Lights take various sizes and types of bulb. Typical fittings include: Bayonet Cap (BC), Small Bayonet Cap (SBC), Edison Screw (ES or E27) and Small Edison Screw (SES or E14).

We stock the right bulb for every light we sell and the bulb type you need is clearly written on the packaging of all lighting products. Before you buy, check the packaging first as many light fittings now come with bulbs.