Lighting is one of the easiest and quickest ways to use less energy in your home. You can change a light bulb at any time - it makes no sense financially or environmentally to wait for tungsten bulbs to fail, change them for energy saving bulbs NOW. 

  • Wattage and voltage

There is a common misconception that “low voltage” means low energy - this is NOT the case! Wattage (Watts or W) is what matters. Many halogen lighting systems are on a low voltage (12V) circuit with a transformer. These are particularly common in kitchens and bathrooms, where usually one central light is replaced with multiple halogens, increasing the wattage of installed lighting dramatically. 

  • Best practice in lighting

Use the lowest practical wattage of bulb in all fittings

Lighting should be easily controlled, whether automatically (sensors) or using switches/dimmers

Lighting design should prioritise natural light and be tailored to your use of space

  •  LED light bulbs

 LED technology has made great leaps forward recently, with high-quality replacement bulbs now available for practically all fittings in the home.

LED bulbs have a much longer life, typically 25-50,000 hours (roughly 25-50 years) compared to 2,000 hours (2 years) for a halogen bulb and up to 8,000 hours for a compact fluorescent bulb (CFL). They consume a tiny amount of energy: a 50W halogen can be replaced with a 7W LED with the same light output, reducing carbon emissions and running costs by 85%.

Further advantages include instant light at full output, with none of the slow warm-up of some compact fluorescent bulbs; they also give off much less heat than incandescent bulbs, reducing overheating during the hot summer months.

LED bulbs are available to replace both mains voltage (240V, including GU10 bulbs) and low voltage (12V or MR16) halogens. Although LED bulbs cost more to buy, their low energy use and long lifetime make them more cost-effective than halogen bulbs in most circumstances. They even outperform compact fluorescent (CFL) replacements for halogen bulbs on running cost and energy efficiency.

It is worth noting that LEDs still get very hot - although they generate less heat than incandescent bulbs they have to conduct it to the air rather than radiate it away.  As a result they should not be placed into small enclosed fittings as they are likely to overheat and possibly fail.  You should also let them cool down before removing them.

If you use a dimmer switch, make sure that any LED bulbs you are intending to use are compatible with it. Traditional-shape LED bulbs - GLS, candles, golf-balls and globes

A couple of decades ago most household bulbs were of the traditional round GLS shape - in the last few years LED replacements have become available in 40W, 60W and more recently 100W-equivalent outputs.  Generally these are only available in “warm white” to match their predecessors.

For greater savings replace pendant bulbs with lower-output LED bulbs which project most light down.

  • Mains voltage LED spot bulbs (GU10)

GU10 bulbs can be identified by the mushroom shaped projections of the fitting (upper right). MR16 bulbs have two pins instead (middle right).

As there is no separate transformer, you can usually directly replace halogen GU10 bulbs with LED versions.  Be aware that a minority of older and more powerful LED bulbs are longer than halogen bulbs (which are 57mm) and may not fit flush in recessed fittings.  GU10 and, in particular, MR16 bulbs are available in spotlight and various wide angle formats - spots work better if you can angle your lights towards worktops, whereas recessed lighting often works best with a wider beam.

Typically GU10 halogens have a 36 degree beam angle, so you may simply wish to replace like-for-like.

  • Low voltage LED bulbs (MR16)

When changing low-voltage bulbs it is recommended that you change all the bulbs attached to the transformer at the same time. Using a mixture of LED and halogen bulbs is not recommended - one or the other may not work, and LEDs can be damaged by the power spike caused when a halogen bulb blows.

It may also be necessary to change the transformer to a low power one as the LED power requirement is very low and transformers are rated to supply a specific wattage range. For example, if you change six 50 watt halogen bulbs for six 4.5 watt LED bulbs the power requirement is reduced from 300 watts to just 27 watts.

Be aware that 50W halogen MR16 bulbs are much brighter compared to 50W GU10 bulbs —if you are replacing these you will need to select an LED of at least 450 lumens to provide a similar degree of output.

The graph above illustrates the cost-effectiveness of different types of GU10 bulbs over time. 

The table below indicates the equivalent wattages of incandescent, CFL and LED bulbs of different types.  Light output is measured in lumens, and you should use this figure as a guideline when replacing bulbs.

  • Compact fluorescent light bulbs

Fluorescent tubes were the original low energy light. They are not as good as LEDs but are much more efficient than old light bulbs.

Compact fluorescent lamps or CFLs are available in a variety of styles and fittings (right).   Enclosed CFLs take longer to ‘warm up’ than spiral or stick bulbs - something to bear in mind if you need light to come on quickly, for example in a bathroom or above stairs.

  • Using CFLs with timers and dimmers

There is usually no problem with using ordinary CFLs in exterior lighting, however some PIR-switched lighting may cause CFL bulbs to fail quickly due to a low residual current even when the lamp is “off”.

Until recently you had to buy a special dimmer switch to use with CFLs but now there are special dimmable CFLs that work with standard dimmer switches.

  • The colour of light

Modern lights are made in various “colour temperatures” - a term which describes how “warm” or “cool” the light appears.

The colour temperature is shown on the packaging.  Colour temperature is measured in Kelvin (K) and this is often qualified by a description such as “warm white” or “cool white”.

The lower the Kelvin number, the “warmer” the light. If you are looking for a direct replacement for a tungsten bulb, you need a “warm white” - this is usually 2700-2800K.  Neutral or pure white (4000K) blends well with daylight, whereas “cool” or “daylight” white (6000K) can appear starkly bluish.

  • The law

You can of course change any light bulb yourself. If you want a new lighting system, the Building Regulations state that this needs to be carried out by a person registered with the Electrical Contractors Association ( or 020 7313 4800).

The Building Regulations for new homes specify that a certain number of bayonet light fittings must be of the type that can only take energy efficient light bulbs, however this will also limit the options for LED bulbs that you can fit.   These fittings (BC3 bayonet fittings) can be changed back to standard fittings by a qualified electrician.

  • Making the most of natural light

Have a look at the natural daylight potential before planning your lighting redesign:

Make sure your windows are clean inside and out, and that curtains clear them completely when open.

Reduce overshadowing from outdoors by pruning trees, and indoors by moving tall furniture away from windows where it funnels light into the centre of the room, leaving corners dark.

Consider the impact of choosing lighter coloured walls, ceilings and window frames, all of which reflect more light into and around rooms. A mirror in the right place can also help.

Are you making best use of south facing rooms? Or do you spend more time in rooms with less natural light?

Are interior doors helping or hindering the passage of light through your home?

Make sure the new lighting design enables electric light to complement, rather than replace, natural light. For example, have separate switches for lights near windows. Good aesthetic effects can be obtained by mixing daylight with electric light and light with shade within the same space.

  • Efficient lighting layout

Lighting has many functions: safety, security, decoration, creating the right mood and facilitating practical tasks. The layout should be designed around your needs. In the past, lighting has been more general purpose with a single, central light fitting mounted on the ceiling expected to provide sufficient light for a range of activities. If you have ever cut your hands while chopping vegetables with a single, central light directly behind your head, you will know this is often not adequate!

When designing new lighting, ask yourself what you need from the lighting. Task lighting enables you to see what you are doing. Common examples include a reading or desk light and down lighters under kitchen cupboards or an extractor hood.  Decorative lighting can also take several forms such as up-lighters or spotlights on pictures or architectural features. Light coming from different sources can produce a pleasant visual effect, and with light focused towards where it is needed, you can reduce the wattage of “general” lighting, reduce its use or do away with it altogether.

  • Light fittings and shades

Light fittings with multiple bulbs often work against energy efficiency. Those with moveable spot lights can give you the flexibility to change the room layout and still achieve good lighting effects. Avoid thick, heavy shades that limit light output or choose ones with wide openings to the room. If you are concerned about the appearance of energy saving light bulbs, opt for large, translucent shades or a different shape of light bulb.

  • Buying low-energy bulbs

Most hardware shops sell compact fluorescent bulbs, however the choice of LED bulbs is still relatively limited.  If you are looking to replace a range of bulbs with LED then use a specialist online lighting supplier such as or CP Lighting.

  • Best practice guidance               

Energy Saving Trust publication “CE61: Energy efficient lighting - guidance for installers and specifiers” provides further technical information.

This fact sheet explains how to:

  • Reduce the energy consumption of your lighting
  • Design new lighting to use less energy
  • The best time to consider the energy efficiency of your lighting is RIGHT NOW: changing from old to new bulbs will cut your lighting costs and emissions by up to 90%!
  • Some other opportunities are when you are:
  • Replacing a lighting fitting
  • Re-wiring your property
  • Refurbishing individual rooms or a whole house

Taking action NOW will save you money for years to come.