Lighting technology has advanced a long way since the tungsten filament light bulb was invented in 1910 yet you can still find essentially the same design of light bulb in many houses today. In more recent years, however, compact fluorescent lamps (CFL), usually called low-energy light bulbs, came available. CFLs consume at most only a fifth of the energy of a filament bulb and last at least eight times longer than an equivalent filament lamp. CFLs are now being superceded by LED (light-emitting diode) bulbs, which are more efficient still and last some twenty five times longer than a filament lamp. It is time for all of us to reconsider the lighting arrangements in our homes. Indeed, the government agreed with major shops that they would no longer stock incandescent bulbs of any wattage after 2011.
It is sometimes argued that because energy efficient bulbs are cooler (because less energy is wasted as heat) you will need to heat your home more. In fact, although 90-95% of the electricity is no longer ‘wasted’ in heating your home, the amount is trivial; in warm weather you won’t miss this heat anyway. Click here to dispel some other myths about energy efficient bulbs and to obtain advice about which bulbs to buy.
UK households cause the emission of 9 million tonnes of carbon dioxide every year just from lighting. If a low-energy bulb uses only a fifth of the energy of the filament bulb it replaces then obviously the associated carbon dioxide emissions are cut by a factor of five. Changing light bulbs is something that almost anyone can do immediately and it is easy to do.
Switching to LED bulbs need not cost very much, the typical price is about £2 - £5, and it saves money on your electricity bills straight away. When you’re shopping for energy saving light bulbs, look for the "Energy Saving Recommended" logo. It’s the quick and easy way to spot the most energy efficient products on the market. Some organisations give these bulbs away free: look out for advertisements in newspapers and magazines and stalls at fairs and markets.
1. Switch to LED light bulbs
Changing over to LED light bulbs is one of the easiest and most effective ways to reduce your greenhouse gas emissions. It is so effective that it’s worth doing straightaway, not waiting until your existing bulbs need replacing.
Traditional filament bulbs can easily be replaced with LED bulbs (either CFLs or LEDs) which are up to ten times more efficient than filament bulbs. LEDs are generally the same size and have the same bayonet or screw fittings as the filament bulbs they replace and some are even designed to replicate the filament design of traditional bulbs. It is now possible to use a dimmer switch with some LED bulbs.
When buying a LED light bulb, consider the brightness, in lumens, that is now almost always written on the packaging. The bulbs are, like the old filament ones, labeled with their power requirement in watts however to make a comparison you should look at the lumen output (the total amount of light output) rather than the wattage. Generally an old 60W incandescent bulb produces about 860 lumens; so for a direct replacement you would need an LED bulb with this output (typically 8-10 Watts). Bear in mind also that bulbs tend to get dimmer as they age, so newer bulbs usually look brighter anyway.
Halogen bulbs, such as those found in ceiling downlighters, are more efficient than traditional filament bulbs but are still nowhere near as energy efficient as LED bulbs (see below). If you have ceiling downlighters (mains-voltage GU10 or low-voltage MR16), consider replacing standard halogen bulbs with LED bulbs. Good quality LED bulbs are available from around £2 and will pay for themselves in less than six months in energy savings.
Another aspect to consider is the ‘colour temperature’ – this is a measure of how “warm” or “cool” the light is. First-generation bulbs had a cool bluish tint, however the latest bulbs replicate the feel of incandescent bulbs very well. If this is what you want then look for a colour temperature of 2700K (this should be displayed on the packet) – anything higher will tend towards a cooler tint, whereas lower moves towards a warm orange tint.
As an example of the savings you can make from switching bulbs, if a 100-watt filament bulb is used on average for 2 hours a day in summer and 4 hours a day in winter it consumes 110 kWh of electricity in a year. Replacing this one bulb with a low-energy bulb will save 88 kWh of electricity and around 35 kg of carbon dioxide. When this figure is multiplied by the number of bulbs in the home, and allowing for a range of different wattages and hours of use, you can see how the annual savings could approach several hundred kg of carbon dioxide.
In the above example, replacing a single 100-watt bulb with an equivalent low-energy bulb will save around £14 per year on your electricity bills, quickly repaying the slightly higher cost of the bulb. The total saving in your home each year will depend on the number, wattage and usage of all the bulbs in your home.
2. Turn off lights which aren’t needed
The easiest way to save energy used for lighting is to ensure that lights are not left on in unoccupied rooms. Try to get into the habit of switching off lights every time you leave a room. If you can also adjust the lighting to suit what you’re doing, then more energy is saved. For example, it is not necessary to have strong lighting for watching television and if you are reading then a single smaller reading lamp may be enough.
As an example, if you manage to save the use of one 100W bulb for an hour a day that will amount to a saving of almost 15 kg of carbon dioxide in a year (but at least five times less for an equivalent energy efficient bulb). This may not sound much but if every household in the UK did that it would save the emission of over 300 million kg of carbon dioxide a year, about 5% of the total emissions for domestic lighting!
You will save a little money from switching off one 100W bulb for an hour a day, about £5 per year (and around £1.10 for an equivalent low-energy bulb).
3. External lighting and sensors
Some people like to use spotlights and other lights to illuminate the outside of their homes at night. This may be to make the house appear more welcoming to visitors and returning occupants or to create a sense of security because the lights are expected to deter unwelcome intruders. In either case, most of the time this lighting is unnecessary and lower-energy solutions can be found.
It is simple to replace existing filament bulbs with same-size low-energy light bulbs in exterior fittings, or better still replace them with new LED units. Further, exterior spotlights are usually more powerful than interior lights, and so they use more energy, and if they are left on all night, even after the sun has risen but before the occupants are up, then the potential for reducing energy consumption is even greater. Two obvious solutions are to control the lights with a light sensitive switch kit, that switches on at dusk and off at dawn, and/or to use a passive infrared (PIR) sensor, that senses when a warm body moves within range, to switch security lights on for a pre-determined period after which they turn off again. Remember that if you carry out any electrical re-wiring it should be checked by a competent electrician.
Halogen spotlights are energy intensive, but some other exterior lights, such as those used to mark a path, use light emitting diode (LED) technology. These run at low voltage and low wattage, and therefore use very little energy. Using a PIR sensor on security lights, possibly with a light sensitive switch as well, should ensure that they are off most of the time without jeopardising home security.
Exterior lights need special fittings and waterproof housings which add to the price. Halogen spotlights are a lot cheaper than LED lights, although the price of the latter has come down considerably in recent years. Timers can be bought for less than £10. PIR sensors start around £20. It is even possible to use solar-powered LED lights for marking paths (about £35 each) or as security lights (about £25 each).#
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The information on this page is provided in good faith and reflects our understanding of the underlying science and technology at the time of writing, but we cannot guarantee that it is wholly accurate. All figures for costs, savings and other matters are estimates: the actual figures will depend on your particular circumstances and may differ (perhaps significantly) from those shown. Although we have included links to various organisations, we are not recommending these organisations: it is your responsibility to check that they are suitable for your needs. Nonetheless, if you experience difficulties with any of the links or organisations, or believe that any of the information presented here is inaccurate, please let us know and we will update this page if we consider it necessary.