Changing a light bulb is one of the easiest yet most effective ways of reducing energy consumption and cutting carbon emissions. Simply replacing an incandescent bulb with an energy saving alternative can cut electricity use by up to 80%. The Energy Saving Trust believes that lighting accounts for 8% of household electricity costs in the UK which means there is great potential for substantial energy and money savings.
The seemingly straightforward task of choosing a light bulb has however become a bit of a mine field in recent years. The plethora of light bulbs and lighting technology on the market and the rapid pace of development in the industry is both cause for consumer celebration and caution. Greater range of choice gives consumers unprecedented freedom but also means it is more important than ever to choose the right light bulb for the right application. Comparing lumens per watt values is an easy way to identify the most “light” efficient lamp in terms of brightness. But to work out which lamp type is best for a specific application in terms of energy efficiency the following things need to be considered: wattage, lamp life, daily use, lamp cost and lighting output required. The best way to do this is with an energy saving calculator. By entering specific values you can compare your current light bulbs with those you are considering replacing them with and make an informed lighting decision based on an energy saving forecast.
So what energy savings options are there? Everyone is talking about Light Emitting Diodes (LED) at the moment and rightly so given their dramatic advances recently in lumen efficacy and lamp life. Depending on the application, compact fluorescents (CFL) and halogen energy savers are also an effective way to save energy. In most cases a retrofit replacement lamp can be found and energy saving bulbs are available in all the normal cap types including bayonet, Edison screw, GU10 and many more.
LED is regarded as the most effective form of low energy lighting available and many in the industry expect it to have a market share of around 50-60% by 2020. Unlike some other forms of lighting, in particular incandescent, LEDs are efficient because most of their electrical energy goes towards the light-production process. An incandescent bulb, for example, requires its filament to glow white-hot before producing visible light, thus heat is generated as a wasteful by-product which uses around 80% of electrical power. In comparison, less than 10% of LED electrical consumption is emitted in the form of heat.
LEDs produce light by the process of Electroluminescence. This is the phenomenon where by light is emitted from a material when an electrical current is passed through it. An LED chip is made from a material doped with ‘impurities’ to create a p-n junction between two types of semiconductors and electron holes. Electrons can only flow one way across the junction and as they do they fill electron holes causing their energy level drops and the release of photons (light).
The high price of LED has been a significant deterrent for many in recent years. However, as the cost of semi-conductor material falls and companies vie for consumers so LED is becoming a more cost-effective option. In conjunction, improved heat sink technology and reliability is giving customers the confidence to view LED as a long term investment. These days a typical lamp life of 20,000-50,000 is the norm and not an unrealistic manufacturer claim. Some lamps, such as the new Philips Xtreme tubes even last up to a staggering 79,000 hours. It is worth also noting that not all LED are dimmable so check before purchasing if this is something you require.
For businesses where lights are in continuous use all year round LED is an obvious lighting choice. Long life ensures maintenance costs are low and the initial cost of replacing lamps is offset by substantial energy savings during the lifetime of the bulb. A high profile example of this is John Lewis’ decision in November 2012 to turn its back on ceramic metal halide lamps and install LEDs throughout its new Ipswich branch.
Whether LEDs are right for domestic use as an energy saving option comes down to the application and the situation. The question to ask is: will I recoup the cost of the lamp and more through reduced electricity use and long lamp life? If yes, then LED is the way to go, if not, there are other energy saving alternatives available.
CFLs (Compact Fluorescent) only use 20-25% of electricity used by incandescents, making them a popular energy efficient choice for homes and businesses. The fluorescent tubing of the lamps can be bent and folded into a variety of shapes. Double turn, triple turn, quadruple turn and spiral shaped bulbs are a standard form but the advent of bulbs such as the Plumen, the world’s first designer energy saving light bulb which derives its name from the feathers of a bird and the unit of light, suggests new shapes will continue to appear. For most lamps electronic ballast is contained within the base of the lamp although separate operating ballast may be needed for different voltage operations.
CFLs typically cost as little as £2.00 and they have a lamp life of 6,000-20,000 hours. This makes them ideal for applications used for a few hours daily and especially for those looking for instant energy savings at low initial outlay. In the past concerns have been raised regarding slow warm up times and flickering but if a good quality CFL is brought today this should not be an issue.
Light quality and colour can dramatically change the appearance of a room so it is important to get this right. You wouldn’t, for example, want bright white lighting in a bedroom, instead a soft warm white ambiance would be more suitable. When choosing a light bulb you first need to decide which colour temperature you require. Colour temperature is a measure of how warm or cool a colour appears. It is measured in Kelvin; the standard measurement for lighting output in addition to lumen output. Colour temperature is derived from the colour of light produced when carbon is heated. The Kelvin Scale ranges from extra warm white at 2,700k giving a warm yellow glow, to white at 3,500k, cool white at 4,000k and daylight colour at 6,500k which produces a white blue colour. LED, CFL and halogen energy savers are all available in a range of colour. Complaints have been made in the past about LED giving off a cool blue light but with the improvement in technology, as long as you buy a good quality LED this should not be a problem. It is then important to look at the colour rendering index (CRI) which shows to what extent the light will make an object appear its true colour. An incandescent bulb is rated at 100% because its light contains a full spectrum of colour. CFLs do not contain the full colour spectrum but a good quality triphosphor fluorescent rated between 80-90% will be sufficient for everyday use. Higher rated CFLs can be obtained but are usually only used by designers or artists and are less efficient. It is advisable not to buy a light bulb which scores below 80% on the CRI scale. Energy saving light bulbs have received a bad press at times because of the light they produce, but this has tended to be because many poor grade CFLs either brought from supermarkets or given out for free by energy companies have come onto the market.
Another energy saving option is the halogen energy saver. These lamps only offer around a 30% energy saving over incandescents and typically last 2,000-5,000 hours but they do have some advantages over LED and CFLs which are worth considering. In some cases truly retrofit LED can be hard to find and difficulties with the fitting and size of the lamp can occur. The nature of a CFL means its appearance differs from that of an incandescent. Halogen energy savers are however available in a range of shapes including spot bulbs, GLS, candle, aluminium reflector and golf ball making them an easy retrofit replacement for many traditional incandescents and an option worth thinking about particularly if you require decorative on show lighting. For those wishing to retain the traditional shape of their lighting long term, a G9 halogen adaptor is a great way to do so. A G9 halogen capsule is fitted in to the adaptor base (available as SBC, BC, SES, ES) which is in turn screwed into a decorative cover. Once the halogen capsule has expired, the bulb can be unscrewed and only the capsule needs replacing – meaning your decorative lighting remains the same. Another advantage of halogen energy savers is that unlike some LED and CFL they are fully dimmable. Furthermore halogens and CFLs emit light evenly whereas LEDs emit light directionally so make sure to check the beam angle before purchasing to ensure you get the right light output.
Technology has evolved rapidly in the lighting industry over recent years and shows no signs of abating. With the continued legislation against inefficient light bulbs and consumers looking to make savings, energy efficient bulbs will be the way forward. LED, CFL and halogen energy savers are the main options and each type has a role to play depending on the situation and lighting requirements. Always make sure to buy good quality lighting from a trustworthy company and avoid those out to make a quick profit, especially where LED is concerned. Finally, remember when choosing light bulbs an energy saving calculator is the best way to compare technologies.
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