LEDs have – and still are – revolutionising the lighting marketplace, yet they are very different light sources compared with their traditional and conventional counterparts. For this reason, Thorn Lighting has compiled a very useful guide to help customers understand the LED lighting product they are purchasing or installing:
With lighting accounting for around half of electricity usage, it provides a major opportunity in a company’s quest to save energy. The development of LED has given us a low energy, long life light source, but it also presents great design challenges. In these early days of this technology, many products have been beset with short life and quality issues such as colour and output that have often disappointed their users. Generally this is caused by component or product design issues rather than the quality of the LEDs themselves.
In the light of this, it would help to provide a concise guide about the crucial aspects to look for. Here it is:
Top tips for buying LED
1) Lumen Output (lm/W) - Lumens are generally stated out of the luminaire, not the LED itself (as was the case with conventional lamps). For example, when replacing a 2,000 lumen lamp, compact fluorescent luminaire (CFL), look for an LED luminaire of circa 1,400 lumens. This should be clearly stated as ‘Luminaire Lumens’. Too many lumens may produce glare and wasted energy, while the wrong distribution will put the light where you don’t want it and not enough where you do.
2) Luminaire Efficiency / Efficacy (Luminaire Lumens per Watt) - This is a measure of how much light you receive from the complete fitting for each watt of electricity consumed. Beware of statements of ‘Lamp Efficacy’, as we want to know how efficient the luminaire is, not the lamp – note that the Lamp Efficacy will always be higher.
3) Colour Temperature – This is how warm or cold the luminaire looks when switched on. LED is more efficient at colder colour temperatures (4200K +) but this is an undesirable way of increasing efficacy as it produces a cold blue colour that most people find uncomfortable. The normal recommended choice is to choose 4000K for office, retail and applications that require higher levels of illumination (circa 300 lux +) and the warmer 2700k to 3000K for areas requiring lower levels of lighting, such as residential, restaurants and areas of relaxation.
4) Colour Rendering (CRI / Ra) - The value ranges from zero (you won’t be unable to distinguish colour) to 100 (excellent ability to distinguish colours). Legally in the workplace, with certain restrictions, you must provide a colour rendering >80. Note that increased colour rendering often means a decrease in efficiency. Ra=80 works for most applications, but if possible, sample a luminaire beforehand to be sure that it will suit the space and items you wish to light.
5) Lifetime - Look out for the mean average rate life or useful life figure. These should be stated as L70 50,000hrs, or L70B50 50,000hrs. This means that after fifty thousand hours, the LEDs within the luminaire will on average give out 70% of the light output that they did when the luminaire was first turned on. Research demonstrates that most people cannot tell a 30% drop in output, so it’s a sensible figure. Chose a lifetime relevant to the task, for example 50,000 hours in a hotel corridor that is always on equals six years, but in an unused store room it may be 25 years or more.
6) Glare - In some applications like outdoors and workplaces there is a legal requirement to control glare. In other cases it’s a matter of comfort. Some luminaires are labelled to indicate good glare control, such as a listing of UGR<19. Generally these are suited to office use, but as glare depends on the overall building design it’s always wise to ask.
7) Data - Lighting is all about high performance, so check the manufacturer’s website. Data to look out for are photometry files, CE conformity, installation leaflets and power factor. A well designed product will have more available data than just watts and lumens.
8) Warranty and Support - Look for at least a five-year warranty and then read the small print to determine what the warranty really offers. It is advisable to choose a product where the manufacturer has a help desk and support team.
9) Reputation - LED has allowed many new suppliers to come to the market. Remember that you’re buying a product that lasts many years, so you should look for a company that has been around long enough to gain a reliable reputation. It’s never been a better time to go with a name you know and trust. Likewise look for branded LED boards and drivers inside the product as this will give confidence that the components are supplied by recognised component manufacturers.
All Thorn products are tested to the highest standards and certified by the BSI, before they are introduced to market, so you can rest assured that you are purchasing a high quality performance product with support you can trust. Should you require any further information on LED lighting please contact us on tel: 0844 855 4810, or go to: www.thornlighting.co.uk