LED Lighting Characteristics Explained
LED Lighting is the next generation of consumer lighting products becoming available across the world. The nature of light emitting diode’s allows them to be incorporated into almost limitless designs due of their high efficiency and versatile sizes. Most commonly in Australia, new retrofit designs of existing fixtures and lamps are now available with LEDs incorporated. This article endeavors to explain some characteristics of LED lighting which need to be addressed for a proper design.
Limitless Designs with LED Technology
Light emitting diodes are exactly what they say they are. A small diode which emits light when electricity is passed through the circuit. LEDs themselves are available in wide range of colours, sizes, power ratings and light qualities, however recent developments in LED technologies now allow the use of surface mounted diodes (SMD) to be easily incorporated into retrofit designs. What we mean by retrofit designs is the ability create similar lighting effects of traditional lighting such as incandescent, halogen and compact fluorescent lights.
Efficiency of LED Lighting
The traditional way of measuring a lights ‘efficiency’ is by referring to the lumen output per watt. LED lights have aspects which affect the efficacy of the light. As such two major lighting characteristics that can affect a LED lights efficacy is the colour temperature and the colour rendering index. White LED lights are available in colour temperatures ranging from around 2000 kelvin (K) all the way up to 10000K. On this scale using the same LED chip it is apparent that the higher the colour temperature the better light output, or lumen per watt output is achieved. In simple terms, a cooler white colour is brighter than a warm white for the same power consumed.
Light Quality of LED Lighting
The quality of light produced by a luminaire is often expressed by using the colour rendering or rendition index (CRI) based on a scale of 1 to 100. Natural sunlight covers the widest range of light wavelengths and due to this, the benchmark is natural sunlight which achieves 100 CRI. This means that the colours of objects you see are the ‘natural’ reflected colours. The record for a phosphor blend in LED has been 98 CRI. Ideally you should choose a LED with a reasonable CRI (75+) if you don’t want to look like a green goblin. Often colour and light quality are compromised when using super high efficacy LEDs.
Colours of LED Lighting
LED lights are now available in a wide range of colours but choosing the right LED light can still be tricky. In an ideal world if you want a light with a warm white colour you would choose one that says “warm white” in the specs, but buyer beware, warm white to some manufacturers is actually yellow, and similarly yellow often turns out to be amber or even orange in some cases. We recommend you always refer to the colour temperature of the LED light in conjunction with the CRI. The warm incandescent colour that most of us have grown to love is usually emitting 2700K to 3000K. A netural white colour is generally emitting at 4000K to 4200K and cool whites from 5000K to 7000K. Whilst we long to have consistent colour in our lighting, cheaper LED lighting manufacturers often cannot supply LEDs with a consistent a colour temperature due to their manufacturing process and quality control. For example, a warm white LED light may be supplied with a colour temperature range of 2700K to 3500K, what this means is that the colour of one light may differ slightly to the next depending on the manufacturers quality control.
Electrical Components in LED Lighting
The lifespan of a LED light is always going to be dependent on the power supply used to drive the LED chip. Poor electronic components in cheaper LED lights can often lead to unexpected or ‘catastrophic’ failures, flickering, strobing, poor brightness and so on…
Remember that a LED can only continue to deliver light if the electronics driving the LED continue working. The simple way to overcome this is to purchase from a reputable company or manufacturer that also offers a generous warranty.
Lifespan of LED Lighting
The lifespan of a LED is usually quite long and often ranges from 25,000 hours all the way up to 100,000 hours at which the LED lamp will reach a lumen output totaling 70% of it’s original rated lumen output. However to achieve this long life the LED light needs to have quality electronic components that can also last the same lifespan, have sufficient thermal control / heat management and also be powered correctly. Without these key ingredients being incorporated, your LED light won’t last, so considering the current cost of LED lighting it is even more important to purchase LED lights from manufacturers with experience.
Thermal Management and Heat Control in LED Lighting
One of the most important aspects of LED lighting is the luminaire’s ability to dissipate heat effectively. All LED light’s lifespan is affected by the temperature at which they operate at and the ambient temperature. Designs of quality LED lighting often incorporate heat sinks into the fixture or lamp to allow the heat to dissipate. Smart manufacturers use built-in thermal control in their lamp or power supply (transformer/LED driver) which can reduce the power supplied to the LED thus lowering the output to reduce the heat produced and some even can control the speed of a built-in fan to force the heat out of the fixture or lamp depending on the temperature limitations set.
Spread of Light in LED Lighting
Light emitting diodes are quite small and directional in nature, luckily because of this the ability to spread the light can be controlled easily with the use of reflectors and different lenses. For example, a surface mounted diode with no lens or reflector would emit light in a 150º beam or spread. With the use of a lens incorporating a prismatic structure the light emitted can be directed into a focused beam. The use of reflectors can also achieve a similar result but without compromising the LEDs output by transferring light through a solid medium. Reflectors are by far a smarter way to direct light, but can often increase glare because of the lack of frosted perspex.