LED Downlights: Choosing the right one
Not all LED Downlights are created equal.
It is true that LED lighting technology can provide significant energy savings in both domestic and commercial applications.
While the benefits of LED lighting are generally understood, what many consumers don't realize is that LED downlights vary considerably in quality. There are good quality LED downlights and poor quality ones.
The majority of LED lighting manufacturers all promise unparalleled performance in terms of lifespan, quantity of light output and the quality of the light produced, but they can’t all be right when the price differs so much, can they? As with most products price is generally a good indicator of quality.
So what makes an LED downlight poor quality?
Firstly, a common misconception is that LED's run cool. This is definitely not true. Although they do not get as hot as incandescent or halogen bulbs they still produce a significant amount of heat which must be drawn away from the LED otherwise the LED will lose efficiency or fail prematurely. LED's actually convert around 20% of the input energy in to wavelengths which are visible to the human eye with the balance dissipated as heat. (Incandescent lamps only convert 5% of the energy in to light).
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Good quality LED downlights therefore must incorporate a highly effective heat dissipation system. This system is most often in the form of a Heat Sink on the back of the downlight. The heat sink absorbs the heat produced by the LED chip set and then dissipates this heat into the surrounding environment by convection and radiation. Be wary of LED downlights which state they can be covered with insulation!
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If the heat sink doesn’t fulfil its job correctly, the LED will overheat and most likely burn out. So a badly designed heat sink will be detrimental to the lifespan of the LED downlight.
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Secondly, LED's produce visible light by converting their blue light in to other visible wavelengths. This is accomplished by a coating of phosphors on the LED chip. The phosphors are energized by the high energy wavelength of the blue light and produce other visible wavelengths. Poorly manufactured and or applied phosphor coatings can mean a higher than acceptable amount of blue light is being emitted in to your living space and this can cause irreversible eye damage.
Lighting Terms Lumens (lm) |
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Lumen is the unit for measuring the amount of visible light produced by a light source. The higher the lumens, the brighter the light.
Lumens per watt (lm/W)
This truly shows the efficiency of the LED product. For example a 650lm product consuming 10 watts of electricity = 65 lumens per watt. Lumens per watt vary from product to product depending on the LED chip used, how hard the product is being run, and the construction of the fitting and how effective the heat sink is at removing the heat.
Beam angle
The beam angle is something you need to pay attention to when choosing the right LED lighting for the space. This is as important as the Lumens. Beam angle indicates the spread of light from the light source. A narrow beam gives a concentrated light which is better for accent lighting. A wide beam gives a more general, softer light.
Lumens per watt (lm/W)
This truly shows the efficiency of the LED product. For example a 650lm product consuming 10 watts of electricity = 65 lumens per watt. Lumens per watt vary from product to product depending on the LED chip used, how hard the product is being run, and the construction of the fitting and how effective the heat sink is at removing the heat.
Beam angle
The beam angle is something you need to pay attention to when choosing the right LED lighting for the space. This is as important as the Lumens. Beam angle indicates the spread of light from the light source. A narrow beam gives a concentrated light which is better for accent lighting. A wide beam gives a more general, softer light.
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Warm white and cool white (Kelvin,K)
The colour temperature of a product is a linear scale of measuring the colour of light. Measured in degrees, Kelvin, warm light is measured in lower numbers and cool white in higher numbers. It is down to personal preference whether you choose warm white or cool white. Cool white is ideal for task-orientated areas like kitchens and laundries and areas that have a warmer climate as the lighting will help to make the rooms feel cooler. Warm white helps to create a more intimate atmosphere suited to bedrooms and living rooms and these colour temperatures create a more relaxing and comfortable environment. A tip is to stick to just one colour throughout an open plan living area, otherwise the mixing of colours will be distracting to the eye. |
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Colour Rendering
Colour Rendering is the ability for a light source to give a true reflection of the colours of the object it is illuminating. Essentially the higher the colour-rendering index the closer to daylight the bulb is. The Colour temperature of the LED lamp is not relevant. (daylight portrays objects perfectly – it has a CRI of 100%).
If the lights are used as your general lighting then you want to select LED downlights with a CRI of 80+. The higher the CRI of the bulb the more expensive it should be to buy. If you are into painting for example, you will want to ensure the bulb has a CRI of 90+ to ensure you are getting a more true view of what you are painting.
Colour Rendering is the ability for a light source to give a true reflection of the colours of the object it is illuminating. Essentially the higher the colour-rendering index the closer to daylight the bulb is. The Colour temperature of the LED lamp is not relevant. (daylight portrays objects perfectly – it has a CRI of 100%).
If the lights are used as your general lighting then you want to select LED downlights with a CRI of 80+. The higher the CRI of the bulb the more expensive it should be to buy. If you are into painting for example, you will want to ensure the bulb has a CRI of 90+ to ensure you are getting a more true view of what you are painting.
