Going Green and LED fairytales in lighting
A must read for all people involved in lighting that are considering LED's as a light source.
What does it mean to 'go green'? - 'reducing carbon footprint' 'minimizing impact on the environment' are terms that spring to mind - yet so many people in the lighting industry seem to believe this means getting rid of the more tried and trusted lighting sources in favour of the newer 'more efficient' light sources - and surely that does not just mean switching to LEDs or CFL's wherever possible - surely it means getting the most usable light for every watt of power confused? (Also known as lumens per watt or efficacy)
More efficient - this is important - lighting levels need to be maintained to meet with legislation.
Legislation - although sometimes outdate, is mostly there to protect the consumer, poor light levels may have bad repercussions.
Very often, older 'seemingly less efficient' lighting systems are replaced with newer - seemingly more efficient systems - and very often you will find people running around saying we reduced the electrical bill by 30%. Well that is fine. provided the correct lighting levels were maintained or achieved, and not only the levels but also the quality of the light needs to be correct.
I reckon every person who gets to look at LEDs has heard the following claims:
1. You can replace any light source with LED sources - and get the same quality and quantity of light.
2. LEDs last 50 000 to 100 000 hours.
3. LEDs are the answer to all the lighting problems.
Bold claims, sweeping claims - but are they true?
I wish there was a simple answer but there isn't, and that makes decision making for the lighting specifier difficult.
The thing is that any person who has the means to get themselves to a lighting trade fair in the east, can then select from thousands - and I mean literally thousands of LED lighting 'manufacturer/suppliers'. They can then put together a sample range come back home to SA and then proclaim themselves LED/lighting experts and go around selling LED lighting products.
So now you have a plethora of 'LED' experts running amok selling LEDs based on the claims made by the manufacturers in the east. Clients then buy these products in good faith only to be disappointed when light quality is below expectation or the LEDs begin to fail prematurely.
Buyers of lighting need to beware of LED products, and need to either do their own research into the products or select reputable lighting people to do the research for them before just going out on a limb and buying - because it is the fashionable, energy saving thing to do.
Here are some simple facts:
LED lighting comprises of many parts;
1. You have the LED chip - that is a little bit that actually produces the light.
2. This is placed in some sort of housing that has electrical terminals, now you have a device known as an emitter.
3. This housing is usually placed onto a printed circuit board (PCB) to enable easy routing of electricity to the LED.
4. A power supply - suitable for the LED source is then required to power the LED up.
5. High power LEDs (half a watt and upward) need additional cooling devices added to the PCB to keep them operating within a temperature range.
And all of these items mentioned above need to function in a specific way - interrelated to each other.
Now that we are armed with this information we must not forget one salient fact - not all LED chips, or housings or PCB`s or power supplies are created equal. Just like in everything else you get good, and you get bad.
This is your simple checklist as a lighting specifier/user.
How much light does the LED module you intend buying produce in terms of what it is meant to replace. For example - you want to replace an MR 16 low voltage lamp. A good halogen lamp will have a source that produces 600 lumens in 35W format or 1100 lumens in 50W format. Halogen is always around the 3000K colour temperature.
A good LED source will not produce more than 85 lumens per watt (in 300K format) under operating conditions (also known as 'hot lumens') do not get confused with claims made in data sheets - these are under laboratory conditions and at 25 degrees C.
Most LED retrofits for the MR 16 lamp have three LEDs in them - so all you get is 255 lumens. You can stand on your head but you will not get more than 255 lumens or therabouts. People may say - yes but the LED's optics are more efficient and that may be so but this will not make up the 350 or 850 lumen deficit.
So- if you want to keep your LED source below 11W (by today's outputs), live with the face that you will need more units to get the same light levels you were used to. In essence you would need 2-3 such LED retrofits to do what one 50W halogen MR 16 was doing. YOU WOULD STILL BE SAVING MORE THAN 40% OF YOUR POWER THOUGH.
So - yes LEDs are a viable alternative to halogen, now what about other common light sources like metal halide, linear flourescent, high pressure sodium or even the rare but available induction (or not so available plasma lamps).
The best way to illustrate exactly where LEDs are positioned compared to other sources is to have a good old fashioned shoot out! Bear in mind this shoot out is based on today's figures - this will change as LEDs get better and cheaper.